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000
FXUS66 KMTR 171516
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
816 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 4:40 AM PDT FRIDAY...DIFFICULT MORNING
FORECAST...AS PATCHY MVFR CIGS REMAIN NEAR MANY OF THE TERMINALS.
BOTH THE NAM AND LOCAL WRF INDICATE THAT ANY PATCHY CIGS WILL
DISSIPATE AROUND 16Z...SO TEMPO CIGS WERE ADDED THROUGH 16Z. VERY
LOW CONFIDENCE THAT CLOUDS WILL EVEN IMPACT TERMINALS.
OTHERWISE...WHERE CONFIDENCE REMAINS MUCH HIGHER...ONSHORE FLOW
WILL INCREASE SIGNIFICANTLY LATER THIS AFTERNOON INTO THE EARLY
EVENING HOURS.

VICINITY OF KSFO...POSSIBLE MVFR CIGS THROUGH 16Z. LOW CONFIDENCE.
MODERATE TO STRONG WEST WINDS AFTER 20Z...WITH WIND GUSTS NEAR 30
KT POSSIBLE THROUGH THE EARLY EVENING HOURS.

KSFO BRIDGE APPROACH...CIGS MORE LIKELY TO IMPACT THE APPROACH
THROUGH 16Z.

MONTEREY BAY AREA TERMINALS...POSSIBLE MVFR CIGS AT KMRY THROUGH
THE EARLY MORNING HOURS. LOW CONFIDENCE.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PT ARENA TO PT REYES 0-10 NM FROM 9 AM
             SCA...SF BAY FROM 1 PM
             SCA...MRY BAY FROM 1 PM

&&

$$

PUBLIC FORECAST: CW
AVIATION/MARINE: RILEY

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