000
FXUS66 KMTR 192210
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
310 PM PDT SUN MAY 19 2013

.DISCUSSION...AS OF 3:10 PM PDT SUNDAY...SUBSIDENCE WARMING UNDER
A BUILDING RIDGE OF HIGH PRESSURE ALOFT...COMBINED WITH DECREASED
ONSHORE FLOW...HAS RESULTED IN WARMER TEMPERATURES TODAY. EARLY
AFTERNOON TEMPERATURES ARE RUNNING UP TO 10 DEGREES ABOVE WHAT
THEY WERE 24 HOURS AGO.

SURFACE HIGH PRESSURE HAS BEEN BUILDING INLAND TO OUR NORTH SINCE
LATE YESTERDAY AND IS FORECAST TO EXTEND INTO THE GREAT BASIN
OVERNIGHT. THE RESULT WILL BE THE DEVELOPMENT OF OFFSHORE FLOW
OVERNIGHT WITH SOME LOCALLY GUSTY NORTH TO NORTHEAST WINDS
EXPECTED IN THE HILLS. THE MODELS HAVE RECENTLY BACKED OFF QUITE
A BIT ON THE STRENGTH OF THESE OFFSHORE WINDS IN THE HILLS
OVERNIGHT AND SO FIRE WEATHER CONCERNS HAVE DECREASED.

MONDAY SILL APPEARS TO BE THE WARMEST DAY OF THE WEEK AS THE UPPER
RIDGE AXIS SHIFTS INLAND OVER CA AND LIGHT OFFSHORE FLOW PERSISTS
AT LEAST THROUGH MIDDAY. A SEABREEZE WILL DEVELOP IN THE
AFTERNOON...BUT COASTAL AREAS SHOULD HAVE ENOUGH TIME TO WARM INTO
THE 70S BY MIDDAY. HIGHS WILL BE IN THE 80S TO LOWER 90S INLAND
WITH EVEN SOME MID TO UPPER 90S LIKELY IN THE SOUTHERN INTERIOR OF
MONTEREY COUNTY AND SAN BENITO COUNTY.

A SIGNIFICANT WEATHER CHANGE IS IN STORE FOR OUR AREA BEGINNING
TUESDAY. AN UNSEASONABLY COOL UPPER TROUGH DROPPING SOUTHEAST OUT
OF THE GULF OF ALASKA WILL BRING A MUCH COOLER AIRMASS INTO
NORTHERN AND CENTRAL CALIFORNIA BY LATE TUESDAY AND TUESDAY NIGHT.
850 MB TEMPERATURES ARE FORECAST TO PLUMMET FROM NEAR 20 DEG C
ON MONDAY DOWN TO AS LOW AS 2 DEG C BY TUESDAY NIGHT. IN
ADDITION...STRONG ONSHORE FLOW WILL DEVELOP BY TUESDAY AFTERNOON.
HIGH TEMPERATURES ON TUESDAY WILL BE 15 TO 20 DEGREES COOLER
COMPARED TO MONDAY. ONLY THE FAR SOUTHERN INTERIOR PART OF OUR
AREA WILL ESCAPE MAJOR COOLING ON TUESDAY. BUT ALL AREAS WILL SEE
TEMPERATURES FALL WELL BELOW NORMAL BY WEDNESDAY.

