yosemite to flood??

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Messages 1 - 202 of total 202 in this topic
Matt's

climber
Topic Author's Original Post - Jan 4, 2017 - 06:32pm PT
Looks like they are predicting near-record levels on the merced river this sunday:

http://water.weather.gov/ahps2/hydrograph.php?wfo=hnx&gage=pohc1


EdBannister

Mountain climber
13,000 feet
Jan 4, 2017 - 06:40pm PT
http://www.cnrfc.noaa.gov/obsRiver.php?id=POHC1

here is the link for actual... updated hourly... and it is rising...

it has been over 19 feet only 3 times since 1938, we will see if it is so warm that the drainage basin gets rain instead of snow.... lets hope for more snow than rain. The models can be correct about precipitation and wildly wrong about runoff if it gets cold enough to snow instead of rain... i hope for less than 19 feet, maybe only 15 feet, that would be great for the Valley...

At least we do not have to wait 400 years to see if the models were correct. we will be able to say yes or no, in 4 days.
Clint Cummins

Trad climber
SF Bay area, CA
Jan 4, 2017 - 06:57pm PT
Wow, looks like a repeat of the previous record, 20 years ago.
Impacts - E19 Information
6.5 Feet River is closed to rafters and floatation.
9.0 Feet Chapel Meadow (south side of river) and Cooks Meadow (north side of river) begins to experience overflow.
9.5 Feet Portion of Lower Pines Campground becomes flooded. Limited site-specific evacuations begin at Housekeeping Camp located along the south-facing bank of the Merced River. (Upstream from Sentinel Bridge and downstream from Stoneman Bridge)
10.0 Feet Western portion of North Pines Campground, located at the east end of Yosemite Valley between the confluence of the Merced River and Tenaya Creek, begins to flood. Water rises to the base of the swinging bridge downstream from Chapel Meadow.
10.5 Feet Water tops the swinging bridge downstream from Chapel Meadow. Overflow from Woski Pond floods access road (Northside Drive) leading out of the west entrance of the park.
11.5 Feet Sewage pumping relay station at North Pines Campground becomes flooded.
12.5 Feet Northside Drive and Southside Drive, which are the main roads in Yosemite Valley, become flooded and are closed to traffic.
23.45 Feet Flood of record (01/02/1997). $178 Million damage to Yosemite Valley.
[Click to View YouTube Video]
http://www.supertopo.com/climbers-forum/1097492/Yosemite-Flood-97
crankster

Trad climber
No. Tahoe
Jan 4, 2017 - 06:58pm PT
Yikes.

The river that flows through fabled Yosemite Valley is expected to overflow its banks during this weekend’s storms, rising even higher than it did during the devastating flood of 1997.
Forecasters with the National Oceanic and Atmospheric Administration predicted that the Merced River would surge to a level of 23.7 feet, about a half a foot higher than it did 20 years ago when the river flooded a valley hotel and other facilities, causing an estimated $176 million damage.
Srbphoto

climber
Kennewick wa
Jan 4, 2017 - 07:43pm PT
saw Mammoth has a base of 170" on top and 80" at the lodge. With 30" to 50" of new. They already received 135" at the lodge this year.
EdBannister

Mountain climber
13,000 feet
Jan 4, 2017 - 08:01pm PT
and incredibly, there is no threat listed for Monday... warmer rain... i don't get it
WBraun

climber
Jan 4, 2017 - 08:09pm PT
The 97 flood was because it rained like hell above 10,000 feet with a huge snow pack already laid down.

We fought like hell to save the pumps. It was brutal in the icy river pushing logs aside.

I thought I was going to die of hyperthermia.

Lober and Jeff Sullivan did last way longer than I did in that freezing water.

We had to use jumars onto ropes tied to trees to get back against the current.

It was overwhelming.

Then all was lost, because pumps failed and got destroyed .......


Matt's

climber
Topic Author's Reply - Jan 4, 2017 - 08:11pm PT
werner-- what do you mean by pumps? Sewer pumps?
Matt's

climber
Topic Author's Reply - Jan 4, 2017 - 08:12pm PT
Also-- I have a friend who is considering flying in in late january. If flood waters do reach 23ft, will the valley likely be closed for a while?

thanks,
matt
WBraun

climber
Jan 4, 2017 - 08:14pm PT
Yeah Matt, the sewer pumps .....
Matt's

climber
Topic Author's Reply - Jan 4, 2017 - 08:17pm PT
Kingtut-- I was referring to whether the roads would be closed.
EdBannister

Mountain climber
13,000 feet
Jan 4, 2017 - 08:25pm PT
the ggeeekboy model only forecasters apparently do not have a hallowed "Model" for warm rain on snow, the model shows no threat after sunday,,, nuts. lets just hope it snows hard and it stays well below the prediction.. after all the NOAH office of 30 day forecast used to be 60% inaccurate, you could flip their forecast and be better than they were.
WBraun

climber
Jan 4, 2017 - 08:27pm PT
During the 97 floods the park was closed because the sewage pumps were destroyed and the sewage pipes going to the treatment plant in el portal were destroyed.

The whole infrastructure to was destroyed ......
EdBannister

Mountain climber
13,000 feet
Jan 4, 2017 - 09:52pm PT
it was after satellites and doppler dingus...

let's just watch what happens,
and you can tell me i told you so if it gets to 23 feet on sunday,
and i will tell you the models suck if it never tops 19 feet.

personal prediction, not over 17 feet, what is your number Dingus?


and what if the real high comes on Monday, where my concern is,
and the model boys raise no concern...

then we can feel bad about the damage together.
Bluelens

Social climber
Pasadena, CA
Jan 4, 2017 - 10:10pm PT
https://twitter.com/yosemitenps/status/816776069877362688
Gunkie

Trad climber
Valles Marineris
Jan 5, 2017 - 10:13am PT
So what needs trundling?
EdBannister

Mountain climber
13,000 feet
Jan 5, 2017 - 10:34am PT
Ok that is funny

But the prospect of 23 feet is not...
Hope for snow
matty

Trad climber
under the sea
Jan 5, 2017 - 10:55am PT
Prediction lowered to 15.5ft per link in opening post.
Mr_T

Trad climber
Northern California
Jan 5, 2017 - 12:13pm PT
So what needs trundling?

Trundling was the order of the day in 97. A big block near the top of the Nose was cut loose then.
nature

climber
Boulder, CO
Jan 5, 2017 - 12:53pm PT
seems like an appropriate thread for this:

Clint Cummins

Trad climber
SF Bay area, CA
Jan 5, 2017 - 08:12pm PT
Current forecast is 15.9 feet at 4pm Sunday.
http://water.weather.gov/ahps2/hydrograph.php?wfo=hnx&gage=pohc1
Not as bad as 23.1, but since:
 11.5 sewage pumping relay station at North Pines floods
 12.5 both Northside Drive and Southside Drive close
it could still be a pretty big disaster.
Maybe since the sewage infrastructure was repaired after 1/1997,
it will hold up better this time, but bad things can happen when there's a lot of water hammering things.
EdBannister

Mountain climber
13,000 feet
Jan 5, 2017 - 09:41pm PT
Gee current forecast is 15.9,

will anyone admit that this might mean the earlier forecasts, and the models were wrong?

When the forecasts were 23.1 and 23.7 i looked at the maps, and said my personal guess was under 17.

hmmmmmmm
Ken M

Mountain climber
Los Angeles, Ca
Jan 5, 2017 - 09:46pm PT
No, Ed, the earlier was not wrong.

BECAUSE IT HASN'T HAPPENED YET.

It might be exactly right.

These are only predictions, which become more likely accurate the closer we get.

But we don't know TRUTH until it happens.
EdBannister

Mountain climber
13,000 feet
Jan 5, 2017 - 09:49pm PT
Valid point Ken! if i had stated it absolutely,

you might want to reread

i wrote might mean, because it has not happened yet.

but you will be the first to say the models are not worth the time to look at them when it is under 17 feet, right?
or you might even apologize for yelling with caps when you had not read what i wrote.

Reilly

Mountain climber
The Other Monrovia- CA
Jan 5, 2017 - 10:15pm PT
this might mean the earlier forecasts, and the models were wrong?

More likely is that they're backing off so as to not look so foolish
claiming the sky is falling.

Regarding the sewage pumps, did they not learn anything in '97?
Did they not think it could happen again? I know it isn't their money
but isn't insanity the repetition of doing the same thing wrong?
Clint Cummins

Trad climber
SF Bay area, CA
Jan 5, 2017 - 11:11pm PT
In my view, the "model" is a series of calculations that starts with input data on current temperatures and pressures at multiple locations over the Pacific Ocean over time,
plus current snowpack estimates and computes a forecast at this particular bridge at time points in the future.

What the model does is predict temperature and precipitation amounts over the watershed area upstream from the bridge, and estimate how much snow will melt as well.
Then the model adds up the precip/melt at points on the grid and uses the distances and slopes to the bridge point to predict river height at each time point.
What has likely changed is the "input data", mostly the ocean temperatures and pressures.

Sophisticated predictions will also show a range of likely outcomes, which statisticians call a "confidence interval".
In this particular plot, we just see the point forecasts and not a range.
But it's likely that the range is output by the model and is just not shown on this plot.

I'm also not sure what "wrong" means.
It seems like 15.5, 15.9, 17, 23.1, etc. are all way bigger than 11.5 and 12.5,
so the prediction has been steady that this is likely to be a big event with damage and closures.
However, I don't know how damage might scale nonlinearly with the actual depth.
healyje

Trad climber
Portland, Oregon
Jan 6, 2017 - 12:41am PT
My guess is it's fairly dependent on how steady the jetstream speed and location hold. If it holds at a 140 over the Sierras then it's a good bet, if it weakens, wobbles or shifts then that will throw a wrench in the forecasts. Looking fairly solid at the moment and given the midwest forecasts call for the entrenching of the arctic air mass (polar vortex) over the northern half of the country I don't expect the jetstream to be changing much.





Ed Hartouni

Trad climber
Livermore, CA
Jan 6, 2017 - 01:32am PT
here's the historic record of the Pohono Bridge flow gauge going back to 1917

Reilly

Mountain climber
The Other Monrovia- CA
Jan 6, 2017 - 07:56am PT
The ol' Polar Vortex is another concoction of the effete elitist news media selling ad time.
It hasn't been below -20F in Fairbanks yet this winter. That's like spring up there.
WBraun

climber
Jan 6, 2017 - 08:04am PT
If the river goes to 12 the Valley can handle it as I've seen both times when it went that high.

El Cap bridge usually gets a heavy log jam there.

Devils elbow goes under water all the way to end of Elcap straight.

Chapel straight goes under water.

But 20 feet will be very very bad because it can take out the road/s in various places.



