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National Weather Service - San Francisco/Monterey Bay Area - FAQ's
Winter Weather Event February 25-26

A potent and unseasonably cold storm system moved through the Bay Area February 25th and 26th bringing a mixed bag of weather to much of the region. Simply put, this system brought a one two punch to the region with a cold front first followed by record breaking cold weather with the possiblity of snow. The storm system began to impact the region on February 25th as a cold front traversed from northwest to southeast. The frontal boundary brought very heavy rain, gusty winds, small hail and storm damage to parts of the area. Interesting to note, as the front moved south through Santa Cruz County it began to stall over the mountains producing locally higher rainfall amounts resulting in mudslides and minor flooding. Behind the front, flow would quickly become northwest allowing one of the coldest air masses seen in quiet some time to move toward the Bay Area. Profiler data located north of San Francisco along the coast inidcated that snow levels were dropping rapidly behind the front. GOES Satellite sounder data indicated that 500 MB temperatures associated with the polar core were -36° C on Febrauary 25th. This was confirmed further as model guidance initialized on February 26th at 12Z with a -36° C core right over San Francisco. The million dollar question was how much precipitation would be around when the cold air and low snow levels finally moved in? As it turns out, a few showers did linger during the early morning hours of February 26th to allow for snow all the way down to sea level. However, only trace snowfall was reported around San Francisco. Therefore the last measurable snowfall in San Francisco still remains 1976. Farther south toward Monterey, light snowfall dustings were also reported. Higher peaks above approximately 2000 feet received more measurable snowfall with a few inches, which is not unusual for this time of year. The overall airmass remained rather unstable during the afternoon of February 26th which resulted in convective rain and snow showers across the region. Several weather spotters reported snow down to sea level once again, but no accumulation was noted.

 

cold front

Frontal Passage February 25th around 16Z

rainfall totals

24 Hour Rainfall Totals

model data

Initialization Panel from Feb 26 12Z - image colors 850MB temps and lines 500MB temps

Pictures

snow on car

Snow in Marina, CA

Snow on car

Snow in Carmel Valley, CA

Snow SFsnow SF

Sunset District, San Francisco , CA
Photo By Michael Cuffe

Big Sur SnowBig Sur Snow
About 3" on the ground

Big Sur Coast, CA
Photo By Kate Novoa

Local Storm Report (LSR) - Storm damage with cold front
Click here to view Google Maps Plot

 
 NWUS56 KMTR 252013
LSRMTR

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1213 PM PST FRI FEB 25 2011

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..

0650 AM DOWNBURST NE SAN FRANCISCO 37.78N 122.41W
02/25/2011 SAN FRANCISCO CA TRAINED SPOTTER

VERY HEAVY RAINFALL,.11 INCHES IN 5 MIN TIME FRAME
ACCOMPANIED BY 35 MPH WIND.

0700 AM HAIL 4 WSW BENICIA 38.05N 122.23W
02/25/2011 M0.25 INCH CONTRA COSTA CA TRAINED SPOTTER

SMALL HAIL WITH STRONG WINDS AND INTENSE RAINFALL

0810 AM HAIL 5 W CUPERTINO 37.31N 122.14W
02/25/2011 M0.25 INCH SANTA CLARA CA CO-OP OBSERVER

SMALL HAIL, WIND GUSTS TO 39MPH, 2.15 INCHES PRECIP PAST
24 HOURS. RUNNING WATER OVER TERRAIN. SKYLINE RIDGE
PRESERVE

0810 AM HEAVY RAIN 7 ESE LOS GATOS 37.20N 121.84W
02/25/2011 M0.32 INCH SANTA CLARA CA TRAINED SPOTTER

.32 INCH PER HOUR RAIN RATE WITH WIND GUSTS 20 TO 30 MPH.
ALSO SIGNIFICANT WATER RUNOFF NOTED

Record Event Report (RER) - Record Low Temperatures
 
 SXUS76 KMTR 261841 RRA
RERMTR

RECORD EVENT REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1030 AM PST SAT FEB 26 2011


THE FOLLOWING SITES SET A NEW RECORD LOW TEMPERATURE FOR THIS DATE

LOW PREVIOUS YEAR OF
SITE TEMPERATURE RECORD PREVIOUS RECORD

NAPA 27 30 1945
OAKLAND 34 38 1987
OAKLAND INTL ARPT 32 34 1962
SFO INTL ARPT 35 36 1971
SAN RAFAEL 28 32 1996

THE FOLLOWING SITES TIED PREVIOUS RECORD LOW TEMPERATURES

LOW YEAR OF
SITE TEMPERATURE PREVIOUS RECORD

SAN FRANCISCO 37 1962
MOUNTAIN VIEW 34 1962
SAN JOSE 33 1897
Min Temp
Click image for morning lows.

MMEHLE

 



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