NORTHWESTERLY WINDS WILL QUICKLY INCREASE ON TUESDAY AFTER A DRY
COLD FRONT SWEEPS ACROSS THE REGION. BY LATE TUESDAY AFTERNOON
PORTIONS OF OUR AREA MAY SEE WIND GUSTS UP TO 50 MPH. THE GFS MOS
GUIDANCE IS FORECASTING SUSTAINED WINDS OF 32 KNOTS AT SFO AT 21Z
TUESDAY AFTERNOON. STRONGEST WINDS ON TUESDAY AFTERNOON AND EARLY
EVENING WILL BE NEAR THE COAST OF THE SF BAY AREA. WINDS WILL
GRADUALLY DECREASE NEAR THE COAST OVERNIGHT TUESDAY NIGHT...BUT
REMAIN STRONG AND GUSTY IN THE COASTAL HILLS THROUGH MUCH OF
TUESDAY NIGHT. A HAZARDOUS WEATHER OUTLOOK HAS BEEN ISSUED TO DRAW
ATTENTION TO THE POSSIBILITY OF LOCALLY STRONG WINDS FOR COASTAL
AREAS OF THE SF BAY AREA ON TUESDAY AND TUESDAY NIGHT. A WIND
ADVISORY MAY BE NEEDED FOR THIS EVENT.

TEMPERATURES BY WEDNESDAY WILL BE UP TO 10 DEGREES BELOW NORMAL
AND COOL CONDITIONS WILL PERSIST THROUGH THE END OF THE WEEK AS
THE UPPER TROUGH REMAINS ANCHORED NEAR THE WEST COAST. THE MODELS
CONTINUE TO KEEP ALL PRECIP WITH THIS SYSTEM TO OUR NORTH...SO THE
MAIN IMPACT IN OUR AREA WILL BE COOL AND BREEZY CONDITIONS. WINDS
WILL LIKELY BE STRONGEST ON TUESDAY AND TUESDAY NIGHT...BUT
BREEZY CONDITIONS WILL PERSIST THROUGH THE END OF THE WEEK.

WE WILL LIKELY SEE A BRIEF RETURN OF COASTAL LOW CLOUDS LATE
MONDAY NIGHT AND TUESDAY MORNING. BUT BY TUESDAY AFTERNOON THERE
WILL BE ENOUGH COOL ADVECTION TO WIPE OUT THE MARINE LAYER AND
MARINE LAYER LOW CLOUDS WILL BE ABSENT FROM OUR AREA FOR THE
REMAINDER OF THE WEEK. TEMPERATURE CONTRASTS FROM THE COAST TO
INLAND AREAS BY MIDWEEK WILL BE MUCH LESS THAN TYPICAL FOR THIS
TIME OF YEAR...ONLY ABOUT 10 DEGREES OR SO.

THE UPPER TROUGH IS FORECAST TO LIFT TO THE NORTHEAST BY NEXT
WEEKEND...SO TEMPERATURES SHOULD BEGIN TO WARM THEN. HOWEVER...THE
MODELS MAINTAIN A WEAK UPPER TROUGH NEAR THE WEST COAST AND SO
TEMPERATURES WILL LIKELY REMAIN BELOW NORMAL INTO NEXT
WEEKEND...ESPECIALLY FOR INLAND AREAS.

&&

.AVIATION...AS OF 10:25 AM PDT SUNDAY...VFR CONDITIONS WILL
PREVAIL THROUGH THE FORECAST. OFFSHORE DRYING WINDS THIS MORNING
WILL TURN ONSHORE BY THE EARLY AFTERNOON HOURS AND CONTINUE INTO
THE EVENING HOURS.

VICINITY OF KSFO...VFR CONDITIONS THROUGH THE FORECAST. MODERATE
TO STRONG WEST WINDS WILL BE PRESENT THIS AFTERNOON AND
EVENING...WITH WIND GUSTS TO 30 KT POSSIBLE. MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WILL PREVAIL THROUGH
AT LEAST 06Z. PATCHY STRATUS WILL BE POSSIBLE EARLY THIS EVENING
AT KMRY...SIMILAR TO THE PAST FEW EVENINGS. OTHERWISE...MODERATE
ONSHORE WINDS THIS AFTERNOON.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 AM
             SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 AM
             SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 3 AM
             SCA...PT ARENA TO PT REYES 0-10 NM
             SCA...PT ARENA TO PIGEON PT 10-60 NM
             SCA...SF BAY UNTIL 9 PM
             SCA...MRY BAY UNTIL 9 PM

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: RILEY

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