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000
FXUS66 KMTR 211151
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
451 AM PDT TUE MAY 21 2013

.DISCUSSION...AS OF 2:40 AM PDT TUESDAY...AFTER A STRING OF NICE
MILD WEATHER...MUCH COOLER WEATHER IS IN STORE.

AN UPPER LEVEL LOW CURRENTLY NEAR 48N/131W IS EXPECTED TO BRING A
BIG CHANGE TO THE SENSIBLE WEATHER ACROSS THE REGION. LATEST
SATELLITE IMAGERY REVEALS WIDESPREAD HIGH CLOUDS COVERING MUCH OF
THE BAY AREA. SFC OBSERVATIONS INDICATE THAT UNDER THE HIGH
CLOUDS...A FEW PATCHY LOW CLOUDS EXIST AROUND 1K FEET. FORT ORD
PROFILER AND SODARS PUT THE DIFFUSE MARINE LAYER 1000-1200 FEET.

SHORT TERM(TODAY-THURSDAY)...
A FEW PATCHY LOW CLOUDS WILL BE POSSIBLE EARLY THIS MORNING...BUT
AMPLE HIGH CLOUDS AND A MODERATE N-S GRADIENT WILL KEEP WIDESPREAD
STRATUS FROM FORMING. MORE IMPORTANTLY TODAY WILL BE THE BIG COOL
DOWN AND BREEZY TO OCCASIONALLY GUSTY WINDS. THE AFOREMENTIONED
UPPER LOW IS FORECAST TO DROP S AND E INTO THE PACIFIC NORTHWEST
TODAY. AS A RESULT...MUCH COLDER AIR WILL FILTER OVER THE REGION.
COMPARING YESTERDAY/S MAX TEMPS TO THE PREDICTED MAX TEMPS FOR
TODAY SHOW A BIG DROP. IN FACT...PARTS OF THE NORTH BAY MAY BE AS
MUCH AS 20 DEGREES COLDER TODAY. OTHER LOCATIONS WILL LIKELY SEE
COLD DOWN OF 10 TO 15 DEGREES COMPARED TO MONDAY. GENERALLY
SPEAKING...HIGHS TODAY WILL BE IN THE 60S AT THE COAST AND 70S
INLAND...SOUTHERN INTERIOR UP TO THE UPPER 80S. THE COLD ADVECTION
ALOFT AND INCREASING ONSHORE FLOW WILL LEAD TO STRONGER
WINDS TODAY...BUT JUST BELOW WIND ADVISORY CRITERIA.
HOWEVER...GAPS AND PASSES...LIKE PACHECO...MAY SEE OCCASIONAL
GUSTS TO 40-45 MPH. DESPITE THE APPROACHING UPPER LOW...THE BAY
AREA IS EXPECTED TO REMAIN DRY. A FEW SHOWERS WILL BE
POSSIBLE...BUT WELL NORTH OF THE CWA.

FOR THE REST OF THE SHORT TERM...WINDS WILL EASE UP A BIT
WEDNESDAY AND THURSDAY....BUT SEASONABLY COOL TEMPERATURES WILL
REMAIN. SOME PATCHY NIGHT AND MORNING LOW CLOUDS WILL BE
POSSIBLE...BUT CURRENTLY NOT EXPECTING A WELL ESTABLISHED MARINE LAYER.

LONG TERM(FRIDAY-MONDAY)...
THE LONGWAVE PATTERN INDICATES AN OMEGA BLOCK COVERING MUCH OF THE
CONUS WITH AN UPPER LOW LINGERING AROUND THE PACIFIC NORTHWEST. H5
REBOUND SLIGHTLY ON FRIDAY PRODUCING SLIGHTLY WARMER 850MB TEMPS.
A FEW SHORTWAVE TROUGHS ROTATE AROUND THE PAC NW UPPER LOW THROUGH
NEXT WEEK...BUT WITH LITTLE FAN FARE. ALL THAT BEING SAID...DRY
WEATHER AND SEASONABLY COOL CONDITIONS WILL CONTINUE FOR THE
HOLIDAY WEEKEND.

&&

.AVIATION...AS OF 4:45 AM PDT TUESDAY...A MID LEVEL TROUGH WILL MOVE
SE ACROSS THE BAY AREA AND CENTRAL COAST LATER THIS MORNING AND EARLY
AFTERNOON. W-NW WINDS WILL INCREASE BEHIND THE TROUGH.

VICINITY OF KSFO...WEST WINDS WILL LIKELY INCREASE BY LATE MORNING.
VFR.

KSFO BRIDGE APPROACH...VFR.

MONTEREY BAY AREA TERMINALS...LOW CLOUDS WILL GRADUALLY MIX OUT AS
SURFACE WINDS INCREASE LATER THIS MORNING. VFR AFTER 16Z.

&&

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

&&

$$

PUBLIC FORECAST: MM
AVIATION/MARINE: CANEPA

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