Ed Hartouni

Trad climber
Livermore, CA
Jan 6, 2017 - 09:50am PT

The ol' Polar Vortex is another concoction of the effete elitist news media selling ad time.
It hasn't been below -20F in Fairbanks yet this winter. That's like spring up there.

one is startled at the incredible stupidity of this remark, but apparently looking at the maps that healyje quoted above, and knowing where Fairbanks Alaska is on those maps, with respect to the jet stream configuration, apparently doesn't evoke any challenge to the emerging ipse dixit brigade on the STForum...

one is left to wonder just why we would expect any temperature anywhere to be different from what our notion of what that temperature should be...

the failure of logic is jaw dropping.

rottingjohnny

Sport climber
Sands Motel , Las Vegas
Jan 6, 2017 - 09:58am PT
Reilly calls em as he sees them... minus 20 but feels like minus 35...
Srbphoto

climber
Kennewick wa
Jan 6, 2017 - 10:02am PT
The ol' Polar Vortex is another concoction of the effete elitist news media selling ad time.
It hasn't been below -20F in Fairbanks yet this winter. That's like spring up there.

but it did hit =20 this morning in Baker City, OR
Prod

Trad climber
Jan 6, 2017 - 10:21am PT
one is startled at the incredible stupidity of this remark, but apparently looking at the maps that healyje quoted above, and knowing where Fairbanks Alaska is on those maps, with respect to the jet stream configuration, apparently doesn't evoke any challenge to the emerging ipse dixit brigade on the STForum...

one is left to wonder just why we would expect any temperature anywhere to be different from what our notion of what that temperature should be...

the failure of logic is jaw dropping.

Gotta love an Ed H smack down....

Prod.
healyje

Trad climber
Portland, Oregon
Jan 6, 2017 - 11:47am PT
The ol' Polar Vortex is another concoction of the effete elitist news media selling ad time.

You've obviously never lived in Chicago.
healyje

Trad climber
Portland, Oregon
Jan 6, 2017 - 12:28pm PT
It wasn't predicted because the idea of atmospheric rivers was still fairly new and the '97 storm probably woke everyone up to their potential...

The term atmospheric river was coined in a seminal scientific paper published in 1998 by researchers Zhu and Newell at MIT

An ARKStorm (for Atmospheric River 1000 Storm) is a hypothetical but scientifically realistic "megastorm" scenario developed and published by the United States Geological Survey, Multi Hazards Demonstration Project (MHDP).

kunlun_shan

Mountain climber
SF, CA
Jan 6, 2017 - 01:53pm PT
Apparently the Valley is closing at 5pm today, through at least Sunday.

http://www.sfgate.com/bayarea/article/Yosemite-Valley-to-close-in-advance-of-menacing-10840593.php

EdBannister

Mountain climber
13,000 feet
Jan 7, 2017 - 10:06am PT
Matt, did they revise it down to 10 feet yet?
John M

climber
Jan 7, 2017 - 10:19am PT
No need to be snarky Ed. You have to forgive Ken. He is dealing with some rather serious health issues. He hasn't said what exactly, but he did say he was having difficulties walking.

Latest river estimate is 17.2 feet. As of 10:15 AM Sat.

The progression.

23.4
15.2
16.1
17.6

Its all a matter of how this storm lines up.
EdBannister

Mountain climber
13,000 feet
Jan 7, 2017 - 11:34am PT
looking at the weather maps and radar,

There is a strong stable front...

but i still do not see enough moisture in the system to agree with models that still say 17.. ok.. the Park is closed, liability lawyers appeased.

we will see.

Sunday 5pm is the predicted crest..

here is the USGS interactive Pohono Bridge Gaging Station link:
https://waterdata.usgs.gov/ca/nwis/uv?11266500
rincon

climber
Coarsegold
Jan 7, 2017 - 11:52am PT
The drizzle finally changed to a steady rain here in the foothills. I doubt there's going to be a flood, but you never know. The Robin's outside my window don't care, there's a bunch of them eating Toyon berries all soaking wet. The gophers are loving it too. Soft earth means they can go anywhere they want! I saw our feral cat with one in his mouth earlier this morning.
survival

Big Wall climber
Terrapin Station
Jan 7, 2017 - 02:17pm PT
No eyewitness reports from the valley this afternoon yet?
ryankelly

Trad climber
Bhumi
Jan 7, 2017 - 02:36pm PT
[Click to View YouTube Video]

Valley is on lock down..

around 2pm today in front of the El Portal Market
WBraun

climber
Jan 7, 2017 - 02:52pm PT
Meh ... that's nothing.

At Pohono the river only went up a half a foot so far.

Ryan, I was just there right before you.

Do you know who's kayak that is across the river?

Got back up to the Valley with the rescue raft trailer and it started to hail.
ryankelly

Trad climber
Bhumi
Jan 7, 2017 - 03:00pm PT
Don't know about the kayak

I'm thinking this will be the "before" video and I'll do another one at 2 tomorrow afternoon
EdBannister

Mountain climber
13,000 feet
Jan 7, 2017 - 03:11pm PT
Hope you guys stay safe out there.

Is it cold enough to be snowing in the high country???
rincon

climber
Coarsegold
Jan 7, 2017 - 03:24pm PT
http://sierranewsonline.com/employees-evacuated-from-yosemite-valley/

"YOSEMITE — A mandatory evacuation notice has been issued for all non-essential personnel for the Yosemite Valley as of 4 p.m. today, according to a notice issued by the Mariposa County Sheriff’s Office."
WBraun

climber
Jan 7, 2017 - 03:27pm PT
EdBannister

So far so good. I don't want a replay of the 97 flood.

That really sucked ......
EdBannister

Mountain climber
13,000 feet
Jan 7, 2017 - 03:36pm PT
We hope the best for you and the Valley Werner!

I just viewed the webcam at the 8,000ft level, it is raining there now, not good.
Hoping that changes later tonight.
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Jan 7, 2017 - 03:51pm PT
I'm sitting here with the window wide open it's that warm.

There's been almost no rain since early this morning.

Fizzel-STicks!
EdBannister

Mountain climber
13,000 feet
Jan 7, 2017 - 04:41pm PT
Hate to say it but the last four hours the storm has consolidated, whatever the number was going to be, it is a little higher now, and, it is warm, both make for higher water
'Pass the Pitons' Pete

Big Wall climber
like Ontario, Canada, eh?
Jan 7, 2017 - 04:47pm PT
Hey Werner, did they kick you out?

Or are you "essential"?
rottingjohnny

Sport climber
Sands Motel , Las Vegas
Jan 7, 2017 - 04:53pm PT
He's on the merced jumping a shark...
aspendougy

Trad climber
Los Angeles, CA
Jan 7, 2017 - 05:33pm PT
Yes, the problem is this is a warm air mass. I am in L.A., it is dark and 70 degrees outside. Of course, we are further south, but it is the same air mass, and it's an extremely warm storm.
Clint Cummins

Trad climber
SF Bay area, CA
Jan 7, 2017 - 06:15pm PT
Latest river estimate is 17.2 feet. As of 10:15 AM Sat.

The progression.

23.4
15.2
16.1
17.6

Its all a matter of how this storm lines up.
Current forecast (as of Sat. 1:56pm) is 18.4 feet peak height (20kcfs) at Pohono Bridge on Sunday around 5pm.
So the forecast has moved up again back towards the initial estimate.
http://water.weather.gov/ahps2/hydrograph.php?wfo=hnx&gage=pohc1
And the graph suggests the height will be above 12.5 starting at around 1am Sunday, until around 10pm Sunday, so that's 21 hours above 12.5 (10kcfs).
Wise move to close the Valley on Friday night, to reduce distractions / rescues.
crusher

climber
Santa Monica, CA
Jan 7, 2017 - 06:53pm PT
Stay safe Werner and keep us posted if you can. Fingers crossed...
john hansen

climber
Jan 7, 2017 - 06:57pm PT
A good map for 24 hour rain totals. It updates every hour.
Looks like about 2.21 in Yosemite from 4pm friday to 4pm today



http://www.cnrfc.noaa.gov/precipMaps.php?group=nca&hour=24&synoptic=0
ß Î Ø T Ç H

Boulder climber
ne'er–do–well
Jan 7, 2017 - 08:36pm PT
[Click to View YouTube Video]
John M

climber
Jan 7, 2017 - 09:19pm PT
They moved the prediction up to 19.7 feet. Major flood is 20. This could be pretty bad.

http://water.weather.gov/ahps2/hydrograph.php?wfo=hnx&gage=pohc1
neebee

Social climber
calif/texas
Jan 7, 2017 - 11:41pm PT
hey there say, john m... just got on line fast, as, i been worried about my friends, etc, in various parts of calif and yosemite, of course, and--nevada, as well..


thanks for the update...
well, got to get going now, may get to check back tomorrow, thanks
again, all you that are keeping this updated... oh my...

prayers for any that have to be out there doing work, in any of this...

hey there, say, to werner and all... oh my...



edit:
http://www.sierrastar.com/news/local/article125170134.html

http://www.sierrastar.com/news/local/article124969924.html
Clint Cummins

Trad climber
SF Bay area, CA
Jan 8, 2017 - 03:47am PT
Latest forecast is lower: 15.8 feet max height (forecast as of 1:59am Sunday).
SalNichols

Big Wall climber
Richmond, CA
Jan 8, 2017 - 04:48am PT
In Richmond we get periodic squalls with a lot of rain. Right now its light rain being propelled by 45 kt winds. Holy hell its windy.
EdBannister

Mountain climber
13,000 feet
Jan 8, 2017 - 07:29am PT
for 7 am Sunday even the most recent revised model showed a predicted discharge of 7,200 CFS

actual flow 3,219...

NOAH, at 7am, is 223% of reality.

so we hope the trend continues


SalNichols

Big Wall climber
Richmond, CA
Jan 8, 2017 - 07:33am PT
In 97 the SF American hit 300,000 cfs. That's a bunch of H2O.
John M

climber
Jan 8, 2017 - 08:19am PT
At 2 AM last night it was predicted to be 19.7, but you could see on the radar that the main plume of moisture had moved north. Like I said, its all about where the plume hits California.
neebee

Social climber
calif/texas
Jan 8, 2017 - 09:01am PT
hey there say, thanks guys...
:)
EdBannister

Mountain climber
13,000 feet
Jan 8, 2017 - 09:49am PT
Crest forecast is 12.1 now

still think 10 is a better number.

Ken M

Mountain climber
Los Angeles, Ca
Jan 8, 2017 - 10:03am PT
Looks like the worst is averted, thank God.

I'm sure that Werner and the others are out filling sandbags and protecting infrastructure as best they can. Hope they are safe. Good to know they know what they are doing.

It feels like it was simply the luck of God that the worst of the storm veered north (and how are those folks?). It will not always be so. So we didn't lose $300,000,000 in infrastructure THIS TIME. You'd think it might be worth spending a few mill for planning and infrastructure hardening to protect against the next one which WILL HAPPEN.
Matt Sarad

climber
Jan 8, 2017 - 10:17am PT
The Kern River is flowing through Bakersfield for the first time in years. It looks like a filthy, foaming, shitty mess full of homeless camp detritus, trash, diapers, and corpse juice from a recent suicide in Hart Park.
EdBannister

Mountain climber
13,000 feet
Jan 8, 2017 - 10:23am PT
Yes Ken, it has come repeatedly in the past, it is why the Valley is flat on the bottom.

70 thousand years ago there was global warming, then stability, then warming, and stability, then warming, then stability.. we have the record in the rocks, unsorted unconsolidated piles of rocks, 1 terminal, and three recessional moraines dam the valley at different points and have since been silted in by floods. Hence Yosemite, because of repeated floods, is flat on the bottom instead of the classic glacial valley U.

k-man

Gym climber
SCruz
Jan 8, 2017 - 10:28am PT
That's me, always cutting and pasting from a friend:

The Flood Warning continues for the Merced River at Pohono Bridge.

* At 8:00 AM Sunday the stage was 7.3 feet
* Minor Flooding is forecast
* expected to rise above flood stage of 10.0 ft this afternoon then
forecast to crest near 12.0 ft tonight then forecast to fall below
flood stage of 10.0 ft early tomorrow then forecast to recede to
near 8.5 ft tomorrow morning.
* Flood Stage 10.0 ft
* IMPACT...Near 12.5 feet, Northside Drive and Southside Drive, which
are the main roads in Yosemite Valley, become flooded and are
closed to traffic.
* IMPACT...Near 11.5 feet, Sewage pumping relay station at North Pines
Campground becomes flooded.
* IMPACT...Near 10.5 feet, Water tops the swinging bridge downstream
from Chapel Meadow. Overflow from Woski Pond floods access road.
* IMPACT...Near 10.0 feet, Western portion of North Pines Campground
located at the east end of Yosemite Valley between the confluence
of the Merced River and Tenaya Creek begins to flood. Water rises
to the base of the swinging bridge downstream from Chapel Meadow.
* IMPACT...Near 9.5 feet, Portion of Lower Pines Campground becomes
flooded. Limited site-specific evacuations begin at Housekeeping
Camp located along the south-facing bank of the Merced River.
(Upstream from Sentinel Bridge and downstream from Stoneman Bridge)
* IMPACT...Near 9.0 feet, Chapel Meadow (south side of river) and
Cooks Meadow (north side of river) begins to experience overflow.
Mark Force

Trad climber
Ashland, Oregon
Jan 8, 2017 - 11:21am PT
In 97 the SF American hit 300,000 cfs.

Holy shit!
Eric Beck

Sport climber
Bishop, California
Jan 8, 2017 - 12:34pm PT
Here in Bishop this is not a warm storm. Currently 35 with a half inch of icy slush everywhere. It may be that it is somewhat warmer higher up with the cold air trapped in the bottom of the valley.

My rain gauge shows 25mm so far, yesterday and today. A light rain continues. This stuff reminds me of my worst memories of winter in Ann Arbor when I was little, cold and slush everywhere.
EdBannister

Mountain climber
13,000 feet
Jan 8, 2017 - 02:25pm PT
2 pm pacific coast time USGS lists 9.23 feet as Merced River level at the Pohono Bridge gaging station.
https://waterdata.usgs.gov/ca/nwis/uv?11266500

More significant, the rate of increase has slowed at least for the last hour, to less than .2 feet per hour.

If, and only if that continues or decreases, the crest could be close to 10 feet.



As a comparison to the American River in 1997, Merced River discharge was 24,600 Cubic Feet per second. The American, as measured at Fair Oaks, drains nearly 1,800 square miles.. The Merced Drainage basin as measured at Pohono Bridge is 321 square miles.
rincon

climber
Coarsegold
Jan 8, 2017 - 02:52pm PT
Mammoth Pool Reservoir today
EdBannister

Mountain climber
13,000 feet
Jan 8, 2017 - 02:53pm PT
Model projection revised down to 11.8 feet

Incredibly, they are still projecting a .5 foot increase next hour, and .3 per hour thereafter.
EdBannister

Mountain climber
13,000 feet
Jan 8, 2017 - 03:11pm PT
3pm USGS published gaging station data:

9.25 feet

In the last hour, stage, or water level went up .02 feet, that is two one hundreths of one foot.
The model generated change was a .5 foot increase.

Noah also still predicts 11.8 feet for the crest, around midnight.....
Ricky D

Trad climber
Sierra Westside
Jan 8, 2017 - 03:12pm PT
Rincon from Coarsegold - how far up the road did you get?

You appear to be on the open ridge just before the Mile High turnout which would put you around 5300 feet.

Has the snow from last week melted off to that point?



Clint Cummins

Trad climber
SF Bay area, CA
Jan 8, 2017 - 03:31pm PT
Ed,
Thanks for sharing your insights.
I agree, it's not a good sign for the model that there is a jump from the current measured level to the closest forecast point.
Looks like it won't go over 12.5 after all.

I wonder what factors changed the forecast in the past 24 hours -
path of the storm, maybe?
As you said, the Merced watershed is fairly small, so if the storm changes track to north or south, it could miss some or all of the watershed.
WBraun

climber
Jan 8, 2017 - 03:34pm PT
Who knows what's gonna happen.

It could get very bad.

It's dumping sh!t cakes hard right now again.

You should see and hear Yosemite falls, it's unreal right now.

It's not looking good that's fer sure ......
EdBannister

Mountain climber
13,000 feet
Jan 8, 2017 - 03:37pm PT
It's dumping sh!t cakes hard right now again.

Funniest thing i have seen in weeks...

OK Mr. Braun, we hope you are, and continue to be safe.

so, we wait and watch.
ron gomez

Trad climber
fallbrook,ca
Jan 8, 2017 - 03:52pm PT
Hey Werner hope you and Merry are well.
Peace
rincon

climber
Coarsegold
Jan 8, 2017 - 04:38pm PT
"Rincon from Coarsegold - how far up the road did you get?

You appear to be on the open ridge just before the Mile High turnout which would put you around 5300 feet.

Has the snow from last week melted off to that point?
"

No snow to that point, but just around the corner the road had snow on it. That's as far as I went. The snow was solid ice from being rained on.



Your welcome DMT!
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Jan 8, 2017 - 05:00pm PT
Eric Beck, the warm storm is at LOWER ELEVATIONS than Bishop's.
This maybe could be why you aren't feeling the tropic glow like I am over to the SJV and a mile lower.
ryankelly

Trad climber
Bhumi
Jan 8, 2017 - 05:14pm PT
[Click to View YouTube Video]

9.4 feet and 6,000 cfs at Pohono Bridge / 6 feet and 2,170 cfs at Happy Isles

forecast is for almost 12 ft at Pohono...
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Jan 8, 2017 - 06:01pm PT
Hoorayin' for Ryan the K! Yowsah!
neebee

Social climber
calif/texas
Jan 8, 2017 - 06:04pm PT
hey there say, werner... thanks for the share...

prayers for all...

here is a link, showing three rivers, the cosumnes, the yuba, and the
american... and a bit of yosmite...

http://www.sacbee.com/news/weather/article125196579.html



limpingcrab

Trad climber
the middle of CA
Jan 8, 2017 - 06:10pm PT
I think the storm turned further north than anticipated. Totally missed the Kaweah watershed today. It got up to 13,000 cfs at midnight last night and was down to 5,000 by the time I checked it out at 1:00 today. It was super warm and muggy, if the precip did come this way it would have melted everything out and been quite a show.

kaholatingtong

Trad climber
The real McCoy from The City
Jan 8, 2017 - 06:14pm PT
The yuba is going big right now. South fork here, a friends picture, https://m.facebook.com/wakingcrowphotography/
EdBannister

Mountain climber
13,000 feet
Jan 8, 2017 - 07:30pm PT
USGS just revised 7:00 reading to 10.01 for Pohono

https://waterdata.usgs.gov/ca/nwis/uv?11266500
ß Î Ø T Ç H

Boulder climber
ne'er–do–well
Jan 8, 2017 - 07:34pm PT
Majid_S

Mountain climber
Karkoekstan
Jan 8, 2017 - 07:36pm PT
Werner

put some air in the yellow boat and get it ready for plan B
Mighty Hiker

climber
Outside the Asylum
Jan 8, 2017 - 07:39pm PT
Looking at the bright (?) side, think of all the garbage and stuff that this is uncovering for the 2017 Yosemite Facelift. And all the litter and junk that's being flushed clean out of the Valley - not that that is necessarily better.
WBraun

climber
Jan 8, 2017 - 07:45pm PT
Majid

It just hit 10 feet at Pohono Bridge, plus it's still raining very hard.

We'll see what happens by tomorrow morning.

It will probably hit 12 feet by Monday morning?

The Park is in hard closure mode.

No one in and no one out except by authorized personnel and escort for News media etc.
EdBannister

Mountain climber
13,000 feet
Jan 8, 2017 - 08:19pm PT
8pm reading at Pohono 10.27

water about to splash on the swinging bridge
Majid_S

Mountain climber
Karkoekstan
Jan 8, 2017 - 09:02pm PT
Werner

what is the name of that big rock passed the flat rock downstream from pohono? Is that under water?
EdBannister

Mountain climber
13,000 feet
Jan 8, 2017 - 09:09pm PT
10.83 at 9pm

Lower and North Pines Campgrounds partly flooded.
The Swinging Bridge is awash.
Road to west entrance flooded.

Werner gets overtime?


11.18 at 10:00 pm sunday previous hour increased .35

hope everyone stays safe.

11.49 at 11:00 pm




neebee

Social climber
calif/texas
Jan 9, 2017 - 05:38am PT
hey there say, ... you can type in the name of your area, and this
link, puts a lot of good shares, about how the rivers, etc, are,
in your area...

plus other info, etc...
i just picked the el portal area...

https://www.wunderground.com/cgi-bin/findweather/getForecast?query=El+Portal%2C+CA


THIS is the flood warnings, from that page...
https://www.wunderground.com/US/CA/096.html#FLO


HIT THE WINTER STORM WARNING, link, on the page...
it should give you this:

https://www.wunderground.com/US/CA/096.html#WIN
EdBannister

Mountain climber
13,000 feet
Jan 9, 2017 - 06:31am PT
looks like finally a crest at 5 am 12.68

12.5 at 6am and hopefully quickly down.


thanks neebee
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Jan 9, 2017 - 07:45am PT
Is this like a 90-year flood, then? Sounds like.

Werner sounds sterner today..."hard closure mode."

Anders, my precious, think of all the Au coming down the rivers, too.

rincon

climber
Coarsegold
Jan 9, 2017 - 08:30am PT
Bass lake is filling up fast! They're on alert for flooding in North Fork.

http://sierranewsonline.com/pre-evacuation-advisory-issued-for-north-fork-as-waters-rise/

http://basslakeca.com/camera1.html
Ken M

Mountain climber
Los Angeles, Ca
Jan 9, 2017 - 09:06am PT
Actual mandatory evac for parts of Bass Lake:

http://sierranewsonline.com/portions-of-north-fork-evacuated-as-creeks-overflow/
G_Gnome

Trad climber
Cali
Jan 9, 2017 - 12:45pm PT
Are there still giant goldfish in Bass Lake?
Clint Cummins

Trad climber
SF Bay area, CA
Jan 9, 2017 - 03:50pm PT
To recap what Ed noted, the crest was at 12.68 feet,
and it's back under 10 now.
http://water.weather.gov/ahps2/hydrograph.php?wfo=hnx&gage=pohc1
Reilly

Mountain climber
The Other Monrovia- CA
Jan 9, 2017 - 04:46pm PT
So does that mean the Brown Trout aren't spawning?
Ken M

Mountain climber
Los Angeles, Ca
Jan 9, 2017 - 09:25pm PT
Pretty good article on the damage, with pictures:

http://www.sfgate.com/science/article/Rockfall-blocks-Highway-140-into-Yosemite-but-10845837.php
Ken M

Mountain climber
Los Angeles, Ca
Jan 9, 2017 - 09:39pm PT
I've been giving thought to what mitigation could be done as a preventive measure in Yos Valley. As I think about the natural forces, what is happening over time is that the river bottom gradually rises, as it has for thousands of years. As pointed out, that is why the valley is flat.

