FXUS66 KMTR 061752
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
1050 AM PDT SAT SEP 6 2008

UPDATED AVIATION DISCUSSION

.DISCUSSION...AS OF 9:05 AM PDT SATURDAY...NOT MUCH HAS CHANGED
SINCE YESTERDAY MORNING. TEMPERATURES AT 8 AM WERE VERY CLOSE TO
WHERE THEY WERE 24 HOURS PREVIOUS. SURFACE GRADIENTS HAVE NOT
CHANGED MUCH AND ARE MODERATE OFFSHORE FROM THE GREAT BASIN TO
THE COAST...WEAK ONSHORE FROM THE COAST TO THE CENTRAL VALLEY...WITH
A SLIGHT N-S GRADIENT DOWN THE COAST. A VERY SHALLOW MARINE LAYER
REMAINS CONFINED THE THE IMMEDIATE COAST WITH FOG BANKED UP AGAINST
THE BIG SUR COAST. THE 12Z OAK SOUNDING INDICATES THERE HAS
BEEN SLIGHT COOLING BELOW ABOUT 925 MB AND SLIGHT WARMING ABOVE THAT
LEVEL. GIVEN ALL THAT...DON'T SEE MUCH CHANGE IN HIGH TEMPERATURES
TODAY COMPARED TO YESTERDAY. THE EXCEPTION MAY BE COASTAL AREAS
WHERE SLIGHT COOLING IS LIKELY GIVEN THE GRADUAL INCREASE IN ONSHORE
GRADIENTS THAT IS EXPECTED TO OCCUR FROM THE COAST TO THE CENTRAL
VALLEY.

AFTER SEVERAL DAYS OF HEAT...COOLING RELIEF IS EXPECTED TO BEGIN ON
SUNDAY WHEN ONSHORE PICKS UP AS A WEAK SHORTWAVE TROUGH APPROACHES
FROM THE NW. TEMPS NEAR THE COAST...NEAR SF BAY...AND IN COASTAL
VALLEYS SHOULD COOL SEVERAL DEGREES ON SUNDAY. MAY NEED TO ADJUST
TEMPS IN THOSE AREAS DOWN FROM WHAT IS IN THE CURRENT FORECAST.

THE COOLING TREND WILL CONTINUE TO PRESS INLAND MONDAY AND TUESDAY
AS AN UPPER TROUGH SLOWLY DEEPENS ALONG THE WEST COAST. TEMPS WILL
RETURN TO NEAR NORMAL IN ALL AREAS BY TUESDAY. THE NEXT IMPORTANT
FORECAST ISSUE WILL BE THE POSSIBILITY OF CONVECTION LATE IN THE
FORECAST PERIOD AS CIRCULATION AROUND AN UPPER LOW OFFSHORE ADVECTS
SUBTROPICAL MOISTURE OVER THE AREA. BOTH THE ECMWF AND GFS INDICATE
AN INCREASE IN MID/UPPER LEVEL MOISTURE BEGINNING NEXT FRIDAY. WILL
CONSIDER ADDING SOME LOW POPS TO THE FORECAST FROM FRIDAY INTO NEXT
WEEKEND...ESPECIALLY OVER THE SOUTHER PORTION OF OUR DISTRICT.

&&

.AVIATION...AS OF 10:50 AM PDT SATURDAY...HIGH PRESSURE WITH
ASSOCIATED SUBSIDENCE ALOFT MAINTAINING CAVU CONDITIONS ACROSS THE
CENTRAL COAST AND S.F.BAY AREA TERMINALS. LIGHT ONSHORE PRESSURE
GRADIENTS ENHANCED BY INTENSE INTERIOR HEATING TO PUSH AFTERNOON
BREEZES AT KSFO AFT 22Z WESTERLY 18G25KTS BUT DIMINISHING AFTER 03Z
THIS EVENING. STRATUS FIELD EXPECTED TO ENHANCE ALONG THE MONTEREY
COAST AND BUILD NORTH OVERNIGHT SO HAVE INTRODUCED SOME LOW
OVERCAST AND IFR CEILINGS AROUND KMRY AND KSNS TERMINALS AFT 10Z.

&&


.MTR WATCHES/WARNINGS/ADVISORIES...
.TDA...SCA...SF BAY AFTERNOON HOURS.

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: GUDGEL


NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO

Back to Main Forecast Discussion Page