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000
FXUS66 KMTR 170535
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1035 PM PDT SUN JUN 16 2013

.DISCUSSION...AS OF 9:00 PM PDT SUNDAY...A LONGWAVE UPPER TROUGH
IS CENTERED OFFSHORE ALONG 138W THIS EVENING. A WEAK SHORTWAVE
RIDGE EMBEDDED IN THE WSW FLOW AHEAD OF THE TROUGH MANAGED TO
SUPPRESS THE MARINE LAYER OVER OUR REGION TODAY. IN FACT...THE
MARINE LAYER DEPTH DECREASED FROM ABOUT 2000 FEET YESTERDAY
EVENING DOWN TO JUST 1000 FEET BY MIDDAY TODAY. THE RESULT WAS
EARLY CLEARING FOR INLAND AREAS AND WIDESPREAD CLEARING AT THE
COAST THIS AFTERNOON. WITH EXTRA SUN TODAY...TEMPERATURES WERE
WARMER COMPARED TO YESTERDAY AT NEARLY ALL REPORTING LOCATIONS.

THE MARINE LAYER REMAINS RELATIVELY SHALLOW THIS EVENING...1200
FEET DEEP ON THE OAK SOUNDING AND 1000 FEET DEEP AT FORT ORD.
WOULD EXPECT AT LEAST SOME DEEPENING OF THE MARINE LAYER OVERNIGHT
AND INTO MONDAY AS THE LONGWAVE TROUGH MOVES SLOWLY EASTWARD.
THUS...TEMPERATURES SHOULD COOL AT LEAST A FEW DEGREES ON MONDAY.
MUCH MORE SIGNIFICANT COOLING IS FORECAST FOR TUESDAY AS THE
UPPER TROUGH AXIS APPROACHES THE COAST AND A ROBUST SHORTWAVE
SWINGS THROUGH THE BASE OF THE LONGWAVE TROUGH. A STRONG MARINE
PUSH WILL PROBABLY GET UNDERWAY ON MONDAY NIGHT WITH PATCHY
DRIZZLE LIKELY...ESPECIALLY IN COASTAL AREAS...BY TUESDAY
MORNING. HIGHS ON TUESDAY WILL BE ANYWHERE FROM 7 TO 15 DEGREES
BELOW NORMAL...WITH GREATEST DEPARTURES FROM THE NORM EXPECTED
ACROSS INLAND AREAS. THE TROUGH AXIS IS FORECAST TO SWING INLAND
ON TUESDAY EVENING AND LOCALLY BLUSTERY CONDITIONS ARE EXPECTED IN
THE HILLS AND NEAR THE COAST FROM LATE TUESDAY AFTERNOON THROUGH
TUESDAY EVENING. THE AIRMASS ALOFT WILL COOL CONSIDERABLY BY LATE
TUESDAY...WITH 850 MB TEMPERATURES FORECAST TO DROP BELOW 10 DEG
C. THAT MUCH COOLING ALOFT SHOULD WIPE OUT THE MARINE INVERSION
AND HELP TO BREAK UP THE LOW STRATUS CLOUD DECK. BUT THE
PERSISTENT STRONG AND MOIST ONSHORE FLOW WILL LIKELY MAINTAIN AT
LEAST PARTLY CLOUDY SKIES THROUGH WEDNESDAY. TEMPERATURES ON
WEDNESDAY WILL REMAIN WELL BELOW NORMAL.

THE UPPER TROUGH WILL MOVE WELL EAST OF THE AREA BY THURSDAY AND
UPPER LEVEL RIDGING IS FORECAST TO GRADUALLY STRENGTHEN NEAR THE
WEST COAST FROM THURSDAY THROUGH NEXT WEEKEND. TEMPERATURES ARE
EXPECTED TO WARM BACK UP TO NEAR NORMAL BY FRIDAY AND THEN ABOVE
NORMAL BY SATURDAY.

&&

.AVIATION...AS OF 10:30 PM PDT SUNDAY...SATELLITE IMAGE SHOWS
STRATUS HAS CLEARED OFFSHORE. THIS APPEARS TO BE DUE TO A STRONG
NORTHERLY GRADIENT THAT HAS DEVELOPED. THE ACV-SFO PRESSURE
GRADIENT IS ONLY 2.8 MB BUT BELIEVE THE LOW PRESSURE OFF THE
PACNW IS KEEPING THE PRESSURE AT ACV LOWER AND THUS IT DOES NOT
REFLECT A STRONG N-S GRADIENT. A LOOK AT THE SFO-SBA GRADIENT DOES
SHOW THIS AS THIS GRADIENT HAS INCREASED FROM 1.7 MB LAST NIGHT TO
5.5 MB THIS EVENING. THE UPSHOT OF ALL THIS IS THAT THE STRATUS WILL BE
PATCHY IN THE MRY AND SFO BAY AREAS. LATEST FORECAST BRINGS IFR
CIGS INTO SFO AFTER 12Z BUT HAVE LESS CONFIDENCE IN THIS AS IT MAY
STAY CLEAR ALL NIGHT. MARINE LAYER IS DOWN TO 1000 FEET SO ANY
CIGS THAT COME IN WILL BE IFR.

VICINITY OF KSFO...VFR THROUGH AT LEAST 12Z AND POSSIBLY ALL NIGHT.

KSFO BRIDGE APPROACH...SIMILAR TO SFO.

MONTEREY BAY AREA TERMINALS...PATCHY STRATUS WILL DEVELOP ALONG
THE COAST AFTER 10Z BRINGING IFR CIGS TO MRY AND SNS AFTER 12Z.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: W PI

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