Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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000
FXUS66 KMTR 021125
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
425 AM PDT SUN AUG 2 2015

.SYNOPSIS...A SUBTLE COOLING TREND IS FORECAST TO CONTINUE THROUGH
TUESDAY AS ONSHORE FLOW AND THE MARINE INFLUENCE INCREASES. MODEST
WARMING IS THEN FORECAST FOR WEDNESDAY AND THURSDAY. ASIDE FROM
PATCHY COASTAL DRIZZLE AND FOG DURING THE OVERNIGHT AND EARLY
MORNING HOURS...DRY WEATHER CONDITIONS ARE EXPECTED TO PERSIST
THROUGH THE FORECAST PERIOD.

&&

.DISCUSSION...AS OF 3:10 AM PDT SUNDAY...AN UPPER LEVEL RIDGE
CONTINUES TO DOMINATE THE WESTERN CONUS WHILE A WEAK TROUGH IS
NEARLY STATIONARY OFF THE WEST COAST BETWEEN 130 AND 140W. OVER
THE NEXT FEW DAYS THE RIDGE IS FORECAST TO WEAKEN AND SHIFT EAST.
AT THE SAME TIME...WEAK IMPULSES EJECTING OUT OF THE TROUGH
OFFSHORE WILL TRACK TO THE ENE AND ACROSS NORTHERN AND CENTRAL
CALIFORNIA. THESE DEVELOPMENTS WILL RESULT IN MODEST COOLING OVER
THE NEXT THREE DAYS...WITH DAYTIME TEMPS ACROSS INLAND AREAS
FORECAST TO DROP TO AS MUCH AS TEN DEGREES BELOW NORMAL BY
TUESDAY. WIDESPREAD NIGHT AND MORNING LOW CLOUDS WILL CLEAR INLAND
BY MIDDAY EACH DAY...BUT ONLY PARTIAL AFTERNOON CLEARING IS
EXPECTED AT THE COAST.

BY MIDWEEK THE TROUGH OFFSHORE IS FORECAST TO DEEPEN AND FORM A
CUTOFF LOW OUT NEAR 140W. DOWNSTREAM FROM THIS DEEPENING TROUGH A
SHORTWAVE RIDGE WILL DEVELOP OVER CENTRAL AND SOUTHERN CALIFORNIA.
THIS WILL RESULT IN A BRIEF WARM-UP ON WEDNESDAY AND
THURSDAY...PRIMARILY ACROSS INLAND AREAS.

THE UPPER LOW THAT WILL DEVELOP OFFSHORE BY MIDWEEK IS FORECAST
TO LIFT TO THE NORTHEAST LATE IN THE WEEK AND ACROSS CALIFORNIA BY
SATURDAY. COOLING IS EXPECTED BEGINNING ON FRIDAY AS THE LOW
APPROACHES. MOST MODEL GUIDANCE HAS SUGGESTED THIS LOW WILL NOT
HAVE SUFFICIENT MOISTURE AND/OR INSTABILITY TO PRODUCE CONVECTIVE
PRECIPITATION IN OUR AREA LATE IN THE WEEK. HOWEVER...THE 00Z GFS
DEVELOPS PRECIP JUST OFFSHORE BY THURSDAY EVENING...AND THEN JUST
TO OUR EAST BY FRIDAY AFTERNOON. THERE IS NOT YET ENOUGH MODEL
SUPPORT TO JUSTIFY ADDING SHOWER/THUNDERSTORM CHANCES TO THE
FORECAST...BUT IT`S SOMETHING TO KEEP AN EYE ON FOR LATE IN THE
EXTENDED FORECAST PERIOD.

&&

.AVIATION...AS OF 4:30 AM PDT SUNDAY...STRATUS IS MORE EXTENSIVE
THIS MORNING AND COVERS MUCH OF THE SFO AND MRY BAY AREAS.
MARINE LAYER IS NOT AS WELL DEFINED AS THE AIRMASS ALOFT HAS
COOLED SLIGHTLY. THIS WILL MAKE IT A LITTLE EASIER TO MIX OUT THE
STRATUS. SOUTHERLY FLOW ALOFT WILL ALSO AID IN CLEARING OUT THE
STRATUS. EXPECTING STRATUS TO CLEAR SFO AT THE TYPICAL TIME OF
18Z WITH CLEARING OF THE APPROACH BY 19Z.

VICINITY OF KSFO...MVFR THROUGH 18Z. WEST WINDS GUSTING TO 22 KT
AFTER 21Z.

KSFO BRIDGE APPROACH...MVFR THROUGH 19Z.

MONTEREY BAY AREA TERMINALS...MVFR THROUGH 18Z.

&&

.MARINE...AS OF 2:49 AM PDT SUNDAY...WEAK LOW PRESSURE OFF THE
SOUTHERN CALIFORNIA COAST WILL KEEP LIGHT WINDS THROUGH TUESDAY.
HIGH PRESSURE WILL START TO BUILD OFF THE NORTHERN CALIFORNIA
COAST BRINGING INCREASING NORTHWEST WINDS. SEAS WILL BE MIXED
NORTHWEST SWELL AND LONG PERIOD SOUTH TO SOUTHWEST SWELL INTO NEXT
WEEK.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

$$

PUBLIC FORECAST: DYKEMA
AVIATION: W PI
MARINE: W PI


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