Each time it rains, and as time goes on, the river slightly rises. yes, when we get a blast like this, stuff gets blasted out---but not the boulders. They accumulate from the cliffs, above, then get filled in with smaller stuff over time.

Effectively, everything else in the valley is becoming lower, compared to the bottom of the river, effectively making it more susceptible to flooding.

There are only two ways in which this can be dealt: Raise everything else, which would be a massive building project, or lower the river through dredging. I'm no expert in either. I would imagine that dredging the Merced would require an unholy experience of EIR's and permits.

Out of Marina del Rey, where I sail, we have a similar problem with silting out of the harbor entrance by sand, and every few years it has to be dredged to remain navigable. I envision a similar, regularly repeated process.

I have no idea if such a thing is practical.

Otherwise, we will be spending $300 mill from time to time to fix what has been destroyed by flood.
EdBannister

Mountain climber
13,000 feet
Jan 9, 2017 - 11:01pm PT
Ken,

Marina Del Rey needs dredging because wave action carries sand from north to south.
This is not at all the same process as is at work in the Valley.

The long long term is the Merced should incise the moraines,
There will not be a depositing braided stream in our lifetime or the next.
Floods like what we just had lower, rather than raising the streambed, nature's dredge.

It rained a lot, the river rose, Yosemite is geographically weird because of recessional moraines,
so i guess we could call it a pseudo floodplain... but, you do not need to bring a dredge because the stream is not at grade, it is too steep in the long long term, it has to erode it's way down to a couple hundred feet above the elevation of Merced.. but that will take a while...
Ed Hartouni

Trad climber
Livermore, CA
Jan 9, 2017 - 11:38pm PT
Otherwise, we will be spending $300 mill from time to time to fix what has been destroyed by flood.

don't fix it... eventually human construction will be washed out of the Valley which would then return to its wilderness state...

that would be wonderful.
Ed Hartouni

Trad climber
Livermore, CA
Jan 10, 2017 - 12:46am PT
in 1864 Bierstadt made this painting of Yosemite Valley:


the terminal moraine that caused the dramatic lake, which seems a fantasy to our modern eyes when looking at that painting, was blasted in 1897... you can walk the moraine starting at the "wood lot" turnout just beyond the western end of El Cap Meadow as you are heading west on Northside Dr.

The high point of the moraine is about 3975' on Google Earth. If you draw a polygon with that contour you would get the "lake"


and seeing that, you get an idea of what Bierstadt could have seen on one of his trips to the Valley. Of course he did rearrange the features a bit, and steepened them a bit... but he likely took the view from the vicinity of Devil's Elbow...

Interestingly, the Valley floor is drier now, and the pines have marched in, you can see the oaks in the painting, and not many pines... and in the GE image, you can see the mottled effect of lower tree density in the "lake" area.

mcreel

climber
Barcelona
Jan 10, 2017 - 06:29am PT
Super interesting post, Ed!
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Jan 10, 2017 - 06:54am PT
Shows that A.B. knew where to find the center of the universe.
Ken M

Mountain climber
Los Angeles, Ca
Jan 10, 2017 - 03:22pm PT
Ed B, when you wrote:

and incredibly, there is no threat listed for Monday... warmer rain... i don't get it

And:

it was after satellites and doppler dingus...

let's just watch what happens,
and you can tell me i told you so if it gets to 23 feet on sunday,
and i will tell you the models suck if it never tops 19 feet.

personal prediction, not over 17 feet, what is your number Dingus?


and what if the real high comes on Monday, where my concern is,
and the model boys raise no concern...

I must admit I was frosted. You were expecting precise, exact predictions. In fact, it DID flood, and it flooded at pretty much the exact time that it said that it would. And it did NOT have a high flow on monday, when you predicted that there would be one. The model boys were right, and you correctly stated that "you don't get it".

Neither do I, because this is not my area of training. But I don't casually dismiss the efforts, professionalism, and training of the "model boys", who did a great job of giving a warning to our brothers in the Park, and probably averted a lot of misery by their efforts. I don't particularly like people attacking even snarkiliy, one of the Uniformed Services of the United States in the performance of their duties.

If I offended you by standing up for them, I apologize.
Mighty Hiker

climber
Outside the Asylum
Jan 10, 2017 - 03:35pm PT
"Geology Underfoot in Yosemite National Park" (Stock & Glazner) has an entire chapter on the El Capitan moraine.

"During winter floods and spring runoff, the river (Merced) backed up against the moraine, flooding the Valley and leaving large areas of standing water. This affected the ever-increasing human use of the Valley, closing roads and trails, washing out bridges, isolating hotels and cabins, and flooding the meadows..."

The narrows formed by the moraine was the location of the first El Cap bridge, built in 1878. There were rapids at that point, formed by the moraine, and so they blasted the rocks in the rapid, to lower the river's level. (Presumably at low water.)

"Subsequent investigations of the El Capitan moraine suggest that the blasting lowered the river level by 3 to 5 feet, and ripple effects, such as the deepening of tributaries and lowering of groundwater levels, propagated far upstream of the moraine. The extent of flooding in eastern Yosemite Valley during the 1997 flood was so great largely due to water backing up behind this relict of the most recent glaciation."

As Ed observes, just an eyeblink in the geological history of the Valley. Sooner or later another blockage will occur, caused by flooding, rockfall, or otherwise.
Ken M

Mountain climber
Los Angeles, Ca
Jan 10, 2017 - 03:43pm PT
Thanks, MH.

As I've stated, I'm not an engineer, so don't have the background to fully understand the dynamics of the situation.

It does sound as though the blasting of the moraine averted a great deal of flooding in the intervening years, saving many millions of dollars of damage.

It may be that the laws have evolved to make such mitigation impossible, legally. It may also be unworkable hydraulically.

It's just hard to imagine that there might not be a way to mitigate some of the risk, if there were actual professional effort and fund spent to systematically evaluate the options.
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Jan 10, 2017 - 03:54pm PT
The El Cap terminal moraine is clearly visible on this LIDAR imagery


from this website...

http://www.opentopography.org

Under the DATA tab Select GoogleEarth Files from the pull down menu
Mighty Hiker

climber
Outside the Asylum
Jan 10, 2017 - 04:11pm PT
Hydrology is a complicated thing, but in the case of the Valley it seems fairly simple. It's nearly flat, with a partial dam west of El Capitan. Its catchment basin is very large, ranging from (about) 1,200 m to well over 3,000 m. If enough water comes into it from above, whether due to snowmelt, heavy rain, or both, it will flood.

Almost all buildings, road and facilities are on the Valley floor, and so subject to flooding - as they are to rockfall. Many of them are also fairly old... It would probably be vastly expensive to flood-proof even the more important and valuable structures, and the services on which they depend - water, sewer, power, communications - would still be vulnerable. (Many key Yosemite services are behind the village, and so somewhat uphill and less exposed.)

If you could blast a bigger hole in the El Capitan moraine, it may simply mean that the water floods through faster, and causes more damage downstream, e.g. in El Portal.

I wonder how this has affected Camp 4?

FWIW, the forecast here is for more cold weather through Thursday - another shot of Arctic air. Followed by warming and damp weather through next week.
WBraun

climber
Jan 10, 2017 - 04:25pm PT
with a partial dam west of El Capitan.

Where is this dam?

The Merced river dam at 140 and 120 junction was removed years ago ....
Mighty Hiker

climber
Outside the Asylum
Jan 10, 2017 - 04:51pm PT
The "dam" is the remnants of the El Capitan moraine. Greg's book says it acted as a dam in 1997.
neebee

Social climber
calif/texas
Jan 10, 2017 - 05:13pm PT
hey there, say, ed... it was very interesting seeing your post on THIS:

in 1864 Bierstadt made this painting of Yosemite Valley:



I HAVE this print, though, it is very dull and old,
HERE IS copy from the website...

your 'water' reminded me of the water in mine, though,
mine may NOT be relevant...

it was just a fun reminder of these works...

and--
interesting, of COURSE, on what you mentioned...



cragnshag

Social climber
san joser
Jan 10, 2017 - 05:29pm PT
Make Yosemite Great Again.

Rebuild the El Capitan Terminal Moraine!
Kalimon

Social climber
Ridgway, CO
Jan 10, 2017 - 07:35pm PT
The Donald is proposing a name change to "El Putitan" . . . so get ready to amend all those references.
krahmes

Social climber
Stumptown
Jan 10, 2017 - 08:53pm PT
So Ed posted of a painting by Albert Bierstad as some proof that once there was a large lake in Yosemite Valley in the 19th century. I really don’t have a dog in the question as to whether there was a lake there. Mulholland certainly would have like to put one there, but the painting immediately made me think of picture of Mount Hood that hangs in the Portland Art Museum that has always puzzled me in that however grand WyEast is, it does not look this from any angle:

The painting is a Bierstad from 1869 and quick check online came up with this explanation.

“Albert traveled the west and upon spending time in Oregon, he wanted to convey the beauty of Mt. Hood and the landscape to the people living in eastern U.S. He purposefully compiled a few different angles of the mountain and landscape onto painting, in order for others to visualize and take in the beauty of the Pacific Northwest, that is why do not recognize this specific scenery.”
https://ruslanp.wordpress.com/2014/01/28/art/

It is a beautiful piece of art, I look at it every time I go to the art museum it has lot of truth, but it is unreliable as a document on which to base how things were.
EdBannister

Mountain climber
13,000 feet
Jan 10, 2017 - 09:52pm PT
Ken,

yes i said i was concerned about Monday, and i was wrong to have a concern.
But it was a concern about a threat, i assigned no number, made no prediction for Monday.


NOAH Predicted discharge was originally about 23,000 cfs
actual peak discharge was about 10,000 cfs

Do you look at the fact that the estimate was 230% of reality?

Is there some percent error amount at which you will say they were wrong?
To me, a more than double inaccuracy, is inaccurate.


Yes, early warning was good, and we all hope for the safety and well being for all.

But will the people on the ground take the next number they are given seriously??
Probably not, I did not this time, and i was correct not to do so.

I looked at weather maps and radar and estimated less that 17 feet when the estimate was 23.1 feet.
You can't undo that.

Clint Cummins

Trad climber
SF Bay area, CA
Jan 10, 2017 - 10:13pm PT
A estimate like 23.1 (several days in advance) is why they should provide a range (like a 95% confidence interval), along with the estimate.
That way we get an idea of how uncertain the estimate is.
The model may have provided such a range.
But we did not see a range on the graph we kept looking at.
EdBannister

Mountain climber
13,000 feet
Jan 10, 2017 - 10:20pm PT
yes Clint,

but in order for a range to have been correct, they would have needed to say:

23,000 cfs plus or minus 13,000



What do you think?

