Wind Advisory 14, NWS San Francisco Bay Area, CA

000 
WWUS76 KMTR 022001
NPWMTR

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1201 PM PST SAT DEC 2 2006

CAZ510-511-022115-
/O.EXP.KMTR.WI.Y.0014.000000T0000Z-061202T2000Z/
EAST BAY INTERIOR VALLEYS-EAST BAY HILLS AND DIABLO RANGE-
1201 PM PST SAT DEC 2 2006

...WIND ADVISORY WILL EXPIRE AT NOON PST TODAY...

THE WIND ADVISORY FOR THE EAST BAY HILLS AND THE DIABLO RANGE
ABOVE 1000 FEET WILL BE ALLOWED TO EXPIRE AT NOON PST TODAY.

GUSTY EAST TO NORTHEAST WINDS WILL CONTINUE ACROSS THE AREA
THROUGH THE AFTERNOON BUT WILL BE BELOW ADVISORY CRITERIA. LOCAL
GUSTS OF 35 TO 45 MPH WILL STILL BE POSSIBLE IN FAVORED AREAS
THROUGH THE DAY.

$$

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
403 AM PST SAT DEC 2 2006

.DISCUSSION...WITH DEW PTS UP AND A LITTLE MORE WIND TO MIX THE
BOUNDARY LAYER TEMPS ARE NOT AS COOL AS THE PREVIOUS COUPLE OF
MORNINGS. THERE HAS BEEN PATCHY RADIATION FOG...ESPECIALLY IN THE
NORTH BAY NEAR SANTA ROSA.

A RIDGE OF HIGH PRESSURE CENTERED ALONG 130W HAS PUSHED THE STORM
TRACK INTO BRITISH COLUMBIA. THIS PATTERN WILL PERSIST THROUGH THE
WEEKEND WITH THE WEAK OFFSHORE FLOW GETTING STRONGER AS A 1053
ARCTIC HIGH SINKS THROUGH THE ROCKIES. TEMPS WILL BE MILD...MAINLY
IN THE 60S...GREAT WEATHER FOR OUTDOOR ACTIVITIES...OR SHOPPING.
LOOKING AHEAD...THIS COULD BE THE LAST WEEKEND IN A WHILE TO BOAST
SUCH BEAUTIFUL WEATHER.

BOTH THE EURO AND GFS ARE SIMILAR IN DEPICTING THE PATTERN UNDERGOING
A LARGE CHANGE AS THE RIDGE MOVES EAST INTO THE PLAINS STATES AND A
DEEP TROF BECOMES NEGATIVELY TILTED FROM THE GULF OF ALASKA TO 130W
WITH THE JET DIPPING SOUTH. THIS WEEK WILL BE THE TRANSITION AS THE
RIDGE STARTS TO BREAK DOWN AS SHORTWAVES RIDE OVER THE TOP. THE
IMPETUS FOR THIS CHANGE SEEMS TO BE THE MADDEN JULIEN OSCILLATION
(MJO) WHICH SEEMS TO HAVE BECOME MORE ACTIVE (INCREASED CONVECTION)
NEAR THE DATELINE ON NOV 30TH. THE IMPACTS OF THE INCREASED
CONVECTION BEING AN ENHANCEMENT OF THE SUBTROPICAL JET ALLOWING THE
WESTERLIES TO PROGRESS FURTHER EAST THAN NORMAL THUS IMPACTING
CENTRAL CALIFORNIA. FROM THE MJO CURRENT LOCATION IT SHOULD TAKE 8
TO 10 DAYS TO REACH CALIFORNIA. CDC EXPERIMENTAL ANALOG PROBABILITY
OF PRECIPITATION FORECASTS FOR THE 6-10 DAY PERIOD (DEC 6-11) SHOW A
GREATER THAN 70% CHANCE OF RAIN GREATER THAN 2.5 MM...WHEREAS CLIMO
FOR THE SAME PERIOD IS MORE THAN 20% LESS. THE 8-14 DAY EXPERIMENTAL
ANALOG FORECAST INDICATES GREATER THAN 80% CHANCE OF RAIN EXCEEDING
2.5 MM WHEREAS CLIMO IS 20-30% LESS. BOTTOM LINE IS THAT THE DISTRICT
COULD BE IN AN EXTENDED PERIOD OF WET WEATHER STARTING LATE NEXT
WEEK AND WEEKEND.

&&

.AVIATION...NOT MUCH CHANGE IN THOUGHT FROM THE AFTERNOON DISCUSSION
EXCEPT THAT NIGHTTIME COOLING HAS BROUGHT STS CLOSER TO FOG FORMATION
AT QUICKER PACE THAN ORIGINALLY THOUGHT. THE AIRMASS IS A BIT MORE
HUMID TONIGHT. CLEAR SKIES WILL ALLOW RADIATIONAL COOLING PROCESSES
TO LEAD TO PATCHY VALLEY FOG AS INDICATED IN THE PUBLIC ZONES.
ELSEWHERE THERE SHOULD BE ENOUGH MIXING FROM LIGHT OFFSHORE FLOW AND
DRAINAGE WINDS TO PREVENT FOG FROM FORMING SAT MORNING. VFR WILL
LIKELY PREVAIL AT ALL AREA TERMINALS SATURDAY.

&&

.MTR...NONE.

PUBLIC FORECAST: STROBIN
AVIATION/MARINE: W PI

NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO