000
FXUS66 KMTR 111303
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
600 AM PDT SAT OCT 11 2008
.DISCUSSION...AS OF 5:15 AM PDT SATURDAY...COLD CONDITIONS THE NEXT
COUPLE OF NIGHTS.
IMPRESSIVE TROUGH JUST TO OUR EAST WILL SLOWLY PROGRESS TO THE FOUR
CORNERS AREA OVER THE NEXT SEVERAL DAYS. THIS WILL HELP TO DECREASE
WIND SPEEDS ALOFT. AT THE SAME TIME THE ROBUST NORTHERLY GRADIENT OF
AROUND 7 MB THAT HAS BEEN ACROSS OUR AREA WILL BEGIN TO DIMINISH.
THESE TWO FACTORS WILL CAUSE WIND SPEEDS TO SLOWLY DIMINISH THROUGH
THE WEEKEND.
LOTS TO CONSIDER FOR THE FORECAST PACKAGE THIS MORNING. THE FIRST
CONCERN IS WITH THE WINDS. WITH FEW EXCEPTIONS LOWER ELEVATION
LOCATIONS HAVE NOT BEEN GUSTING MUCH OVER 25 MPH THIS MORNING SO
THE WIND ADVISORY WAS CANCELLED FOR THOSE AREAS. FOR HIGHER
ELEVATION LOCATIONS...THE EARLY INCLINATION WAS TO ALSO CANCEL IT
HOWEVER A FINAL GLANCE AT THE OBS SHOWED LOS VAQUEROS JUMPING BACK
TO OVER 50 MPH. SO THE WIND ADVISORY FOR HIGHER ELEVATION SPOTS WAS
ALLOWED TO CONTINUE UNTIL 11 AM. IT IS NOT CLEAR WHEN THE STRONG
GUSTS WILL FINALLY SHUT OFF TODAY. THE WRF SUGGESTS THAT THERE WILL
BE A CHANCE FOR GUSTS OFF AND ON DURING THE DAY ALTHOUGH IT KEEPS
THEM UNDER ADVISORY LEVELS. UNFORTUNATELY...THIS IS ONE OF THOSE
CASES WHERE THE MORNING CREW WILL HAVE TO LOOK AT THE OBS UP TO 11
BEFORE BEING ABLE TO MAKE THE CALL. THERE IS A DEFINITE CHANCE IT
WILL NEED TO BE EXTENDED THROUGH THE AFTERNOON.
THE NEXT CONCERN LIES WITH THE CHANCE OF FROST FOR SUNDAY AND
MONDAY MORNING. GUIDANCE CONTINUES TO SHOW LOWER TO MID 30S FOR A
CHUNK OF THE NORTH BAY VALLEYS ALONG WITH COOL WEATHER OVER THE
SALINAS AND HOLLISTER VALLEYS. THE BIGGEST QUESTION MARK WITH THIS
IS THE WINDS. IF THE WINDS GO UNDER 5 MPH PLACES THAT AREA
SHELTERED SHOULD DROP AT LEAST DOWN TO 35. THERE WILL BE PLENTY OF
COOL AIR IN PLACE ALONG WITH CLEAR SKIES SO CALM CONDITIONS WILL
HELP TO PUSH THEM EVEN LOWER. ALTHOUGH A FROST ADVISORY WAS ISSUED
FOR THREE DIFFERENT ZONES THE MOST LIKELY TARGETS ARE THE SOUTHERN
SALINAS VALLEY ALONG WITH PLACES NEAR THE NAPA COUNTY AIRPORT. WE
WILL FACE ANOTHER ROUND OF PATCHY FROST ON MONDAY MORNING FOR THE
SAME SPOTS ALTHOUGH ENOUGH WARMING IS EXPECTED WHICH SHOULD REDUCE
THE COVERAGE JUST A BIT. ON A SIDE NOTE...IF THE WINDS BECOME CALM
OVER THE SOUTHERN SALINAS VALLEY THE FROST WILL BE FAIRLY
WIDESPREAD. AT THIS TIME TEMPERATURES ARE NOT FORECAST TO DROP INTO
THE 20S ANYWHERE IN OUR CWA.