Estimates with a range greater that 50% might not be estimates.

and to have the lack of comprehension to publish three significant figures i.e. 23.1, is laughable when your number is more than 50% inaccurate... sorry.
Mighty Hiker

climber
Outside the Asylum
Jan 10, 2017 - 10:20pm PT
Bierstadt's 1860s painting of the Valley may have employed some artistic licence, but can't be much of a stretch. The "Lake Yosemite" (seasonal) of that era is well-documented. There are still numerous ox bows and pools on the river, which can be much larger in spring.
EdBannister

Mountain climber
13,000 feet
Jan 10, 2017 - 10:28pm PT
The moraine arching between El Capitan and Bridalveil falls was blasted to make the Valley more attractive to tourists, it drained mosquito habitat.
Clint Cummins

Trad climber
SF Bay area, CA
Jan 10, 2017 - 10:48pm PT
Ed B,
Yes, a +/- type standard error of forecast would be a start.
Although with phenomena that can't be negative, it's better to have
an asymmetric confidence interval.

This type of graph is a nice way to show the uncertainty of a forecast
(dark blue region: 80% chance the interval will contain the actual;
light blue region: 95% chance the interval will contain the actual).
Ed Hartouni

Trad climber
Livermore, CA
Jan 10, 2017 - 10:49pm PT
I don't take Bierstadt's paintings as "proof" of the lake, his "production pieces" used elements of oil "sketches" he made, those sketches are quite accurate... though may be missing trees in the foreground...

And putting elements together in a painting, or in a photograph, are/were standard for displaying the "feel" of the place.

But that particular painting meshes well with the El Cap Nose base, Schultz's Ridge and Manure Pile and the contour line of the moraine's height (current height).

Dewey Pt. is missing, Lost Brother moved, and the south rim has been moved back to provide a separation from the spires whose aspect ratio is certainly a bit higher than tall... but you can still imagine Brower's Route on Lost Brother in that painting...

I am well aware of the liberties Bierstadt took in interpreting the western landscape... but they were based on his sketches and his experiences when traveling what was at the time a rather remarkable adventure.
Ken M

Mountain climber
Los Angeles, Ca
Jan 10, 2017 - 10:57pm PT
Ken,

yes i said i was concerned about Monday, and i was wrong to have a concern.
But it was a concern about a threat, i assigned no number, made no prediction for Monday.


NOAH Predicted discharge was originally about 23,000 cfs
actual peak discharge was about 10,000 cfs

Do you look at the fact that the estimate was 230% of reality?


No, I look at the fact that WELL IN ADVANCE, they predicted a flood. There WAS a flood.




Is there some percent error amount at which you will say they were wrong?
To me, a more than double inaccuracy, is inaccurate.


Yes, early warning was good, and we all hope for the safety and well being for all.

But will the people on the ground take the next number they are given seriously??
Probably not, I did not this time, and i was correct not to do so.

If you did not this time, you are saying that you ignored the warnings, and ventured into closed yosemite. If you had, you would have gotten into trouble.

You were WRONG not to do so. If they USPS had not acted on this warning, there would have been a lot of trouble with people caught in the flood.

The system worked.

What you're saying is that the SCUD missle warning system says that there are 30 missles heading in, and you're all upset because only 5 actually came in, and you don't think that you should have been told to get in the shelter. Fine. Don't.

With your "monday" prediction, you demonstrate that you don't have a handle on any of this stuff, so if you want to take your life in your hands, fine, but stop advising the rest of to dispense with belaying.
Ken M

Mountain climber
Los Angeles, Ca
Jan 10, 2017 - 11:01pm PT
A estimate like 23.1 (several days in advance) is why they should provide a range (like a 95% confidence interval), along with the estimate.
That way we get an idea of how uncertain the estimate is.
The model may have provided such a range.
But we did not see a range on the graph we kept looking at.

Clint, that is a reasonable point.

To that point, if you actually click on the link in the OP, it takes you to the graph, with a list of windows at the top, the rightmost of which says:

"Probability Information"

If you click on it, it gives you the range in a graphical form.

I don't think we can blame the NOAA if people don't use the data that they supply?
Clint Cummins

Trad climber
SF Bay area, CA
Jan 10, 2017 - 11:09pm PT
Thanks, Ken.
I should have looked for that earlier; I'm curious about what it showed, say on Wednesday!
http://water.weather.gov/ahps2/probability_information.php?wfo=hnx&gage=pohc1

Unfortunately, it is on a weekly level, instead of hourly,
so it does not give us that much info on how uncertain their hourly forecast was.
Ed Hartouni

Trad climber
Livermore, CA
Jan 10, 2017 - 11:24pm PT
you can also learn more here:
http://www.nws.noaa.gov/os/water/ahps/resources/Hydrologic_Web_Products_Manual.pdf

Ed Hartouni

Trad climber
Livermore, CA
Jan 10, 2017 - 11:26pm PT
see also

http://www.cnrfc.noaa.gov/graphicalRVF.php?id=POHC1

tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Jan 10, 2017 - 11:30pm PT
FYI, geologic map of Yosemite Valley Quaternary deposits showing Wisconsin stage terminal moraines that served as natural dams to form Lake Yosemite...

Full map here w/Legend including descriptions of each geologic units...
https://www.nature.nps.gov/geology/inventory/publications/map_graphics/yose_geology_overview_sheet3.pdf

Ed Hartouni

Trad climber
Livermore, CA
Jan 10, 2017 - 11:33pm PT
also this graph
http://water.weather.gov/ahps2/probability_information.php?wfo=abr&gage=pohc1&graph_id=2

with additional information available by clicking "About this graph"

http://water.weather.gov/ahps2/pdf/period_terminology.pdf
Ed Hartouni

Trad climber
Livermore, CA
Jan 10, 2017 - 11:59pm PT
the forecasts are here:

http://www.cnrfc.noaa.gov/arc_search.php

In the "Select Archive Product" box you want to select:

Product: RNORVFSJ - San Joaquin River Forecast [7/2010]

choose for January 2017




you get a list of files for each day with a forecast, e.g.:

FGUS56 KRSA 011655
RVFSJ

SAN JOAQUIN RIVER SYSTEM FORECAST
NATIONAL WEATHER SERVICE / CALIFORNIA-NEVADA RFC / SACRAMENTO CA
CALIFORNIA DEPARTMENT OF WATER RESOURCES / SACRAMENTO CA
854 AM PLT SUN JAN 01 2017

NEXT ISSUANCE: MONDAY, JANUARY 02, 2017 AT 9AM PLT

FORECASTS THROUGH: FRIDAY, JANUARY 06, 2017 AT 4AM PLT

ATTENTION... THE FOLLOWING STAGES OF PARTICULAR SIGNIFICANCE
HAVE OCCURRED OR ARE FORECAST TO OCCUR:
MONITOR STAGE
COSUMNES RIVER - MICHIGAN BAR (MHBC1) IN 113 HRS

***
SPECIAL NOTES-
***

RIVER
LOCATION STAGE FLOW TIME DATE LEAD
(NWSLI) (FT) (CFS) (PT) (MM/DD/YY) TIME
-------------------- ----- -------- ---- ----------

MERCED RIVER OBS 2.9 311 AT 8AM 01/01/17 (24)
POHONO BRIDGE >FS 10.0 NOT EXPECTED
(POHC1) MAX 3.5 554 AT 8AM 01/05/17 IN 95 HRS


on Friday Jan 6 at 3pm they had:

MERCED RIVER OBS 3.6 599 AT 8AM 01/06/17 (24)
POHONO BRIDGE >FS 10.0 BY 8AM 01/08/17 IN 47 HRS
(POHC1) MAX 16.2 16,700 AT 5PM 01/08/17 IN 56 HRS


Sunday morning at 3am they posted the highest prediction:

MERCED RIVER OBS 5.1 1,490 AT 7PM 01/07/17 (24)
POHONO BRIDGE >FS 10.0 BY 5AM 01/08/17 IN 9 HRS*
(POHC1) MAX 19.7 21,600 AT 4PM 01/08/17 IN 20 HRS*


Clint Cummins

Trad climber
SF Bay area, CA
Jan 11, 2017 - 03:31am PT
Thanks, Ed H.
I found a file with the basic data that generated the graph that Matt posted at the start of this thread -
it's from January 4th at 2:18pm.
http://www.cnrfc.noaa.gov/archive/2017/Jan/rvfsj/RNORVFSJ.20170104.2220z
It has the points that construct the graph, with a max height 23.1 at 5pm on 1/8
(99 hours in the future from when the forecast was made).
Data looks like:

218 PM PLT WED JAN 04 2017
...
MERCED RIVER OBS 3.2 405 AT 2PM 01/04/17 (24)
POHONO BRIDGE >FS 10.0 BY 7AM 01/08/17 IN 89 HRS
(POHC1) MAX 23.1 24,400 AT 5PM 01/08/17 IN 99 HRS
...
.A POHC1 20170104 Z DH22/HG 3.2
.ER POHC1 20170104 Z DH23/DC201701042210/DUE/HGIFE/DIH01
.ER1 3.2/ 3.3/ 3.3/ 3.4/ 3.4/ 3.5/ 3.5/ 3.6/ 3.7/ 3.7/
.ER2 3.8/ 3.8/ 3.9/ 3.9/ 4.0/ 4.0/ 4.1/ 4.1/ 4.1/ 4.1/
.ER3 4.1/ 4.0/ 4.0/ 4.0/ 4.0/ 3.9/ 3.9/ 3.9/ 3.8/ 3.8/
.ER4 3.8/ 3.8/ 3.7/ 3.7/ 3.7/ 3.7/ 3.6/ 3.6/ 3.6/ 3.6/
.ER5 3.6/ 3.6/ 3.5/ 3.5/ 3.5/ 3.5/ 3.5/ 3.5/ 3.4/ 3.4/
.ER6 3.4/ 3.4/ 3.4/ 3.4/ 3.4/ 3.4/ 3.4/ 3.4/ 3.3/ 3.3/
.ER7 3.3/ 3.3/ 3.3/ 3.3/ 3.3/ 3.3/ 3.3/ 3.3/ 3.3/ 3.3/
.ER8 3.3/ 3.3/ 3.3/ 3.3/ 3.3/ 3.3/ 3.4/ 3.4/ 3.4/ 3.5/
.ER9 3.6/ 3.9/ 4.2/ 4.7/ 5.3/ 5.7/ 7.4/ 9.2/ 11.7/ 13.3/
.ER10 14.7/ 16.0/ 17.2/ 18.0/ 18.8/ 19.8/ 21.0/ 22.7/ 23.1/ 22.5/
.ER11 21.8/ 21.3/ 21.0/ 20.5/ 19.6/ 18.7/ 17.7/ 17.0/ 16.2/ 15.5/

So the above table are the forecast flood heights for each hour in the future.
This is what is shown on the graph Matt posted.

It's still not what I'd like to see,
which is an 80% and 95% confidence interval for each point on this graph.
It would be 4 additional data points per hour.
These should be generated by their simulation.
I believe the above points are the median values (50% percentile).
I want to see the 5%, 20%, 80%, and 95%.
The folks who constructed the forecast probably have these saved somewhere,
and use them to improve their model when it goes wrong.

Overall, even though their forecast at one time was possibly embarrassingly high,
I think the alarm was properly announced, and a good decision was made to close the Valley.
Hopefully their model accuracy will improve in the future, too.

