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000
FXUS66 KMTR 171751
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1051 AM PDT FRI MAY 17 2013

.DISCUSSION...AS OF 08:10 AM PDT FRIDAY...UPPER TROUGH SCOURED OUT
MOST OF THE CLOUD COVER HOWEVER PATCHES OF LOW CLOUDS REMAIN AROUND SF
BAY AND EASTERN MRY BAY. DID A QUICK UPDATE TO REFLECT THE MOSTLY CLEAR
SKIES. OTHERWISE FORECAST LOOKS ON TRACK FOR SLIGHTLY COOLER
TEMPERATURES TODAY THEN GRADUAL WARM UP THROUGH MONDAY.

&&

.PREV DISCUSSION...AS OF 3:38 AM PDT FRIDAY...AN UPPER LEVEL TROUGH
CURRENTLY MOVING ACROSS THE DISTRICT HAS SCOURED OUT MOST OF THE
LOW CLOUDS ACROSS THE REGION. PATCHY CLOUDS REMAIN ANCHORED OVER
THE HILLS OF THE EAST BAY...SANTA CRUZ MOUNTAINS AND NORTHERN
MONTEREY AND SAN BENITO COUNTIES AS A RESULT OF LOW LEVEL
MOISTURE LEFT OVER FROM THE SCATTERED LIGHT RAIN THAT FELL ACROSS
THE AREA THURSDAY. LOW CLOUDS MAY EXPAND IN COVERAGE LATER THIS
MORNING BUT ARE EXPECTED TO CLEAR BY MIDDAY MAKING WAY FOR MOSTLY
CLEAR SKIES.

TEMPERATURES ARE FORECAST TO RUN SLIGHTLY BELOW NORMAL TODAY AS
A COOLER AIRMASS SETTLES IN OVER THE REGION AND COOL MARINE AIR
FILTERS IN AS A RESULT OF A MODERATE ONSHORE GRADIENT. WARMER
TEMPERATURES ARE FORECAST SATURDAY AS HIGH PRESSURE BUILDS AT THE
SURFACE AND ALOFT. THE GRADUAL WARMING TREND IS EXPECTED TO
PERSIST THROUGH MONDAY. SLIGHTLY ABOVE NORMAL TEMPERATURES ARE IN
STORE SUNDAY AND MONDAY WITH TEMPERATURES EXPECTED TO PEAK ON
MONDAY.

THE MARINE LAYER IS EXPECTED TO REESTABLISH ITSELF LATE TONIGHT
INTO SATURDAY WITH A DEPTH OF AROUND 1500 FEET OR LESS. HIGH
PRESSURE OVER THE REGION WILL LIKELY KEEP THE MARINE LAYER
RELATIVELY SHALLOW INTO EARLY NEXT WEEK.

MODELS INDICATE THE HIGH OVER THE EASTERN PACIFIC WILL RIDGE
ACROSS THE PACIFIC NORTHWEST AND INTO THE GREAT BASIN ON SUNDAY
CAUSING WINDS TO TURN NORTHERLY WITH A SLIGHT OFFSHORE COMPONENT.
AT THE SAME TIME A SHORTWAVE TROUGH SLIDING IN ALOFT OVER THE GREAT
BASIN WILL CAUSE WINDS TO STRENGTHEN ESPECIALLY OVER THE HILLS OF
THE NORTH AND EAST BAY. 925 MB WINDS SHOW WINDS AROUND 25 TO 30
KTS SUNDAY EVENING INTO MONDAY.

AS TEMPERATURES WARM SUNDAY INTO MONDAY AND DRY NORTHERLY WINDS
STRENGTHEN FIRE WEATHER CONCERNS WILL INCREASE. RED FLAG WARNINGS
ARE NOT EXPECTED AT THIS TIME DUE TO THE SHORT DURATION AND
STRENGTH OF THE WIND EVENT. HOWEVER CONDITIONS WILL NEED TO BE
MONITORED CLOSELY.

ON THE BRIGHT SIDE...SKIES SHOULD CLEAR NICELY MONDAY MAKING WAY
FOR A BEAUTIFULLY SUNNY DAY WITH TEMPERATURES WELL ABOVE NORMAL.
TEMPERATURES WILL RISE INTO THE 70S ALONG THE COAST WITH 80S TO
LOWER 90S INLAND. WARMEST INLAND LOCATIONS WILL SEE TEMPS RISE
INTO THE UPPER 90S WITH A FEW SITES POSSIBLY REACHING THE CENTURY
MARK.

BUT AS THEY SAY ALL GOOD THINGS MUST COME TO AND END AND SO SHALL
THIS WARMING TREND. MODELS SHOW AN UPPER LEVEL TROUGH MOVING IN
FROM THE NORTH BRINGING IN A SIGNIFICANTLY COOLER AIRMASS WHICH IS
EXPECTED TO COOL TEMPERATURES ACROSS THE REGION. TEMPERATURES WILL
SEE THE GREATEST DROP DURING THE SECOND HALF OF THE WEEK AS THE
LOW SLIDES SOUTH ACROSS THE FORECAST AREA. THE NORTH BAY MAY SEE
PRECIP FROM THIS SYSTEM HOWEVER WILL CONTINUE TO WATCH TO SEE HOW
THIS SYSTEM DEVELOPS BEFORE NAILING DOWN THE TIMING OR COVERAGE.

&&

.AVIATION...AS OF 10:40 AM PDT FRIDAY...CURRENT SATELLITE PICS
SHOW STRATUS BANKED UP ON THE WESTERN SIDE OF THE COASTAL
MOUNTAINS AND MAJOR TERMINALS REMAIN CLEAR. WITH A WESTERLY
FLOW...THERE SHOULD BE AN EARLY RETURN OF LOWER CLOUDS AND REDUCED
CIGS THIS EVENING AFTER 02-04Z. MVFR-IFR CIGS EXPECTED AT ALL
TERMINALS OVERNIGHT WITH LOW CLOUDS...BURNING OFF BY 14-17Z SAT AT
ALL TERMINALS WITH PERSISTENT WESTERLY FLOW.

VICINITY OF KSFO...VFR CONDITIONS SHOULD PERSIST THROUGH 03Z SAT WITH
AN EARLY RETURN OF LOW CLOUDS GIVEN THE WEST WINDS. MVFR CIGS
EXPECTED OVERNIGHT WITH BURN OFF AROUND 16Z SAT. WEST WINDS
INCREASING TO AROUND 20 KTS WITH GUSTS TO 27 KTS 21Z FRI-03Z SAT.

KSFO BRIDGE APPROACH...CIGS WILL LOWER IN THE VICINITY OF KSFO
FIRST AFTER 00Z THIS EVENING AND SPREAD SOUTH TO APPROACH.

MONTEREY BAY AREA TERMINALS...MVFR CIGS WILL RETURN AFTER 02Z SAT
AND PERSIST THROUGH 15-17Z SAT. WEST WINDS AROUND 10-15 KTS THROUGH
00Z SAT THEN DECREASING.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT ARENA TO PT REYES 0-10 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...SF BAY FROM 1 PM
             SCA...MRY BAY FROM 1 PM

&&

$$

PUBLIC FORECAST: CW
AVIATION/MARINE: JOHNSON

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