NICE WEATHER APPEARS TO BE ON TAP NEXT WEEK FOR THE ENTIRE DISTRICT
WITH THE STORM TRACK FORECAST TO STAY WELL TO OUR NORTH. COASTAL LOW
CLOUDS WILL START TO RETURN TUESDAY NIGHT HOWEVER THE ONSHORE
GRADIENT SHOULD STAY VERY WEAK WHILE THE NORTHERLY GRADIENT STAYS
ABOVE 3 MB. THIS SHOULD BE ENOUGH TO GREATLY LIMIT THE CLOUDS FROM
MAKING IT VERY FAR INLAND. COASTAL COMMUNITIES SHOULD SEE THE LIMITED
CLOUDS THAT DO MAKE IT TO THE COAST BURN OFF BY MID-MORNING. THE
MODELS DO BRING A WEAK STORM INTO FAR NORTHERN CALIFORNIA BY THE END
OF THE WEEK. THE ONLY IMPACT WE WILL FEEL FROM THIS IS FEWER CLOUDS
ALONG THE COAST.
&&
.AVIATION...AS OF 5:15 AM PDT SATURDAY...PLENTY OF DRY AIR AROUND
PROVIDING A CONTINUATION OF VFR ACROSS THE AREA THIS MORNING. VFR
IS FORECAST 12Z-12Z. NORTH TO NORTHWEST SURFACE WINDS ARE FORECAST
TODAY AND TONIGHT.
&&
.FIRE WEATHER...AS OF 6:00 AM PDT SATURDAY...RED FLAG WARNING IN
EFFECT THROUGH THE AFTERNOON FOR ALL LOCATIONS AND THROUGH SUNDAY
AFTERNOON FOR OUR HIGHER ELEVATIONS. NORTHERLY WINDS WITH GUSTS TO 30
MPH ARE POSSIBLE IN ALL LOCATIONS THROUGH THIS AFTERNOON WHILE GUSTS
TO 50 MPH ARE EXPECTED TO CONTINUE OVER THE HIGHER ELEVATION AREAS.
SURFACE OBSERVATIONS THIS MORNING ALSO CONFIRM THE HIGHER SPEED WITH
LOS VAQUEROS GUSTING TO OVER 50 MPH. CONDITIONS IN THE LOW LYING
AREAS WILL START TO IMPROVE BY THIS EVENING AS THE SURFACE PRESSURE
GRADIENT DIMINISHES AND WINDS START TO SUBSIDE. FOR HIGHER
ELEVATION LOCATIONS...WINDS WILL TAKE LONGER TO SUBSIDE DUE TO A
VERY STRONG STORM SYSTEM ALOFT STILL JUST TO OUR EAST. AS IT MOVES
CLOSER TO THE FOUR CORNERS AREA...WINDS WILL START TO DECREASE FOR
ALL AREAS. HUMIDITY RECOVERIES WILL MOSTLY BE 40 TO 60%
OVER THE HIGHER ELEVATION SPOTS ALTHOUGH SOME LOCAL AREAS MAY ONLY
RECOVER INTO THE MID 30S. LOOK FOR WARMER AND DRIER WEATHER FOR
MOST OF NEXT WEEK ALTHOUGH WINDS SHOULD BE LESS.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TDY...SCA...ALL COASTAL WATERS.
WIND ADVISORY...NORTH AND EAST BAY HILLS.
RED FLAG WARNING THROUGH 6 PM FOR LOWER ELEVATIONS
.TDY THROUGH SUNDAY...RED FLAG WARNING FOR ALL HIGHER
ELEVATIONS.
$$
PUBLIC FORECAST: BELL
AVIATION/MARINE: CANEPA
FIRE WEATHER: BELL
NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO
