000
FXUS66 KMTR 070301 AAA
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
800 PM PDT SAT SEP 6 2008
.DISCUSSION...UPDATE AS OF 8:00 PM PDT SATURDAY...HOT WEATHER
FINALLY COMES TO AN END.
EVERYTHING APPEARS TO STILL BE ON TRACK FOR COOLER TEMPERATURES
TOMORROW AND MUCH COOLER WEATHER ON MONDAY AS THE HOT DOME OF AIR
THAT HAS BEEN OVERHEAD THE PAST FEW DAYS IS DISPLACED FURTHER TO
THE SOUTHEAST. TEMPERATURES TODAY SOARED IN MANY SPOTS WITH MANY
SPOTS NEAR OR ABOVE THE CENTURY MARK. OVERALL HIGHS WILL BE
CONSIDERABLY COOLER TOMORROW WHICH WILL BE THE START OF MORE
ENJOYABLE WEATHER FOR MUCH OF NEXT WEEK. STILL LOOKS LIKE VIRTUALLY
ALL SPOTS WILL REMAIN FOG FREE TONIGHT WITH THE HIGH RESOLUTION WRF
MODEL SHOWING ONLY PATCHY CONDITIONS OVER MONTEREY BAY AND ALONG
THE COAST FROM NORTHERN MARIN COUNTY UP THROUGH MUCH OF SONOMA
COUNTY. LOOKING TOWARD THE END OF NEXT WEEK THE ECMWF STILL SHOWS A
LOW OFF THE SOUTHERN CALIFORNIA COAST HELPING TO DIRECT MONSOONAL
MOISTURE TOWARD US WHILE THE GFS OFFERS A DRAMATICALLY DIFFERENT
SOLUTION WHICH WOULD KEEP ANY SHOWER ACTIVITY WELL AWAY FROM US. AT
THIS TIME AGREE WITH THE PREVIOUS SHIFT THAT IT IS FAR TOO SOON TO
MAKE A CALL ON WHICH WAY THIS WILL PAN OUT.
.PREVIOUS DISCUSSION AS OF 1:50 PM PDT SATURDAY...CONDITIONS
EARLY THIS AFTERNOON ARE NEARLY IDENTICAL TO YESTERDAY AFTERNOON WITH
WARM TEMPERATURES AT THE COAST AND HOT TEMPS INLAND. RECORD HIGH
TEMPS ARE POSSIBLE IN A FEW SPOTS...BUT UNLIKELY IN MOST AREAS AS
RECORDS ARE GENERALLY PRETTY HIGH FOR THIS DATE.
TOMORROW STILL LOOKS TO BE THE TRANSITION DAY AS WE FINALLY BEGIN
TO COOL OFF. A WEAK UPPER LEVEL TROUGH CURRENTLY DROPPING SOUTH
ALONG THE WASHINGTON COAST IS FORECAST TO SAG INTO NORTHERN CA LATE
TONIGHT AND SUNDAY. AS IT DOES SO...THERE WILL BE SOME SLIGHT
AIRMASS COOLING. BUT MORE IMPORTANTLY FOR OUR FORECAST...THE
APPROACHING TROUGH WILL TRIGGER A RETURN TO ONSHORE FLOW.
TEMPERATURES SHOULD COOL FROM 7 TO 15 DEGREES NEAR THE COAST AND
BAYS ON SUNDAY...AND IN SOME OF THE COASTAL VALLEYS AS WELL. THE
MARINE LAYER WILL REMAIN QUITE SHALLOW THROUGH SUNDAY AND SO COOLING
IN THE HILLS AND THE VALLEYS FARTHEST INLAND WILL PROBABLY BE
LIMITED TO ONLY A FEW DEGREES.
THE BIG SUR COAST IS THE ONLY AREA THAT HAS SEEN FOG TODAY AND RECENT
SATELLITE TRENDS INDICATE THE FOG LAYER THERE IS RETREATING TO THE
SOUTH. FOG AND LOW CLOUDS WILL DEVELOP ALONG OUR ENTIRE COASTLINE
SOMETIME IN THE NEXT 24-36 HOURS...BUT PINPOINTING THE TIMING OF
THIS ISN`T EASY. THE 18Z NAM INDICATES MOST COASTAL FOG DEVELOPMENT
WILL HOLD OFF UNTIL LATE SUNDAY AFTERNOON/SUNDAY EVENING. THE HIGH
RESOLUTION WRF INDICATES PATCHY FOG DEVELOPING ON THE NORTH BAY COAST
LATE TONIGHT...AND THEN BECOMING MORE WIDESPREAD THROUGH THE DAY ON
SUNDAY. WILL FORECAST ONLY PATCHY COASTAL LOW CLOUDS AND FOG
TONIGHT...WITH MUCH MORE WIDESPREAD COVERAGE SUNDAY NIGHT INTO MONDAY
MORNING.
THE COOLING TREND WILL SPREAD FARTHER INLAND MONDAY AND TUESDAY AS
THE UPPER LEVEL TROUGH DEEPENS ALONG THE WEST COAST. BY TUESDAY...
MOST AREAS SHOULD SEE TEMPERATURES RETURN TO NEAR NORMAL. NO BIG
CHANGES ARE THEN ANTICIPATED THROUGH THE REMAINDER OF NEXT WEEK AS A
WEEK TROUGH LINGERS NEAR THE WEST COAST. BY LATE IN THE WEEK THE
MEDIUM RANGE MODELS DEVELOP A CLOSED LOW SOMEWHERE NEAR THE CENTRAL
OR SOUTHERN CA COAST. EARLIER MODEL RUNS OF BOTH THE GFS AND ECMWF
HAD INDICATED THAT CIRCULATION AROUND THIS LOW WOULD DRAW SIGNIFICANT
MID/UPPER LEVEL SUBTROPICAL MOISTURE UP OVER OUR REGION LATE IN THE
WEEK AND INTO NEXT WEEKEND. HOWEVER...THE 12Z VERSION OF BOTH MODELS
AGREE THAT NEARLY ALL MOISTURE WILL REMAIN WELL TO OUR EAST.
THEREFORE...HAVE DECIDED TO LEAVE POPS AT ZERO THROUGH THE EXTENDED.
&&
.AVIATION...AS OF 4:25 PM PDT SATURDAY...VFR CONDITIONS PREVAIL. KMRY
AND KSNS MAY SEE SOME STRATUS VERY EARLY SUNDAY MORNING BUT IT SHOULD
BE LIMITED. VFR IS EXPECTED AT ALL TERMINALS SUNDAY.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...SCA...SF BAY EVENING HOURS.
$$
PUBLIC FORECAST: DYKEMA/BELL
AVIATION/MARINE: GUDGEL/CANEPA
NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO
