Atmospheric River deluges California and the Southwest

By: Dr. Jeff Masters , 3:25 PM GMT on December 22, 2010

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An “Atmospheric River” of extremely moist air continues to affect the Southwest U.S. today, and flooding rains of 1 – 2” with isolated amounts of 2 – 4” can be expected across Southern California, western and central Arizona, southeastern Nevada, and southwestern Utah. The heaviest rains will fall over the coastal mountains south of Los Angeles. The storm began on Friday night, and has brought some rather remarkable rains and snows to the Southwest. Crestline, California, in the mountains just east of Los Angeles, has received 20.05” of rain since Friday. The Sierra Mountains near Sequoia National Park received an astonishing 17 feet of snow at Pescoes since Friday night. Other heavy snow amounts from the storm include 6.4' at Heavenly near Lake Tahoe, 6.5' in Crested Butte, Colorado, and 9 – 13.5' in Mammoth in the Sierras. Some other rainfall amounts from NOAA's latest Storm Summary:

...ARIZONA...
Iron Spring 11.14"
Black Rock 9.23"
Kingman 3.86"
Grand Canyon West 3.15"

...CALIFORNIA...
Crestline 20.05"
Nature Point 18.60"
Tanback 16.94"
Mammoth Lakes 12.82"
Santa Barbara 12.39"
Los Angeles-USC 6.66"
San Diego 4.22"
San Francisco Airport 2.44"

...NEVADA...
Mount Charleston 12.66"
Las Vegas, 24 miles WNW 8.99"
Reno 2.59"

...UTAH...
Gutz Peak 15.90"
Little Grassy 15.10"
Zion National Park 6.76"


Figure 1. The total amount of rainfall one could get if all the moisture in the air were condensed and fell out as rain is called the Total Precipitable Water (TPW). Here, TPW values from microwave satellite measurements are plotted, and show a plume of very moist air connecting the subtropics near Hawaii with Southern California. TPW vales in excess of 20 mm (about 0.8 inches, blue and warmer colors) are often associated with heavy rainfall events capable of causing flooding. Image credit: University of Wisconsin CIMSS.

“Atmospheric Rivers” was a term coined in the 1990s to describe plumes of moisture that ride up out of the subtropics into the mid-latitudes along the axis of a cold front. Traditional water vapor satellite imagery does not show these plumes very well, and it was only when microwave satellite imagery from polar orbiting satellites became available in the late 1990s that the full importance of these Atmospheric Rivers came to be revealed. Atmospheric Rivers account for a significant portion of California's cold season rainfall and snowfall, and an entire session was devoted to them at last week's American Geophysical Union (AGU) meeting in San Francisco, the world's largest Earth Science meeting.

Jeff Masters

High water/flooding (meto234)
The Virgin and Santa Clara rivers are topping out at flood stage at St. George, Utah. Been raining for 3 days and more on the way.
High water/flooding
Desert Rainbow (multex)
desert rainbow
Desert Rainbow
None Shall Pass (DancinPants)
That right there between me and the guy on the far side is the road....and the only one that, as far as I'm aware leads out of Pamo Valley. So he might be stuck there. I drove across there just yesterday!
None Shall Pass

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Quoting HurricaneSwirl:
Aww, TWC took away my snow chances both at day and night :( The rest of the sites aren't looking so good either. Not just my city either. Weird cause according to the special advisory I'm forecast to get an inch of accumulation, but no sites even forecast the temp to get low enough to snow..


It doesn't necessarily have to be 32F at the surface to snow. As long as the low- to mid-level atmospheric temperatures are at or below freezing, and there is sufficient moisture from 850 mb upward, snow can fall when the temperature is above freezing.

Like JG said, I think it's more to do with the fact that the low appears to be weaker in the model fields at this time.
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Quoting TampaFLUSA:
I don't see the record lows. I think you have the wrong map.


Its the right map.. Its the yellow highlighted ones are the very artic plunge back in 1989.. Just saying!
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Quoting FLPandhandleJG:


Where u at now?

b/c I think since the L is becoming weaker on some models.. That some weather services are pushing back some predictions.. Plus it could go back and forth into tomorrow morning and into tomorrow night if the L is def showing signs of development like the models were pin pointed to be.. We shall see soon..


Macon, GA.

I want to see the 0Z Euro as soon as possible so I can know if it follows on the "weaker" "trend" but I'm not gonna stay up for it.
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Quoting TampaFLUSA:
I don't see the record lows. I think you have the wrong map.


No, they're there.
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Quoting HurricaneSwirl:
Aww, TWC took away my snow chances both at day and night :( The rest of the sites aren't looking so good either. Not just my city either. Weird cause according to the special advisory I'm forecast to get an inch of accumulation, but no sites even forecast the temp to get low enough to snow..


