Rain in Feet, Yards of Snow: Cali Storm Hype
UPDATE (2PM): More stats & maps added below.
A big storm is heading towards the West Coast... some say it will be the worst in 13 years (see below for more info on past storms). California will take the brunt of the heavy rain from the biggest storm Friday into Saturday, and flooding is a huge concern. In an Associated Press article quoting AccuWeather.com, the author points out that "Homeowners still struggling to rebuild their lives after last fall's wildfires are preparing for downpours that could bring more than a foot of rain to some mudslide-prone mountain canyons." Here are some of the predictions for maximum rainfall, snowfall, and winds:
Ken Clark (PREMIUM | PRO): 15 Inches of Rain, 84" (7 Feet) of snow
Paul Yeager (PREMIUM | PRO): 10 Inches of Rain, 120" (10 Feet) of snow, 100+ mph winds
NWS: > 6 FEET OF SNOW, Winds >75 mph
MODELS (See Below):
NMM & WRF Models: >10 inches of rain
NWS QPF: >8.5" of Rain (Day2+Day3)
WAVE MODEL: 36-Foot Waves
GFS, NAM: <28.40" Pressure (Category 3 Hurricane)
The models are showing incredible amounts, so far off the chart I can't even discern what the predicted amounts are. The NMM shows rainfall amounts over 10 inches, and a large area of more than two feet of snow, as does the high-resolution WRF model (rain shown below, snow here, and it only goes out to Friday night!) Our official forecast shows a wide area of 3-4 inches of rain and over 18 inches of snow, but doesn't get any more specific than that.
WRF RAINFALL THROUGH FRIDAY NIGHT (SUPER-HUGE MAPS:N. CALI,S. CALI)
As to pressure, both the NMM and GFS are predicting a sub-28.40" low pressure system off the Northwest coast, which is the pressure equivalent of a Category 3 hurricane.
The WaveWatch model predicts a large area of waves topping 36 feet offshore, with 30-foot breakers pounding the coast.
So how long has it been since we have seen such a strong storm? Is the hype warranted?It depends, of course, on how you define "strong" or "worse" - for my definition I'll talk about the Greatest Hits on the West Coast from a series of storms that span no longer than one week. Peoples' weather memories are short, so I looked back at my own blog to find out the last big storm in California. It was only two years ago today that a superstorm (or series of powerful storms) dropped 109" of snow, 10.7" of rain, and 90 mph winds on the state. I asked Paul Yeager how he thought this storm would compare to that one. He says he thinks that it will be even stronger, based on the upper level dynamics being better this time around (he points out that the 500mb low pressure is much stronger in 2008 vs. 2006). The current storm is also pulling in moisture from across the entire Pacific Basin (look at the night before last's sat shot below).
So if it's worse, how far back do we go to find a storm of similar strength? Ken Clark says that "The strongest series of storms since the record setting 2004-2005 winter rainfall season is heading to Southern California." The NWS in Los Angeles agrees, saying "GREAT DYNAMICS...DEEP MOISTURE AND FAVORABLE JET ORIENTATION WILL CREATE A HEAVY RAIN ENVIRONMENT NOT SEEN HERE SINCE 2005."
But the NWS in San Francisco said this morning: "THESE SYSTEMS WILL BE SIMILAR TO THE DEC 11-12 1995 STORMS WHICH BOUGHT VERY HEAVY RAINS AND WINDS WELL IN EXCESS OF HURRICANE FORCE ACROSS THE SAN FRANCISCO BAY AREA."
This storm, according to Chris Burt [JessePedia], Author of "Extreme Weather" , caused a pressure reading of 28.53" at Astoria, Oregon and set an all-time record low pressure reading at Seattle (28.65"). A 103-mph gust was recorded in the San Francisco Bay. More than 15 inches of rain was recorded north of San Francisco (look on pp. 236-237 of his book for more details).
If it beats that storm, then we're probably looking back to the "Big Blow of 1962" which is also detailed on p. 236 in Chris' book.
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