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Posted at 11:15 AM ET, 01/26/2010

El Niño-linked weather arrives with a vengeance

By Andrew Freedman

* Back to January: Full Forecast | Latest on late-week snow threat *


Satellite image showing one of a series of strong storms to sweep ashore the West Coast last week. Credit: NASA.

For much of the winter, residents of the drought-weary, wildfire-prone Southwest have been wondering, "what happened to the wet El Niño winter we were promised?"

El Niño, which refers to abnormally warm water in the equatorial Pacific Ocean and associated changes to atmospheric circulation, typically brings wetter-than-normal winters across the southwestern and southern United States, due to an active subtropical jet stream.

Currently, there is a moderate El Niño event in progress. Yet up until last week, the winter of 2009-2010 had featured relentlessly dry and mild weather in the Southwest, while the rest of the country plunged into the deep freeze.

Then, as if it had intended to be fashionably late all along, Western storms finally showed up, announcing their arrival with a grand entrance.

A series of four storms slammed into California and tore a path across the Southwest, into the south-central states and the eastern seaboard. The storms smashed longstanding records for lowest barometric pressure readings, spawned tornadoes in places not typically known for them -- like Ventura County, Calif. [pdf] -- and dumped enough snow on the Sierra Nevada and in Arizona to significantly ease drought conditions.

Victor Murphy, climate services manager at the National Weather Service Southern Region, said the strong west to east jet stream (about 200 mph) across much of the Pacific Ocean, along with the low latitude storm track were "classic El Niño signals."

The statistics demonstrate just how unusual the storms were, and may make you question whether "The Niño" was taking steroids during its unscheduled break.

During the storms, which lasted from Jan. 17-22, wind gusts reached 93 mph at Newport Beach, Calif., 75 mph on the midspan of the Golden Gate Bridge in San Francisco, and a whopping 101 mph in Kingman, Ariz.

Copious amounts of rain fell in parts of Central and Southern California, including 14.49 inches at Lytle Creeke in the higher elevations of San Bernardino County, 11.56 inches at Warner Springs, 6.03 inches at John Wayne Airport in Orange County, 4.1 inches in Los Angeles, and 3.3 inches in San Diego. NOAA's National Weather Service has more information on California rainfall totals.

Heavy rains also soaked Nevada, Arizona and New Mexico, with a weekly total of 1.7 inches in Las Vegas. This was .11 inches more than fell during ALL of 2009.


Radar image showing a strong squall line passing through Phoenix, Ariz., on Jan. 21. Phoenix is near the center of the image. The reds and oranges show heavy precipitation. Credit: UCAR.

A squall line not typically seen in Arizona slammed the Phoenix metro area with heavy rain and high winds on Jan. 21. A tornado was reported near Phoenix as well. As you can see from the radar image captured as the storms were nearing downtown, this was a wall of water to be reckoned with. Phoenix recorded a five-day rainfall total of 2.4 inches, which means January is now running 1.73 inches above normal. The Arizona Republic newspaper has posted photos of the flooding that ensued, particularly from the record rains of Jan. 21-22.

John Fleck, a science reporter for the Albuquerque Journal in New Mexico, sent me this dispatch about the storms:

"I was watching in awe Thursday as the Agua Fria rose. It's a "river" north of Phoenix. Normal flow this time of year is less than 10 cubic feet per second (cfs). Late Wednesday night it hit over 40,000 cfs. That's not a typo. By comparison, the Colorado River through the Grand Canyon typically carries 17,000 cfs this time of year."

Gargantuan snow totals

While rain fell at lower elevations, in the mountains the precipitation came in the form of snow -- enough to shut down D.C. for the entire year, I think.

For example, seven feet of snow fell on Mount Baldy, in Los Angeles County, Calif. A staggering 112 inches were estimated to have fallen at Kaiser Point in the Sierra Nevada Mountains. In Arizona, 70 inches of snow fell at Sunrise Mountain, and 54.2 inches were recorded in Flagstaff. Heavy snow also fell in parts of New Mexico. Compared to these snowfall totals, D.C.'s "Snowpocalypse" seems rather wimpy, doesn't it?

As reported by the always meticulous Jeff Masters of Weather Underground, many stations in the Southwest also set new all-time records for lowest barometric pressure readings on Jan. 21. In Los Angeles, the pressure fell to 29.07 inches of mercury, which broke the old record of 29.25, set in 1988. Big cities from San Diego to Salt Lake City saw their records fall as well, leading Masters to state (about the Jan. 21 event in particular), "We expect to get powerful winter storms affecting the Southwest U.S. during strong El Niño events, but yesterday's storm was truly epic in its size and intensity."

More storms are forecast for the West this week, although nothing like last week's fierce assault.

By Andrew Freedman  | January 26, 2010; 11:15 AM ET
Categories:  Capital Weather Gang, Freedman, News & Notes, Science, U.S. Weather, Winter Storms  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: Late-week snow potential grows
Next: PM Update: A flurry or two, then clearing

Comments

Dad lives in Cedar city UT and he's been getting lots of snow. SLC is still in a drought, however.

Posted by: wiredog | January 26, 2010 11:30 AM | Report abuse

You are right about Jeff Masters being meticulous. His weather blogs are great.

Posted by: Diane30 | January 26, 2010 11:59 AM | Report abuse

"Fashionably late", indeed! Nice writing.

Posted by: B2O2 | January 26, 2010 12:30 PM | Report abuse

Wonder if anyone has the precipitation total for Death Valley from this latest series of storms?

Death Valley lies in the rain shadow of Mt. Whitney and the Panamint Range, and gets less precipitation even from the El Nino winter storms. The typical average annual rainfall for Death Valley is a bit under 1.5 inches.

Posted by: Bombo47jea | January 26, 2010 2:27 PM | Report abuse

One correction to the post: El Nino is currently classified as strong, according to NOAA, not "moderate" as I had stated. Thx to Victor Murphy of NOAA for catching that.

Posted by: Andrew-CapitalWeatherGang | January 26, 2010 3:36 PM | Report abuse

Bombo47jea,
weather.com shows Death Valley, CA receiving 1.91" this month (0.35" is normal). All but 0.01" fell during 1/17-1/21. I hope that helps.

My house in Fair Oaks, CA only had to endure 4.72" this month (4.46") is normal, so no worries of replacing the roof just yet :)

Posted by: VABBQR | January 26, 2010 10:53 PM | Report abuse

One of the major signals of weather impacts of El Nino is extension of the polar jet across the Pacific to the western U.S. A dramatic illustration of this is shown here. The charts are one week averages leading up to the active weather Andrew describes the week of Jan 17-22.

The weekly means mask individual occurrences of extremely high winds. Standard radiosonde balloons measurements along the California coast, for example, recorded winds of up to 240 mph at nominal jet levels (~40K feet). Moreover the jet core extended down to about 5K feet with 200 mph winds. The intense and very deep jet was a reflection of the largess of the energy available for driving weather at the surface.



Posted by: SteveT-CapitalWeatherGang | January 27, 2010 9:12 AM | Report abuse

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