Where u at now?

b/c I think since the L is becoming weaker on some models.. That some weather services are pushing back some predictions.. Plus it could go back and forth into tomorrow morning and into tomorrow night if the L is def showing signs of development like the models were pin pointed to be.. We shall see soon..
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Never mind.
Member Since: June 21, 2007 Posts: 10 Comments: 1657
Aww, TWC took away my snow chances both at day and night :( The rest of the sites aren't looking so good either. Not just my city either. Weird cause according to the special advisory I'm forecast to get an inch of accumulation, but no sites even forecast the temp to get low enough to snow..
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here's the Nam model..
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Quoting captainhunter:
Just wanted to jump in out of lurkspace to wish everyone a Happy Holiday Season. Taz, Pottery. Baha, Press, and everyone...Hope you all have a great New Year.

Thanks, Hunter!
May the breezes stay in your favourite quarter, all the rest of your days!
Have a Wonderful Christmas.
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Noting the Lows in La. in 1989 during the Arctic True Blue Norther




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Latest for West Palm Beach

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Just wanted to jump in out of lurkspace to wish everyone a Happy Holiday Season. Taz, Pottery. Baha, Press, and everyone...Hope you all have a great New Year.
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596
fxus64 klix 230224
afdlix


Area forecast discussion
National Weather Service New Orleans la
824 PM CST Wednesday Dec 22 2010


Update...


Sounding discussion...
no problems with the flight this evening. Overall a pretty stable
sounding. Relatively moist lower part of the atmosphere...precipitable
water value around 0.80 inches with a lifted index of 4.8. Clear
skies can be expected due to relatively dry middle and upper levels.
Winds are light and out of the north near the surface...then
shifting to out of the west in the upper levels of the atmosphere.


&&


Previous discussion... /issued 321 PM CST Wednesday Dec 22 2010/


Synopsis...
cold front working its way southeastward through the area...and
should clear all but lower Plaquemines Parish in next couple of
hours. Wind shift and drier air should allow marine based fog to
depart area. Clouds should also dissipate from the north.
Temperatures reached the middle to upper 70s in most areas before the
frontal passage.


Short term...
southward extension of Canadian high pressure will dry things out
for the next 48 to 60 hours. Model soundings show a drop of about
10c over the next 24 hours...which will put high temperatures for
Thursday in the upper 50s to around 60. This fits with guidance
and going forecast. Will see 2 to 3 degrees of moderation on
Friday.


Extension of high moves east Friday night into Saturday...allowing
for a return flow of moisture. Models showing 3 separate streams
of energy moving out of The Rockies on Saturday. Beginning to see
more agreement between the models with the forecast scenario. All
3 models indicate that a surface low will develop over the
northern Gulf...passing just south of our area during the daytime
hours Saturday. Have bumped probability of precipitation up to likely across the entire
area for Saturday. Best instability will be south of the area so
thunder is not expected to be an issue. Rain amounts generally
expected to remain under one half inch. 35


Long term...
low pressure shifts well to the east Saturday night before
cranking up to what may be a significant storm for the East Coast.
The only effect this system will have on our area past Saturday is
to provide strong northerly flow from Canada. This will bring cold
and dry weather to the area. Looking at subfreezing overnight lows
for Sunday night through Tuesday night...with the coldest being
Monday night...where a hard freeze is likely north of the tidal
lakes...and a light freeze south of the lakes. Temperatures will
begin to moderate Wednesday. Until then...high temperatures will
struggle to get much past 50 0r 55. 35
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Quoting BahaHurican:
Calm down, he was joking becaue he always reports pple...

lol

I'm sure he was.
Where does Taz live, in relation to the flooding?
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Quoting MichaelSTL:


That article is dated January 19, 2006 (I think you meant this one, dated December 21, 2010).

Although there really is drought in Texas right now:


In truth, I had seen that.
But you know how the graphics sometimes dont tell the whole story.
That's Serious stuff there!
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Quoting MichaelSTL:


That article is dated January 19, 2006 (I think you meant this one, dated December 21, 2010).

Although there really is drought in Texas right now:



Thanks...

You know what they say, "dyslexics of the world untie"
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Quoting TampaFLUSA:
Calm down, he was joking because he had nice weather.
Calm down, he was joking becaue he always reports pple...

lol
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Here's an early prediction.. just heresay now.. Could change..
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Quoting pottery:

Yikes!!!
I did not realise that things were so critical there...
Is this part of a trend, over the past few years, or what?


Predicted (one of atomaggies profs)

October Warning

We were pretty bad last summer... recovered in the cool months, dry spring, July wet

Nada, nada, nada since August

This last year if they ain't drought and freeze tolerant they are dead (most survived... lost a few zone 9a types last winter)
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Whats everyone's opinion about this potential storm this weekend into monday and possibly tuesday if rides up the east coast to the Northeast.. Do y'all think it will be a mega storm, an average storm system, or just too much hype.. ?