I guess that if we could see their 80% confidence interval on the 23.1 forecast point,
it might be something like [5, 26].
(It's not a symmetric interval like 23.1 +/- 18).
Then we might not be as surprised when the actual value ends up being 7 or so.
Although if the interval is wide like this, it might not be very informative,
and maybe not worth reporting constantly.
For a normal non-flood point only a few hours in the future,
an 80% confidence interval might be something like [2.5, 3.5]
(this would work as a symmetric interval 3 +/- 0.5 ).

Note: there is also an archive file from 1/4 8:55am where the forecast
was 23.7 feet, 104 hours in the future.
Ed Hartouni

Trad climber
Livermore, CA
Jan 11, 2017 - 09:31am PT
the information that generates the "Probability" graphs exists somewhere, but it might not be publicly available on the web... no one has ever asked them for it, I'm sure...

I also don't think they use confidence intervals, you can look at their publication page and read a number of descriptions on how they determine the uncertainties in the forecasts. A Bayesian method for determining those CIs would probably be an interesting research project...

While Ed B. had the luxury of not providing a prediction based uncertain data, the guys and gals at NOAA have to provide forecasts for all the river systems in the weather event region. That includes stuff way beyond Pohono Bridge... on top of the public forecasts, I'm sure they are available for consultation to the organizations responsible for making emergency decisions in the various effected regions on what the uncertainties are vis-a-vis their forecasts.

But then, "Monday morning weather forecasting" seems to inevitable....
EdBannister

Mountain climber
13,000 feet
Jan 11, 2017 - 09:57am PT
Ed Hartouni
Sir, If you look at Saturday morning, I said it then .
And on Monday my posture was not I told you so, I responded.

You guys are looking at stage, or river height as if it were volume of discharge.
Saturday morning the prediction was about 23,000 cfs reality was 10,000.
The error was not slightly less than double the real number
It was significantly more.

Bottom line
There are some, no matter what the degree of inaccuracy,
who are not willing to admit an error.
Ed Hartouni

Trad climber
Livermore, CA
Jan 11, 2017 - 10:20am PT
you wrote:

yes i said i was concerned about Monday, and i was wrong to have a concern.
But it was a concern about a threat, i assigned no number, made no prediction for Monday.


NOAH Predicted discharge was originally about 23,000 cfs
actual peak discharge was about 10,000 cfs

Do you look at the fact that the estimate was 230% of reality?

Is there some percent error amount at which you will say they were wrong?
To me, a more than double inaccuracy, is inaccurate.


Yes, early warning was good, and we all hope for the safety and well being for all.

But will the people on the ground take the next number they are given seriously??
Probably not, I did not this time, and i was correct not to do so.

I looked at weather maps and radar and estimated less that 17 feet when the estimate was 23.1 feet.
You can't undo that.


the "estimate" was a running estimate changing in time both when it was going to happen and the river stage (and flow, etc.) the estimate was not a one time thing, and we that had the luxury to look every once and a while missed all the intermediate updates...

given that this was an event happening with uncertainty in realtime, I wonder what level of accuracy you'd expect, or more importantly, how you would define "accuracy" in this particular situation.

further, NOAA was doing this throughout the western watershed as the storm moved through the entire area... with many factors changing through out that time.

They aren't "undoing" anything, they take every storm and go back and crunch the numbers to help modify their forecast methodology.

Can you point to an "error"? I'm sure they would be happy to hear from you if you could.

You might also review the idea of variability, and uncertainty quantification, and the concepts of accuracy and precision.
micronut

Trad climber
Fresno/Clovis, ca
Jan 11, 2017 - 10:29am PT
Big thanks to Ed and Clint for ruining this thread by turning it into a scientific discussion way over my head. I was hoping for a "Yeah she's gunna flood! Run for the hills!" style thread but this thing has degenerated into a bunch of facts, tables, methodologies and statistical rationale way over my pay grade. This thread needs more flood photos please!

WBraun

climber
Jan 11, 2017 - 10:34am PT
There we go ,,,, now we're talkin :-)

And by the way, those predictions prevented the chaos that ensued during the 97 flood by the park planing preventative measures before the SHTF this time ......

Good job NOAA and all you scientists ......
EdBannister

Mountain climber
13,000 feet
Jan 11, 2017 - 10:34am PT
Oh no Ed Hartouni, I was not saying you made an error.

NOAH made an error of 130%

WBraun

climber
Jan 11, 2017 - 10:38am PT
EdBannister

The error was based on temperatures being higher then they became above 9000 feet.

During 97 flood, it rained at much higher altitudes.

EdBannister

Mountain climber
13,000 feet
Jan 11, 2017 - 10:47am PT
Understood Werner,
I appreciate that NOAH did give a warning, and that Park Employees and all personnel worked in tough conditions to evacuate visitors and assure safety.


I don't have a beef, but i do recognize if you remove the emotionalism, and look at the prediction versus the result, there are some things to learn about the accuracy of the model.


If no one admits that, there will be no learning for next time.


As to Ed Hartouni references to Monday Morning Quarterbacking:
On Wednesday Jan 4, 9:52 pm when the model said 23.1 feet, i said less than 17 feet.. I went on record 4 days before, i don't recall anyone else's number before the fact... so that would take me off a list you might rightly be on.

WBraun

climber
Jan 11, 2017 - 11:02am PT
but i do recognize if you remove the emotionalism

When I first saw the 23 feet prediction I thought ..... OH SH!T !!! we're all gonna die now :-)

The original 23 foot prediction before the start of the storm series was probably just based on the 97 epic?

Then they started adjusting their predictions as their real time data was updating and everyone was watching that with laser eyeballs .....

cat t.

climber
california
Jan 11, 2017 - 11:02am PT
If no one admits that, there will be no learning for next time.

This is exactly what scientists are doing all the time: making a model, getting real world data that proves the model is incorrect in some way and modifying the model to accommodate that new information. Why the heck do you think that the scientists at NOAA are refusing to acknowledge new data? They were getting new data and modifying their predictions during the storm--they were doing exactly what you are asking for.

Over time they will get both 1) better data and 2) a better model. I think they're doing an awesome job.
EdBannister

Mountain climber
13,000 feet
Jan 11, 2017 - 11:06am PT
Yes Cat, that is science.

i just amaze at "an individual" who will get mad at me, rather than admit there is more to learn.

and sorry, i don't think the original estimate was very good.

Dingus mistakenly said NOAH's prior 60% inaccuracy was from before satellites and radar.. not true.,
and, they were also 60% inaccurate, again, last week.
Edit: correction last week they were only 57% incorrect:
23,000 forecast 10,000 reality. 57% error

All i was suggesting last wednesday, was taking the 23.1' prediction with a grain of salt...


Science, is not smarter that what it claims to study... when the results do not match the "science" it is not the results that are incorrect.




rbolton

Social climber
The home for...
Jan 11, 2017 - 11:28am PT
Is it just me or does anyone else find Ed Hartouni getting lectured on probability models and science kind of funny?
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Jan 11, 2017 - 11:30am PT
NOAH predicted the flood even before science existed!! sorry couldn't resist ;-)

EdBannister

Mountain climber
13,000 feet
Jan 11, 2017 - 11:32am PT
Tradster!!!

you are right!

I will sign off here on that note, and go post a photo...


WBraun

climber
Jan 11, 2017 - 12:44pm PT
Your prediction of 17 feet, in the beginning, was way more accurate for sure with the data of how high it will rain .......
aspendougy

Trad climber
Los Angeles, CA
Jan 11, 2017 - 02:45pm PT
NOAH or any other agency for that matter, would much rather overstate the threat and have more people flee, than understate it and have one person die as a result. For safety's sake, it is their duty to give a worst case scenario, then if their predictions are off, they get criticized, but everyone is still alive. All in all, they did a good job; the mathematics and the level of uncertainty is huge with these big weather systems.
toejahm

Trad climber
Chatsworth, CA
Jan 11, 2017 - 02:49pm PT
W Braun
What elevation did the snow line end up at this time? I lived in Wawona during the 97 flood. I can attest it was quite an event. I have photos of the swinging bridge just before the tree hit it and the aftermath. I will search tonight to see if I can find the photos. I know they're not digital, but should be worth finding.

peace,
Kenny

p.s. For those who don't know that was the year of extremes: It brought the 36" Sierra cement storm that knocked down so many trees that I believe we were cut off for a good week and also the Mono wind storm that leveled Norman May's home (RIP Norm) along with countless other homes. Norm did survive the storm, but the blue goose didn't.
tuolumne_tradster

Trad climber
Leading Edge of North American Plate
Jan 11, 2017 - 04:41pm PT
some interesting info, plots, photos, videos, etc on the #caflood twitter feed...

https://twitter.com/hashtag/caflood?src=hash
Ed Hartouni

Trad climber
Livermore, CA
Jan 11, 2017 - 10:21pm PT
what were they "wrong" about?

There are a sequence of forecasts regarding the storm,

819 AM PLT TUE JAN 03 2017
(POHC1) MAX 4.2 872 AT 4AM 01/08/17 IN 116 HRS

this one, 5 days out, says it will max at 4.2 feet at 4am in the morning of 1/8, here are the next 17 forecasts... which one is wrong? why are they different?

205 PM PLT TUE JAN 03 2017
(POHC1) MAX 5.7 1,960 AT 4AM 01/08/17 IN 110 HRS

819 AM PLT WED JAN 04 2017
(POHC1) MAX 23.7 24,700 AT 5PM 01/08/17 IN 105 HRS

855 AM PLT WED JAN 04 2017
(POHC1) MAX 23.7 24,700 AT 5PM 01/08/17 IN 104 HRS

218 PM PLT WED JAN 04 2017
(POHC1) MAX 23.1 24,400 AT 5PM 01/08/17 IN 99 HRS

841 AM PLT THU JAN 05 2017
(POHC1) MAX 15.5 15,600 AT 4PM 01/08/17 IN 79 HRS

219 PM PLT THU JAN 05 2017
(POHC1) MAX 15.9 16,200 AT 5PM 01/08/17 IN 75 HRS

834 AM PLT FRI JAN 06 2017
(POHC1) MAX 16.2 16,700 AT 5PM 01/08/17 IN 56 HRS

953 AM PLT FRI JAN 06 2017
(POHC1) MAX 16.2 16,700 AT 5PM 01/08/17 IN 55 HRS

150 PM PLT FRI JAN 06 2017
(POHC1) MAX 16.1 16,600 AT 5PM 01/08/17 IN 51 HRS

836 AM PLT SAT JAN 07 2017
(POHC1) MAX 17.6 19,000 AT 4PM 01/08/17 IN 31 HRS

158 PM PLT SAT JAN 07 2017
(POHC1) MAX 18.4 20,000 AT 4PM 01/08/17 IN 26 HRS

824 PM PLT SAT JAN 07 2017
(POHC1) MAX 19.7 21,600 AT 4PM 01/08/17 IN 20 HRS*

204 AM PLT SUN JAN 08 2017
(POHC1) MAX 15.8 16,100 AT 5PM 01/08/17 IN 15 HRS*

253 AM PLT SUN JAN 08 2017
(POHC1) MAX 15.8 16,100 AT 5PM 01/08/17 IN 14 HRS*

852 AM PLT SUN JAN 08 2017
(POHC1) MAX 12.1 9,580 AT 10PM 01/08/17 IN 13 HRS*

204 PM PLT SUN JAN 08 2017
(POHC1) MAX 11.8 9,050 AT 10PM 01/08/17 IN 8 HRS*

813 PM PLT SUN JAN 08 2017
(POHC1) MAX 12.4 9,990 AT 12AM 01/09/17 IN 4 HRS*

306 AM PLT MON JAN 09 2017
(POHC1) MAX 13.1 11,100 AT 4AM 01/09/17 IN 1 HRS*

914 AM PLT MON JAN 09 2017
(POHC1) MAX 11.7 8,960 AT CURRENT TIME *

216 PM PLT MON JAN 09 2017
(POHC1) MAX 10.0 6,600 AT CURRENT TIME
mcreel

climber
Barcelona
Jan 11, 2017 - 10:43pm PT
From that sequence, it looks like the model is fairly nonlinear, so that "small" changes in inputs can have a "big" change in outputs. That seems reasonable for a model of runoff/drainage. Stuff like this is hard to forecast accurately. Reporting confidence is important, from a scientific perspective. A forecast of 23 is not very different from one of 17, if the standard error is 5. The need to make people act to prepare to avoid extreme consequences of events that have a non-negligible probability of occurring may be a reason that reported forecasts might de-emphasize the uncertainty.
Ed Hartouni

