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Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
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FXUS66 KMTR 140340
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
840 PM PDT THU JUN 13 2013

.DISCUSSION...AS OF 8:40 PM PDT THURSDAY...STRONG SURFACE HIGH
PRESSURE OVER THE EASTERN PACIFIC IS NOSING INLAND ACROSS THE
PACIFIC NORTHWEST AND FAR NORTHERN CA THIS EVENING. AT 8 PM THE
SURFACE PRESSURE GRADIENT FROM ACV TO SFO WAS A ROBUST 8.5 MB.
THIS STEEP GRADIENT WAS DRIVING GALE FORCE GUSTS OVER THE COASTAL
WATERS AND AND PROVIDING SUFFICIENT LOW LEVEL MIXING TO MAINTAIN
CLEAR SKIES ACROSS OUR ENTIRE FORECAST AREA. THE MODELS BUILD THE
SURFACE RIDGE FARTHER INLAND TO OUR NORTH AND NORTHEAST OVERNIGHT
WHICH WILL RESULT IN WINDS VEERING MORE TO THE NORTH AND
INCREASING IN THE HILLS...BRINGING A DRIER AIRMASS INTO THE
REGION. THESE DEVELOPMENTS WILL MEAN IT`S VERY UNLIKELY WE WILL
SEE ANY COASTAL FOG AND LOW CLOUDS DEVELOP OVERNIGHT. ALSO...THE
COMBINATION OF DRIER NORTHERLY FLOW AND SLIGHT AIRMASS WARMING
ALOFT WILL MEAN WARMER TEMPERATURES IN ALL AREAS ON FRIDAY. A
FORECAST UPDATE COMPLETELY EARLIER THIS EVENING INCLUDED A
REDUCTION IN COASTAL LOW CLOUDS AND FOG FOR THIS EVENING AND
OVERNIGHT AS WELL AS AN INCREASE IN HIGH TEMPERATURES
TOMORROW...ABOUT 3 TO 5 DEGREES ABOVE WHAT WAS PREVIOUSLY
FORECAST. AFTERNOON HIGHS TOMORROW WILL RANGE FROM THE 60S AND
LOWER 70S NEAR THE OCEAN...MID 70S TO LOWER 80S IN THE COASTAL
VALLEYS...AND MID 80S TO LOWER 90S FOR THE INLAND VALLEYS.

LOCALLY BREEZY CONDITIONS CONTINUE IN THE HILLS THIS EVENING WITH
ISOLATED NORTHWEST WIND GUSTS UP TO 30 MPH. WINDS WILL PROBABLY
INCREASE A BIT MORE IN THE HILLS OVERNIGHT AS THEY VEER TO THE
NORTH. THESE NORTHERLY WINDS WILL BRING IN A DRIER AIRMASS AND
HUMIDITY RECOVERIES IN THE HILLS OVERNIGHT WILL BE RATHER POOR.
THE COMBINATION OF LOCALLY GUSTY NORTH WINDS AND DRIER AIR ARE
RAISING FIRE WEATHER CONCERNS TO SOME EXTENT. CONDITIONS ARE NOT
EXPECTED TO BE WINDY ENOUGH AND/OR DRY ENOUGH TO WARRANT RED FLAG
WARNINGS...BUT HEADLINES CONCERNING GUSTY DRY WINDS TONIGHT HAVE
BEEN ADDED TO THE FIRE WEATHER FORECAST. WINDS WILL DIMINISH IN
THE HILLS BY MIDDAY FRIDAY.

FRIDAY WILL BE THE WARMEST DAY OUR AREA WILL SEE FOR A WHILE. A
COOLING TREND IS FORECAST OVER THE WEEKEND AS AN UPPER TROUGH
DEVELOPS OFF THE WEST COAST AND MODERATE ONSHORE FLOW RETURNS. IN
FACT...ONSHORE FLOW WILL BEGIN TO INCREASE ON FRIDAY NIGHT AND A
MARINE LAYER WITH EXTENSIVE COASTAL LOW CLOUDS WILL LIKELY DEVELOP
BY SATURDAY MORNING. ADDITIONAL COOLING WILL THEN TAKE PLACE FROM
MONDAY THROUGH WEDNESDAY OF NEXT WEEK...ESPECIALLY INLAND...AS THE
UPPER TROUGH MOVES SLOWLY EASTWARD TOWARDS THE COAST. INLAND
TEMPERATURES WILL BE UP TO TEN DEGREES BELOW NORMAL BY TUESDAY AND
WEDNESDAY. THE UPPER TROUGH SHOULD BE STRONG ENOUGH TO MIX OUT THE
MARINE LAYER BY TUESDAY AND SO COASTAL TEMPERATURES PROBABLY WON`T
COOL MUCH MORE AFTER MONDAY AND MAY EVEN WARM A BIT DUE TO
INCREASED SUNSHINE.

WARMING IS EXPECTED FOR INLAND AREAS LATE NEXT WEEK ONCE THE UPPER
TROUGH MOVES OFF TO OUR EAST.

&&

.AVIATION...AS OF 4:40 PM PDT THURSDAY...MODERATE TO STRONG SFO
ACV GRADIENT CONTINUES TO KEEP LOW CLOUDS OUT OF THE AREA. ONSHORE
GRADIENT NOT QUITE AS STRONG AS YESTERDAY SO WINDS WILL NOT PEAK
QUITE AS HIGH THIS AFTERNOON. VFR THROUGH THE PERIOD EXCEPT FOR
PATCHY CIGS AROUND MRY EARLY TOMORROW.

VICINITY OF KSFO...VFR THROUGH THE FORECAST PERIOD. WEST WINDS IN
THE LOW TWENTIES THOUGH STRONGER GUSTS POSSIBLE IN THE NEXT FEW
HOURS...DIMINISHING AFTER 04Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR THROUGH THE PERIOD EXCEPT
POSSIBLE PATCHY CIGS EARLY TOMORROW AT MRY. LIGHT TO MODERATE
ONSHORE WINDS.

&&

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

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: AC

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