000
FXUS66 KMTR 072143
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
243 PM PDT TUE SEP 7 2010

.DISCUSSION...AS OF 2:15 PM PDT TUESDAY...EXTENSIVE LOW CLOUDS COVER
THE COAST FROM JUST NORTH OF THE GOLDEN GATE DOWN THROUGH THE
MONTEREY COUNTY COAST. THE STRATUS IS BROKEN ALONG THE COAST IN
SONOMA COUNTY POSSIBLY DUE TO THE STRONG WINDS. THE MARINE LAYER AT
FT ORD HAS DEEPENED RAPIDLY TO 2300 FT AND ABOUT 1500 FT PER THE SAN
FRANCISCO SODAR.

THE UPPER TROUGH IS MAKING ITS INFLUENCE FELT ACROSS THE DISTRICT
TODAY AS SEEN ON THE GRADIENT PICTURE. THE ARCATA-SFO GRADIENT IS
ONLY 1.6 MB NORTHERLY WHEREAS THE SFO-SAC GRADIENT IS AT A ROBUST 4.2
MB ONSHORE. TEMPS HAVE TAKEN A DIVE...ANYWHERE FROM 16 TO 25 DEGREES
COOLER THAN YESTERDAY. THE WINDS THROUGH THE PASSES ARE QUITE
GUSTY...WITH THE ALTAMONT PASS GUSTING TO 40 MPH...AND PACHECO PASS
GUSTING TO 37 MPH.

UNUSUALLY DEEP TROUGH WILL CONTINUE TO DROP SOUTHEAST INTO THE
PACIFIC NW AND CA. HAVE KEPT THE MENTION OF STRATUS/FOG AND DRIZZLE
IN THE FORECAST...BUT WITH THE SATL IMAGERY INDC A FRACTURED STRATUS
PATTERN THIS MIGHT NOT HAPPEN. THE NEXT SHIFT WILL NEED TO SEE IF THE
STRATUS DECK REFORMS. MUCH BELOW TEMPS ARE IN STORE FOR TOMORROW AS
850 MB TEMPS DROP DOWN TO 7-8C. WITH THAT COLD TEMPS ALOFT THERE WILL
BE NO FOG WED NIGHT/THUR MORNING AS THE MARINE LAYER IS WIPED OUT.
HOWEVER...THE BOUNDARY LAYER WILL REMAIN MOIST SO THERE SHOULD BE
AMPLE STRATUS/STRATOCU CLOUDS.

THE TROUGH WILL LIFT TO THE NORTHEAST AS A SHORTWAVE RIDGE MOVES OVER
THE DISTRICT THUR EVENING THROUGH FRIDAY. THIS WILL BRING WARMER
TEMPS...TO NEAR NORMAL. WITH TEMPS ALOFT WARMING THE MARINE LAYER
SHOULD REFORM FOR STRATUS/FOG DURING THE NIGHT/MORNING HOURS.

YET ANOTHER TROUGH WILL DEEPEN ALONG THE COAST OVER THE WEEKEND INTO
NEXT WEEK. THIS WILL BRING A COOLING TREND BACK TO THE DISTRICT OVER
THE WEEKEND AND INTO NEXT WEEK.

&&

.AVIATION...AS OF 10:55 AM PDT TUESDAY...A TROUGH OF LOW PRESSURE
IS WORKING ITS WAY INTO THE WEST COAST THIS MORNING. THIS IS
RESULTING IN A MILD MARINE PUSH ALONG THE CENTRAL COAST. AS A RESULT
EXPECT STRATUS TO RETURN TO THE SF BAY AREA TERMINALS BY EARLY
AFTERNOON AND MVFR CIGS TO LINGER AROUND THE MONTEREY PENINSULA
TERMINALS THROUGHOUT THE DAY.

.VICINITY OF KSFO...VFR CIGS ARE EXPECTED TO PREVAIL THROUGH 2200Z.
A MILD MARINE PUSH WILL ADVECT MVFR CIGS INTO KSFO BY 2200Z WITH
ONSHORE WINDS 20 KT GUSTING TO 25 KT. WINDS WILL REMAIN ONSHORE
OVERNIGHT RANGING FROM 10 TO 15 KT.

.KSFO BRIDGE APPROACH...SIMILAR TO KSFO ALTHOUGH I FEEL THAT THE
CIGS WILL NOT REACH SAN MATEO BRIDGE UNTIL 0200 TO 0300Z.

.MRY BAY AREA TERMINALS...SLOW BURN OFF THIS MORNING WITH ONSHORE
FLOW ADVECTING MVFR CIGS INTO THE AREA. SOME BREAKS IN THE CLOUDS
MAY ALLOW FOR VFR AT KMRY LATER THIS MORNING HOWEVER...FEEL THAT
STRATUS WILL STILL LINGER IN KMRY AIRSPACE. KSNS WILL BE SLOWER TO
SCATTER OUT WITH VFR EXPECTED FROM 2000 TO 2300Z. WINDS WILL
REMAIN ONSHORE AT 10 TO 15 KT TODAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT....SCA...PT ARENA TO PIGEON PT 10 TO 60 NM
              SCA...PT ARENA TO PIGEON PT TO 10 NM
              SCA...SF BAY SAN PABLO SUISUN BAY AND THE WEST DELTA

&&

$$

PUBLIC FORECAST: MHS
AVIATION/MARINE: LARRY

NWS MTR Office Area Forecast Discussion