Trad climber
Livermore, CA
Jan 11, 2017 - 10:56pm PT

here is the sequence in time, with EdBannister's prediction...

the NOAA prediction includes changes due to various weather factors... and is trying to predict how much rain will fall over some area at some time...

I ask EdBannister again, what is wrong?

Ken M

Mountain climber
Los Angeles, Ca
Jan 11, 2017 - 11:03pm PT
Dingus mistakenly said NOAH's prior 60% inaccuracy was from before satellites and radar.. not true.,
and, they were also 60% inaccurate, again, last week.

You predicted 17, and it was 12. I don't think that's such hot sh*t.

You refused to predict monday, although you were going all "Chicken-Little" on us.

Your "prediction" of 17 was just a guess. You provide NO methodology. There was NO model. What brand of darts do you use?

The accuracy of the prediction a number of days out is always going to based on information that is incomplete. Why didn't you predict 17 a month ago???

YOU changed your prediction as the time got closer. YOU DID. Does that typify you as WRONG?? I certainly wouldn't think of it that way. One alters the prediction based upon the gradually increasing quality of the information. Their prediction just hours before the event was pretty spot on.

So mr. Clairvoyant, tell us where, when, and the size of the next earthquake.
neebee

Social climber
calif/texas
Jan 11, 2017 - 11:59pm PT
hey there, say, all...

wow, i am just impressed that we can at least get warnings, these days,
as to the weather... :)

being 'such a mommy' hen, i'd prefer to get my little chicks,
out of flood range, as best i could--due to warnings, even if
they might not be perfect, :)


or, blizzards, etc...

thanks to all that share here, it is very interesting, and
such...


i liked werner's comment, about the yosemite park, here:

And by the way, those predictions prevented the chaos that ensued during the 97 flood by the park planing preventative measures before the SHTF this time ......



WHEN i lived in south texas, in the hurricane landfall-prone areas,
man oh man, we got quite a few 'never hits' that nearly did...

many stores were 'bought out' and buildings boarded up,
but-- all it takes is JUST ONE TIME NOT TO DO IT, and:

you could regret it for a long long time... :(

we just did the best we could, each storm, and then--HOPE TO GOD that it
did NOT hit... :O


we were GLAD when it was a 'off target' a bit... :)


sadly, though, for others-- they got hit...
it was a WORSE 'off target' than a 'less of a flood' situation...


it is still really really amazing though,
what we can be WARNED about, these days...


BEING in this snow area now, and BEING able to watch that ol'
DOPPLER RADAR, as the snow comes near us, man oh man,
it is AMAZING to me, :O

always makes me REMEMBER THIS:
__https://en.wikipedia.org/wiki/Schoolhouse_Blizzard__

What made the storm so deadly was the timing (during work and school hours), the suddenness, and the brief spell of warmer weather that preceded it. In addition, the very strong wind fields behind the cold front and the powdery nature of the snow reduced visibilities on the open plains to zero. People ventured from the safety of their homes to do chores, go to town, attend school, or simply enjoy the relative warmth of the day. As a result, thousands of people—including many schoolchildren—got caught in the blizzard. The death toll was 235.[3] Teachers generally kept children in their schoolrooms. Exceptions nearly always resulted in disaster.[4]


wow, guys, thanks again, for sharing all this, whether they
all match up, with each other, and all that, it is:

still amazing, :O

Travel was severely impeded in the days following



EDIT:

WOW, I JUST SAW THAT THIS WAS FROM:
january TWELFTH of all things:

http://voices.washingtonpost.com/capitalweathergang/2011/01/freak_deadly_storm_childrens_b.html

One moment the air was clear, calm, with spring-like warmth. Then, in a period of just a few minutes the sky darkened and temperatures dropped 18 degrees, and vicious winds drove tiny snow flakes (described as "ice dust") which almost instantaneously created a whiteout with visibility near zero. Blizzard conditions continued until about midnight as temperatures fell precipitously to double digits below zero with a wind chill of -40. An estimated 4-5 feet of snow had fallen, although drifting undoubtedly made accurate measurements virtually impossible.

By the next morning (Jan. 13), hundreds were killed with a high proportion of children among the storm's victims as they attempted to return home from school.



oh my:

interesting quote, from writer of article:

Laskin is also a weather geek and explains the meteorology behind the event given the available, but relatively limited sources of weather observations and analyses. This includes describing the development and progression of lows and highs, fronts, jet streams and jet streaks, which no doubt reflect the assistance in such matters when writing his book from Dr. Louis Uccellini, Director of the National Center for Environmental Prediction (NCEP) and co-author (with Paul Kocin) of Northeast Snowstorms.

To say the least, the state of the science and art of forecasting in 1888 was in the early days of development. There were no satellite observations, limited surface data and no observations aloft, let alone computers and weather models for forecasters (like Wes Junker) to peruse and come up with the best forecasts possible days in advance of possible weather threats. There were some indications of a drop in temperature and snow from surface data available to forecasters at the time, but lack of timely and reliable communications kept word from getting out before it was far too late.

We'd like to believe that advances in atmospheric science, vast system of observations, global satellite coverage, computer models, and instant communication would preclude a storm of this magnitude striking without advance notice. But surprise snowstorms remain a possibility even at short ranges to the extent the threat is communicated as a simple deterministic yes or no. With today's tools though, outright surprises can be avoided when the forecast information also includes reasonable and reliable estimates of the degree of confidence in alternative scenarios (to yes/no).

By Steve Tracton




well, night night now...

prayers for all the folks, going through stuff, right now...

and for the 'avalanche' ski patrols and
park workers in flooded areas...
all up and or down, the calif, etc, areas...
(nevada, etc, etc) ...
i-b-goB

Social climber
Wise Acres
Jan 12, 2017 - 08:59am PT
Good photos...

https://www.facebook.com/YosemiteNPS/?hc_ref=NEWSFEED&fref=nf
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Jan 12, 2017 - 09:07am PT
NutAgain!

Trad climber
South Pasadena, CA
Jan 12, 2017 - 11:32am PT
From that sequence, it looks like the model is fairly nonlinear, so that "small" changes in inputs can have a "big" change in outputs.

There you have a definition of chaos. Here is a link to a (the?) seminal paper in the field by Robert May from 1976:
"Simple Mathematical Models with Very Complicated Dynamics"
http://abel.harvard.edu/archive/118r_spring_05/docs/may.pdf


What is most remarkable to me is how you can take a simple equation from junior high math and find an INFINITE (but somehow still constrained!) level of rich varied behavior the more deeply you explore it, in terms of making infinitely small changes to a parameter and getting a dramatically different result. Perhaps it is similar to the beauty of Yosemite from the air, then a specific cliff, a specific climb, a specific pitch, a specific rock crystal, a specific attom, a specific proton, a specific quark... Mathemtically it is easier to drill down more and more deeply into a specific part of an equation in terms of what outputs are yielded for a change in input.

The part that interests me most is called "orbital analysis." You take an equation like F(x)= ax(1-x) with 'a' as some constant. Then you explore what happens when you take the answer and use it as input to the next iteration. For some values of 'a', looping through the equation will quickly blow up to infinity (or say a 100 foot flood warning). For other values of 'a', it will quickly converge to zero or another constant number and get stuck there. And then there is a value of 'a' where it "forks" to 2 different stable numbers that it toggles between. And as you change the 'a' value a tiny bit, it forks from 2, then to 4, then to 8, 16, etc... and pretty soon you just have a seemingly random cloud of possibilities that the outputs jump between. This is pictorially described in a very famous graph:


You may ave seen this more richly detailed version of a Bifurcation Diagram:


Connecting the dots back to weather... as you might imagine, the models that predict weather involve inputs of heat and moisture and pressure from thousands if not millions of point sensors, images of heat and humidity and pressure that are effectively big matrices of a bazillion data points, and they are fed into systems of equations for fluid dynamics. As you might guess, this is pretty vastly more complicated than using a single simple junior high equation.

Back to that junior high equation for a moment to graphically show HOW MUCH VARIATION is contained just in that simple expression. You have probably seen images that graphically depict what happens to an equation when you keep iterating it on itself (from stable point output to multiple stable points to chaos with seemingly infinite points but in a constrained pattern), but maybe you didn't know what you were looking at. Here are some examples:





Modern computing power has allowed everyone to see in almost inconceivably high detail the richness contained here. This is not an artists rendition of random patterns- THIS IS REAL MATHEMATICAL BEHAVIOR CONTAINED WITHIN A SINGLE SIMPLE EQUATION!!! Just hit the pause button anywhere a few minutes into this and look around for a moment before it zooms in more. It blows my mind.
[Click to View YouTube Video]

What does this mean for weather? Let's just say our weather could be predicted with that simple equation F(x) = ax (1-x), and all we had to do was get a very careful measurement of 'a'. Let's say 'a' is the temperature of a spot in the ocean somewhere. Now we get that measurement a= 7.65 degrees Celsius. Perhaps you plug that into the model and it blows up to infinity, showing a dark spot on this fractal graph. Huge flood coming. But oh wait, maybe that temperature was really a=7.648 degrees, and now the graph shows a stable result fixed at zero, so the weather report is no rain. Oh, but maybe a=7.6479 and now we get a different result. What this zoomed in graph shows you is how much the output can change as you keep zooming in, showing that for some natural systems, even a change of +/- .000000001 or more will have different results!!!! And it keeps going the deeper you look... a change of 0.000000000000000000000000000000000000001 or as far deeply as you care to look, we keep getting different results in certain critical ranges of the input variables. Perhaps the answers to life, the universe, and everything are contained herein?


So the fact that weather forecasting works at all for long range times (where you have to keep iterating the equations) is a truly remarkable human achievement. Perhaps not enough people appreciate this. Given these factors, it's pretty reasonable that weather reporters err on the side of dire forecasts if there is a risk. They just have to balance that against the risk of giving too many false-positive dire forecasts where people start ignoring them.

