Is Al Gore at his Fisherman’s Wharf Condo? Our own Charles The Moderator sent me a query today, along with a link to this SFO Chron article about the possibility of snow down to sea level. It’s possible, and has happened before as shown by the photo below.
About an hour later, I got an email from my friend Jan Null, former lead forecaster for the NWS in SFO, who has put together a nice summary that I will share with everyone. First, the forecast: The forecast for Mount Tamalpais and other hilly areas of Marin County calls for snow:
But, for SFO City, no snow in the forecast, yet:
In his briefing, Jan Null writes:
To snow or not to snow, that is the question.
The weather pattern is certainly shaping up for a significant blast of Arctic air to invade California beginning Friday. The question being asked is whether the elements are in place for there to be snow all the way down to sea level around San Francisco Bay. The last time there was a significant covering of snow at sea level in the Bay Area was February 5, 1976.
http://ggweather.com/sf/snow.htm and http://thestormking.com/Sierra_Stories/San_Francisco_Snowstorms/san_francisco_snowstorms.html for this and other historic SF snow events..
I have extracted the surface and 500 millibar maps from that date. See
The Oakland sounding from 12z on Feb. 5, 1976 had a 500mb height of 5280m and a 1000-500 thickness of 5220m.
The current (18Z) GFS has a 500mh height of 5320 m and a thickness of 5220 m. See http://wxweb.meteostar.com/sample/sample.shtml?text=KOAK and also
The toughest part of the equation is whether the precipitation will phase with the coldest air during the coldest time of day. Any of a number of subtle changes to the airmass and its trajectory over the ocean could make dramatic differences to the eventual outcome. Stay tuned.
The NWS in SFO has issued this special weather statement:
WWUS86 KMTR 222338
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
338 PM PST TUE FEB 22 2011
338 PM PST TUE FEB 22 2011
…COLD STORM SYSTEM TO IMPACT OUR AREA STARTING ON THURSDAY…
…SNOW LEVELS EXPECTED TO DROP CLOSE TO SEA LEVEL BY FRIDAY NIGHT…
AFTER A QUIET WEATHER DAY TODAY AND WEDNESDAY…A RETURN TO COLD
WINTRY CONDITIONS ARE EXPECTED ACROSS THE SAN FRANCISCO AND
MONTEREY BAY REGION BY THURSDAY. A STRONG STORM SYSTEM CURRENTLY
IN CANADA WILL DIVE TO THE SOUTHEAST AND BE NEAR THE SAN FRANCISCO
BAY AREA FRIDAY NIGHT. AHEAD OF THE LOW…RAINFALL WILL SPREAD
ACROSS OUR AREA STARTING THURSDAY AND CONTINUING INTO FRIDAY.
RAINFALL AMOUNTS COULD EXCEED HALF AN INCH FOR CITIES WITH MORE
THAN AN INCH POSSIBLE FOR HIGHER ELEVATIONS. SNOW LEVELS WILL DROP
THROUGH THE DAY AND BE UNDER 1500 FEET FOR MOST OF SAN FRANCISCO
BAY AND BETWEEN 2000 AND 2500 FEET ON FRIDAY. SIGNIFICANT SNOW
ACCUMULATIONS WILL BE POSSIBLE FOR LOCAL MOUNTAIN RANGES. EVEN COLDER AIR WILL CONTINUE TO FILTER IN THROUGH FRIDAY NIGHT WITH SNOW LEVELS POTENTIALLY DROPPING DOWN TO SEA LEVEL.
ALTHOUGH THE STORM SYSTEM IS STILL A FEW DAYS AWAY…CONFIDENCE IS
FAIRLY HIGH THAT WE WILL SEE MUCH COLDER THAN NORMAL WEATHER AND
VERY LOW SNOW LEVELS. IT IS IMPORTANT TO NOTE THAT AT THIS TIME
THERE IS STILL SOME UNCERTAINTY WITH THE CHANCE FOR ACCUMULATING
SNOW AT VERY LOW ELEVATIONS. EVEN IF THE SNOW DOES NOT ACCUMULATE
AT SEA LEVEL…IT WILL LIKELY IMPACT LOCAL PASSES AND ANY ROADS
ABOVE THE 1000 FOOT LEVEL.
PERSONS WITH OUTDOOR ACTIVITIES AROUND SAN FRANCISCO AND MONTEREY BAY LATER THIS WEEK SHOULD PAY VERY CLOSE ATTENTION TO THE LATEST FORECASTS. REMEMBER TO ALWAYS CARRY AN EMERGENCY KIT IN YOUR CAR IN CASE YOU DO ENCOUNTER HAZARDOUS DRIVING CONDITIONS.