To me i think by tomorrow morning or so we will know a lil more data on a potential storm that could get stronger.. There's a possibility though.. going back to some of the models and all see if anything changed..
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Quoting presslord:


it's OK...I've been married long enough I'm used to it...

LOL.
Selective hearing.....
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Quoting EnergyMoron:


All counties in Texas were declared a disaster area today.

Link

I am still watering some plants I planted in early August...

nada

nada

nada

40% for Friday...

Yikes!!!
I did not realise that things were so critical there...
Is this part of a trend, over the past few years, or what?
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Quoting FLPandhandleJG:


I dont think he is answering at the moment.. lol


it's OK...I've been married long enough I'm used to it...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Quoting presslord:


Howdy Taz...Merry Christmas!!!


I dont think he is answering at the moment.. lol
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Quoting Tazmanian:




you been reported


Howdy Taz...Merry Christmas!!!
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Not weather related directly, but:

Anyone in the blog has any experience with an android tablet? I'm looking to buy one like this on Ebay..... Near $100 7 inch, Android 2.1 OS
Any advice on this???

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Quoting Chicklit:
I want some rain for Christmas.


All counties in Texas were declared a disaster area today.

Link

I am still watering some plants I planted in early August...

nada

nada

nada

40% for Friday...
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Quoting pottery:

I'm trying.
Truly...
But you know, these things just slip out.....
In fact, just for information, it will probably stay really nice and warm, with gentle tropical breezes and benign showers, for the foreseeable future.

heheheheheh


always knew you were trouble ; )
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Quoting pottery:

Evening, Sunline..
You getting rain?


Mostly cloudy all day, no rain, 70's...

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Quoting Chicklit:
I want some rain for Christmas.

You can have some of mine....
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Quoting sunlinepr:
Good Evening All.....



Evening, Sunline..
You getting rain?
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I want some rain for Christmas.
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Quoting BahaHurican:
It's starting to look like we may get some rain here also, though that's the exception rather than the rule... interesting to realize that ur rainy season in "winter" occurs for the same basic reason that ours does in summer.... lol

Happy Christmas!

True!
And Happy Christmas to you and yours as well.
Hope you have a Fantastic New Year, too...
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Quoting hydrus:
oh yeah.....rubbin it in deep Pott.....The wind chill here is 20 degrees right now..

Sounds Dread to me, Hydrus!
You guys are made of Sterner Stuff than us Tropical Weeds....
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Quoting Tazmanian:




rreported

LOL,
Hello, Taz.
You underwater yet?
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Quoting Tazmanian:




rreported
Calm down, he was joking because he had nice weather.
Member Since: June 21, 2007 Posts: 10 Comments: 1657
Good Evening All.....


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Quoting presslord:


shut up

I'm trying.
Truly...
But you know, these things just slip out.....
In fact, just for information, it will probably stay really nice and warm, with gentle tropical breezes and benign showers, for the foreseeable future.

heheheheheh
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Quoting presslord:


shut up




you been reported
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350. Skyepony (Mod)
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Quoting pottery:

Enjoying the relatively cooler temps here too.
But we are getting showers, with a lot more to come this week with plenty ITCZ activity overhead and east of here.
Going to be a rainy Christmas....
It's starting to look like we may get some rain here also, though that's the exception rather than the rule... interesting to realize that ur rainy season in "winter" occurs for the same basic reason that ours does in summer.... lol

Happy Christmas!
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The HDC has updated a few of the snowfall/rainfall figures Dr. Masters gave above. Among the most glaring of the updated measurements, Crestline, CA, has now received 26.16" of rain since Friday (that figure was 20.05" this morning). Luckily, the current rain event appears to be about over,

Today was longer than yesterday, and tomorrow will be longer than today, and so on and so forth for the next six months, warming up along the way. And as if that's not good enough news, there's also this: there are only 159 days, 22 hours, and 46 minutes until the 2011 hurricane season gets underway. Nice to have something to look forward to, no?
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My last electric bill was under $90. I love the colder weather down here.
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Quoting pottery:
Got down to a frigid (LOL) 71 at 3:00 am, and peaked at a nice 77 at 11:00 am.
Must be Christmas or something....
oh yeah.....rubbin it in deep Pott.....The wind chill here is 20 degrees right now..
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Quoting JFLORIDA:

I think no matter what come jan 1st something notable will also occur.


Out of the loop on this one J...What are the models showing for the beginning of the New Year?
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Quoting pottery:

Enjoying the relatively cooler temps here too.
But we are getting showers, with a lot more to come this week with plenty ITCZ activity overhead and east of here.
Going to be a rainy Christmas....


shut up
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Got down to a frigid (LOL) 71 at 3:00 am, and peaked at a nice 77 at 11:00 am.
Must be Christmas or something....
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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