Edit: This might be the part where I sit down and the big kid mathematicians explain the distinction between Julia Sets and the Mandelbrot set, and fix whatever inaccuracies I stated in the process of trying to get the main point across in a simplistic way.
Clint Cummins

Trad climber
SF Bay area, CA
Jan 12, 2017 - 02:33pm PT
The variance is big because the critical event of the storm track hitting the small Merced watershed is hard to predict 100 hours in advance, when it's all far out in the Pacific.
The rain also has to arrive at a high enough temperature to have the interaction with the snowpack to yield the big flood like 1997.
The effect is nonlinear but bounded.
A lot like a drive-by shooting - if the bullet hits a wall, no big deal, but if it hits you in the head, that's often catastrophic.

It's not an unstable / chaotic interaction like x(t+1) = a*(1 - x(t)) .
It doesn't have a negative self feedback like that.
It has a small positive feedback, i.e. more runoff at time t yields more slightly more runoff at t+1 due to snow melted by the runoff.
Radish

Trad climber
SeKi, California
Jan 12, 2017 - 02:38pm PT
Thought this pic would be relative.
Clint Cummins

Trad climber
SF Bay area, CA
Jan 12, 2017 - 02:43pm PT
To be fair to Ed B, he did not forecast a point value of 17;
he said "personal prediction, not over 17 feet".
So he was right.
Ed H's graph does show that the NOAA model was heading in the direction of 17 and lower when Ed B discussed 17.
IntheFog

climber
Mostly the next place
Jan 12, 2017 - 03:45pm PT
To follow up on Clint's (and healyje's) point, that these storms are coming in from the ocean creates a bunch of problems for the models. Maybe the biggest problem is that there's much less data about conditions in the eastern Pacific. This makes it hard to predict the storm track precisely.

The reason is simple. In the jargon of forecasting, the sparser the data, the lower the resolution of the model. Lower resolution means the model isn't as precise about everything from the path of the storm to its speed to the freezing level. Any of these can make a big difference in the accuracy of the forecast at a particular point, such as the Valley.

This week's big snow in Portland shows how badly the lower resolution can screw up a forecast. The snow storm that hit Portland was part of a low pressure system centered in southern Oregon. Once the low hit land, it moved much more slowly than predicted. This made the showers over Portland move more slowly. Voila: Snowpocalypse!

The models missed the big dump because the low's speed depended on conditions in the ocean. In this case, the models needed more data to distinguish between a low that would move slowly and one would move quickly.

There's a nice discussion of "The Challenge of Pacific Northwest Weather Prediction" in Chapter 11 of Cliff Mass' "Pacific Northwest Weather." Much of what he says applies to northern California as well.
SteveW

Trad climber
The state of confusion
Jan 12, 2017 - 06:40pm PT

Tagging along with the tradster up above. . .

"NOAH, HOW LONG CAN YOU TREAD WATER?"
healyje

Trad climber
Portland, Oregon
Jan 12, 2017 - 06:49pm PT
Also keep in mind that we've only been collecting data on and attempting to model atmospheric rivers for a relatively short time.
IntheFog

climber
Mostly the next place
Jan 12, 2017 - 07:41pm PT
^^^^^
The lack of historical data means we don't have a lot of data for estimating parameters/calibrating the model, which means the the predictions will be off.

In other words: The lack of data affects what we know about both the structure of the model and the initial conditions for any particular day.

A true double whammy.

Add in that these systems come ashore in the coast ranges, where topography influences everything from wind speed and direction to moisture content, and you have a lot more whammies!

It's a wonder these models get anything right.
Majid_S

Mountain climber
Karkoekstan
Jan 12, 2017 - 09:51pm PT
Downtown San Jose main creek had easily 10 feet of water. Never seen it so high. probably homeless tents got washed out to bay and bodies will show up in Alviso
Ed Hartouni

Trad climber
Livermore, CA
Jan 13, 2017 - 01:18am PT
for those interested in pursuing the issues having to do with the uncertainty in the forecasts, the page to look at is here:

http://www.cnrfc.noaa.gov/ahps.php

especially follow the links:

http://www.cnrfc.noaa.gov/ensemble_theory.php
http://www.cnrfc.noaa.gov/esp_trace_analysis.php

which will give you an idea of what is being calculated.

For instance, I was able to make the plot forecasting the Pohono Bridge river flow from today through the end of the month:


but you can also make this plot:
this provides the estimate range for the forecast.

Seems to be a storm coming in on the19th-21st...

You can see the archived sequence of the forecast vs. measurement here:
http://www.cnrfc.noaa.gov/formHistGraphRVF_loop.php?id=POHC1&loopno=00

the sequence of plots:




shows that the precipitation input to the models at the peak fell below the actual precipitation. I would have been interesting to see the "expected value" plot for that time period next time (later this week).
healyje

Trad climber
Portland, Oregon
Jan 13, 2017 - 01:57am PT
Forecasts for the rest of the month sound like they generally revolve around a stronger polar vortex keeping arctic air from crossing very far south of the Canadian border, but they also voice a lot of uncertainty around exactly how strong or weak it will actually turn out to be. It's a tough game.
WBraun

climber
Jan 13, 2017 - 07:49am PT
Merry said at the time all the projected predictions were made the river will hit 13 feet.

She was only 3 inches off .......
rincon

climber
Coarsegold
Jan 14, 2017 - 08:05am PT
I put a 5 gallon bucket out before all the rain. It has 12 inches of water in it now!
Reilly

Mountain climber
The Other Monrovia- CA
Jan 14, 2017 - 08:14am PT
My bucket has 6" just this week here in Sin City. It is so much more scientific than my old weather rock.
Clint Cummins

Trad climber
SF Bay area, CA
Jan 14, 2017 - 12:06pm PT
Nice plots, Ed.
Especially that first one.
WBraun

climber
Feb 8, 2017 - 02:39pm PT
Oh oh .... 2 inches to flood stage today on Feb 8 2017

EdBannister

Mountain climber
13,000 feet
Feb 8, 2017 - 02:47pm PT
returning with a new event.

Werner, that is fake water out there! the model says only 9 .5 feet, and that tomorrow!!!


or maybe it is real water and the statisticians who do not acknowledge reality, or previous error, have a chance to revise their emotions and look at results.

last time the prediction was 58% inaccurate. but despite outcome, some still maintain they were correct, exactly why i said no to the NOAA recruiter.
EdBannister

Mountain climber
13,000 feet
Feb 8, 2017 - 03:24pm PT
Stage is 10.00 feet at 15:00 wednesday afternoon
rick sumner

Trad climber
reno, nevada/ wasilla alaska
Feb 8, 2017 - 03:25pm PT
Ed H could debunk those numbers and what the Duck see's with his lying eyes.
Dan McDevitt

Trad climber
yosemite
Feb 8, 2017 - 03:37pm PT
gettin' pretty loud down here in el portal. around 20,000 cfs! still rising
EdBannister

Mountain climber
13,000 feet
Feb 8, 2017 - 03:41pm PT
wow, the model was so far off of reality it looked bad, so they revised the graph to better match reality, progress.

just note this is a response post facto
EdBannister

Mountain climber
13,000 feet
Feb 8, 2017 - 04:16pm PT
16:00 wednesday 8 February USGS reading at Pohono is 10.23

The model shows stage increasing at a rate of .1 foot per hour, but reality is slightly more than double that... hmm, rate of change is also 60% inaccurate, anyone see a trend?

Thanks for the pic Dan!!!
awesome power
k-man

Gym climber
SCruz
Feb 8, 2017 - 04:21pm PT
That is movin', Dan!
I wonder what the canyon over by Coup D'état looks and sounds like.
EdBannister

Mountain climber
13,000 feet
Feb 8, 2017 - 04:40pm PT
T Hocking, actually Merry was better than that, she was exactly right to guess 13 feet.
She knew it was a guess so she used two significant numbers.

To give a prediction number with three significant figures is patently delusional.
Merry guessed 13, NOAA or as i prefer to call them NOAH, said in the last event said not about 24,
they are so delusional about their computation that they predicted 23.7 as if they were precisely accurate down to a third significant figure. This alone is a disconnect with reality, but they are so invested in the computation, that they have ceased to think.

Once again, when the model, or the "what was wrong" computation says 23.7 and reality is 12.65, it is not reality that was wrong.
WBraun

climber
Feb 8, 2017 - 04:51pm PT
It's clearing up now and stopped raining.

But!!! 140 and 120 are now closed.

Only 41 is open.

This place is getting hammered ......

(Tad, ... Merry is predicting now and I have no clue to what .... LOL)
EdBannister

Mountain climber
13,000 feet
Feb 8, 2017 - 04:59pm PT
Thanks for the update! when did the rain stop?
WBraun

climber
Feb 8, 2017 - 05:05pm PT
About a half hour ago ......
Flip Flop

climber
Earth Planet, Universe
Feb 8, 2017 - 05:06pm PT

Airbnb. Right on the river. Close to town. Good fishing.
EdBannister

Mountain climber
13,000 feet
Feb 8, 2017 - 05:18pm PT
Too funny nice yurt.


Werner, Pohono 17:00 was 10.20, so no change last hour.

Not sure what the lag time for the river is...

Radar looks clear for the rest of the day.
Chaz

Trad climber
greater Boss Angeles area
Feb 8, 2017 - 05:35pm PT
Flood? Water? What are you smoking?

Don't you read the news?

"The State Water Resources Control Board ... extends the state’s emergency drought regulations"

http://www.latimes.com/local/lanow/la-me-ln-drought-emergency-regulations-20170208-story.html

It's a drought emergency. A drought emergency.

There is no water. It's a drought.
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Feb 8, 2017 - 06:01pm PT
It's cleared up and stopped, except for teeny drops now and then.
Thanks, Kevin.
EdBannister

Mountain climber
13,000 feet
Feb 8, 2017 - 07:37pm PT
19:00 pohono stage is 10.52

EdBannister

Mountain climber
13,000 feet
Feb 8, 2017 - 08:15pm PT
20:00 pohono measures 10.89

and still going up for a few hours i think

edit: it held steady until 11, glad to be wrong.

EdBannister

Mountain climber
13,000 feet
Feb 8, 2017 - 10:29pm PT
10.97, 10.95

same number at 22:00

WBraun

climber
Feb 8, 2017 - 10:31pm PT
It will go down during the night now ......
EdBannister

Mountain climber
13,000 feet
Feb 8, 2017 - 11:23pm PT
23:00 10.9 and down it goes
ß Î Ø T Ç H

Boulder climber
ne'er–do–well
Feb 8, 2017 - 11:58pm PT
[Click to View YouTube Video]
neebee

Social climber
calif/texas
Feb 9, 2017 - 02:26am PT
hey there say, werner... wow...

say, i had just seen it was a food over,
on one of the reports...
but since the rain stopped, and such, it's going
down, you said, good to know...

wow such a powerful new way for me to see yosemite,
the river and the falls... never seen it like this...

powerful stuff... from our beloved quite little area,
of lovely surroundings, ... wow...


thanks for all the updates, werner... :)


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