000
FXUS66 KMTR 170604
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1104 PM PDT THU MAY 16 2013

.DISCUSSION...AS OF 9:00 PM PDT THURSDAY...THE WEATHER SYSTEM THAT
PRODUCED SCATTERED LIGHT PRECIPITATION ACROSS OUR REGION EARLY
TODAY HAS MOVED WELL OFF TO OUR EAST AND RAIN HAS LONG SINCE
ENDED. SKIES BECAME MOSTLY CLEAR BY LATE IN THE DAY BUT RECENT
SATELLITE IMAGERY REVEALS EXPANDING AREAS OF LOW CLOUDS NEAR THE
OCEAN AND AROUND SF BAY. WITH PLENTY OF LOW LEVEL MOISTURE IN
PLACE...AS WELL AS MODERATE ONSHORE FLOW...WOULD EXPECT LOW CLOUDS
TO BECOME MORE WIDESPREAD AS THE NIGHT PROGRESSES. FRIDAY WILL
START OUT WITH PLENTY OF LOW CLOUD COVER...BUT WITH NO STRONG
MARINE INVERSION IN PLACE AND MODERATE NORTHWESTERLY FLOW TO
PROVIDE MIXING...EXPECT MOST AREAS TO CLEAR BY MIDDAY. ONLY A FEW
LOCATIONS NEAR THE OCEAN MAY REMAIN UNDER LOW CLOUDS INTO THE
AFTERNOON HOURS. TEMPERATURES WILL BE SLIGHTLY BELOW NORMAL IN
MOST AREAS TOMORROW AS WE REMAIN IN COOL NORTHWESTERLY FLOW.

A WARMING TREND IS FORECAST FROM SATURDAY THROUGH MONDAY AS AN
UPPER RIDGE OVER THE EASTERN PACIFIC GRADUALLY BUILDS JUST
OFFSHORE ALONG 130W. TEMPERATURES ARE EXPECTED TO WARM TO LEVELS
THAT ARE AT LEAST A FEW DEGREES ABOVE NORMAL BY SUNDAY. A MARINE
LAYER WILL DEVELOP BY FRIDAY NIGHT AND GRADUALLY BECOME MORE
SHALLOW OVER THE WEEKEND. BY SUNDAY...EXPECT ONLY PATCHY LOW
CLOUDS AND FOG NEAR THE IMMEDIATE COAST.

A SHORTWAVE TROUGH DROPPING INTO THE NORTHERN GREAT BASIN ON
SUNDAY WILL RESULT IN INCREASING NORTHERLY WINDS IN THE HILLS FROM
LATE SUNDAY INTO SUNDAY NIGHT AS SURFACE HIGH PRESSURE BUILDS TO
OUR NORTH AND NORTHEAST. THE STRONGEST WINDS WILL BE IN THE NORTH
AND EAST BAY HILLS. THE 00Z NAM FORECASTS NORTHERLY WINDS UP TO 30
KNOTS AT THE 925 MB LEVEL ACROSS THE NORTH BAY BY LATE SUNDAY
EVENING. GUSTY NORTHERLY WINDS WILL CONTINUE THROUGH SUNDAY
NIGHT...AND THEN RAPIDLY DIMINISH DURING THE DAY ON MONDAY. THESE
DRY NORTH WINDS WILL RAISE FIRE WEATHER CONCERNS...BUT AT THE
PRESENT TIME IT LOOKS AS THOUGH THE OFFSHORE WIND EVENT FROM LATE
SUNDAY NIGHT THROUGH EARLY MONDAY WON`T BE STRONG ENOUGH...OR LAST
LONG ENOUGH...TO WARRANT RED FLAG WARNINGS.

THE INCREASED NORTHERLY FLOW BEGINNING LATE SUNDAY WILL QUICKLY
DRY OUT THE AIRMASS ACROSS OUR REGION AND CLEAR ANY REMAINING LOW
CLOUDS AND FOG FROM THE COAST. MONDAY SHOULD BE A SUNNY DAY IN ALL
AREAS WITH TEMPERATURES WARMING INTO THE 70S NEAR THE OCEAN...AND
80S AND LOWER 90S INLAND. WE MAY EVEN SEE A FEW MID TO UPPER 90S
ACROSS THE SOUTHERN INTERIOR PART OF OUR AREA WHERE 850 MB TEMPS
ARE FORECAST TO CLIMB TO NEAR 20 DEG C.

THE WARMING TREND WILL COME TO AN ABRUPT END ON TUESDAY AS A COLD
UPPER TROUGH APPROACHES FROM THE NORTHWEST. TUESDAY`S COOLING WILL
MOSTLY BE DUE TO INCREASING ONSHORE FLOW IN ADVANCE OF THE UPPER
TROUGH. BUT THEN A MUCH COOLER AIRMASS WILL SWEEP ACROSS OUR AREA
DURING THE SECOND HALF OF NEXT WEEK AND DROP TEMPERATURES WELL
BELOW NORMAL...ESPECIALLY FOR INLAND AREAS...BY WEDNESDAY AND
THURSDAY. NEARLY ALL PRECIP WITH THIS COOL SYSTEM IS FORECAST TO
REMAIN TO OUR NORTH DURING THE SECOND HALF OF NEXT WEEK.

&&

.AVIATION...AS OF 10:55 PM PDT THURSDAY...INTERESTING EVOLUTION TO
COASTAL STRATUS THIS EVENING AS STARTED TO COME IN EARLY...THEN
CLEARED BACK TO NEAR COAST...AND NOW REDEVELOPING AND MORE
ROBUSTLY BEGINNING TO EXPAND INLAND. CIGS CURRENTLY EXIST AT BOTH MRY
BAY TERMINALS AND KSFO...AND ARE EXPECTED TO DEVELOP AT REMAINING
TERMINALS WITHIN THE NEXT COUPLE OF HOURS. CONTINUE TO EXPECT LOW
CLOUD COVERAGE TO BE WIDESPREAD BY MORNING...BUT NEW 00Z NAM MODEL
MOS GUIDANCE AND KSFO BUFR SOUNDING SUGGEST CLEARING ON FRIDAY A
BIT EARLIER THAN PREVIOUS THINKING AND HAVE MADE SOME
CORRESPONDING ADJUSTMENTS TO THE TAFS.

VICINITY OF KSFO...EXPECT MVFR CIG TO CONTINUE THROUGH THE NIGHT
AND INTO FRIDAY MORNING. HAVE MOVED UP CLEARING TIME ON FRIDAY A
BIT FROM PREVIOUS TAF...BUT CONFIDENCE IS LOW. ONSHORE FLOW LOOKS
TO REDEVELOP FRIDAY AFTERNOON SIMILAR TO TODAY.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIG AT KMRY EXPECTED TO CONTINUE
THROUGH THE NIGHT...WITH SOME POSSIBILITY OF LOWERING TO LIFR.
KSNS MVFR CIG WILL SIMILARLY CONTINUE...WITH CHANCE OF LOWERING TO
IFR. CURRENT INDICATIONS ARE THAT CLEARING ON FRIDAY WILL OCCUR
AROUND MIDDAY...A BIT EARLIER AT KSNS THAN KMRY...BUT COULD BE
DELAYED INTO THE EARLY AFTERNOON AT THE LATTER.

&&

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

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: BLIER

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