890
FXUS66 KMTR 200530
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1030 PM PDT SUN MAY 19 2013
.DISCUSSION...AS OF 8:20 PM PDT SUNDAY...CLEAR SKIES PREVAIL ACROSS
ALL OF OUR DISTRICT WITH EVEN THE COAST AND COASTAL WATERS ENTIRELY
FREE OF ANY MARINE STRATUS. HIGH TEMPERATURES THIS AFTERNOON WERE
GENERALLY IN THE 70S AROUND SAN FRANCISCO BAY AND THE 80S IN THE
VALLEYS...ABOUT 5 TO 8 DEG WARMER THAN ON SATURDAY. NEW 00Z NAM
VERY CONSISTENT WITH PRIOR RECENT RUNS IN ITS PROJECTION OF
MODERATE OFFSHORE WINDS DEVELOPING IN THE HIGHER HILLS OF THE
NORTH AND EAST BAY LATE TONIGHT. LATEST OUTPUT ALSO REMAINS
LARGELY UNCHANGED IN BOTH ITS GENERAL DEPICTION OF THE SYNOPTIC
EVOLUTION OVER THE NEXT 24 HOURS...AND IN THE RESULTING BIAS
CORRECTED GRIDDED MAX TEMP FORECASTS FOR MONDAY. THUS CONTINUE TO
EXPECT THAT WE'LL SEE AN ADDITIONAL 5 TO 8 DEG OF WARMING FOR
TOMORROW AFTERNOON...WITH HIGHS THEN REACHING INTO THE UPPER 70S
TO MID 80S AROUND SF BAY...AND TO THE LOWER 90S IN THE WARMEST BAY
AREA INLAND LOCATIONS. CURRENT FORECASTS APPEAR ON TRACK AND NO
UPDATES ARE PRESENTLY ANTICIPATED.
FROM PREVIOUS DISCUSSION...A SIGNIFICANT WEATHER CHANGE IS IN
STORE FOR OUR AREA BEGINNING TUESDAY. AN UNSEASONABLY COOL UPPER
TROUGH DROPPING SOUTHEAST OUT OF THE GULF OF ALASKA WILL BRING A
MUCH COOLER AIRMASS INTO NORTHERN AND CENTRAL CALIFORNIA BY LATE
TUESDAY AND TUESDAY NIGHT. 850 MB TEMPERATURES ARE FORECAST TO
PLUMMET FROM NEAR 20 DEG C ON MONDAY DOWN TO AS LOW AS 2 DEG C BY
TUESDAY NIGHT. IN ADDITION...STRONG ONSHORE FLOW WILL DEVELOP BY
TUESDAY AFTERNOON. HIGH TEMPERATURES ON TUESDAY WILL BE 15 TO 20
DEGREES COOLER COMPARED TO MONDAY. ONLY THE FAR SOUTHERN INTERIOR
PART OF OUR AREA WILL ESCAPE MAJOR COOLING ON TUESDAY. BUT ALL
AREAS WILL SEE TEMPERATURES FALL WELL BELOW NORMAL BY WEDNESDAY.
NORTHWESTERLY WINDS WILL QUICKLY INCREASE ON TUESDAY AFTER A DRY
COLD FRONT SWEEPS ACROSS THE REGION. BY LATE TUESDAY AFTERNOON
PORTIONS OF OUR AREA MAY SEE WIND GUSTS UP TO 50 MPH. THE GFS MOS
GUIDANCE IS FORECASTING SUSTAINED WINDS OF 32 KNOTS AT SFO AT 21Z
TUESDAY AFTERNOON. STRONGEST WINDS ON TUESDAY AFTERNOON AND EARLY
EVENING WILL BE NEAR THE COAST OF THE SF BAY AREA. WINDS WILL
GRADUALLY DECREASE NEAR THE COAST OVERNIGHT TUESDAY NIGHT...BUT
REMAIN STRONG AND GUSTY IN THE COASTAL HILLS THROUGH MUCH OF
TUESDAY NIGHT. A HAZARDOUS WEATHER OUTLOOK HAS BEEN ISSUED TO DRAW
ATTENTION TO THE POSSIBILITY OF LOCALLY STRONG WINDS FOR COASTAL
AREAS OF THE SF BAY AREA ON TUESDAY AND TUESDAY NIGHT. A WIND
ADVISORY MAY BE NEEDED FOR THIS EVENT.
TEMPERATURES BY WEDNESDAY WILL BE UP TO 10 DEGREES BELOW NORMAL
AND COOL CONDITIONS WILL PERSIST THROUGH THE END OF THE WEEK AS
THE UPPER TROUGH REMAINS ANCHORED NEAR THE WEST COAST. THE MODELS
CONTINUE TO KEEP ALL PRECIP WITH THIS SYSTEM TO OUR NORTH...SO THE
MAIN IMPACT IN OUR AREA WILL BE COOL AND BREEZY CONDITIONS. WINDS
WILL LIKELY BE STRONGEST ON TUESDAY AND TUESDAY NIGHT...BUT
BREEZY CONDITIONS WILL PERSIST THROUGH THE END OF THE WEEK.
WE WILL LIKELY SEE A BRIEF RETURN OF COASTAL LOW CLOUDS LATE
MONDAY NIGHT AND TUESDAY MORNING. BUT BY TUESDAY AFTERNOON THERE
WILL BE ENOUGH COOL ADVECTION TO WIPE OUT THE MARINE LAYER AND
MARINE LAYER LOW CLOUDS WILL BE ABSENT FROM OUR AREA FOR THE
REMAINDER OF THE WEEK. TEMPERATURE CONTRASTS FROM THE COAST TO
INLAND AREAS BY MIDWEEK WILL BE MUCH LESS THAN TYPICAL FOR THIS
TIME OF YEAR...ONLY ABOUT 10 DEGREES OR SO.
THE UPPER TROUGH IS FORECAST TO LIFT TO THE NORTHEAST BY NEXT
WEEKEND...SO TEMPERATURES SHOULD BEGIN TO WARM THEN. HOWEVER...THE
MODELS MAINTAIN A WEAK UPPER TROUGH NEAR THE WEST COAST AND SO
TEMPERATURES WILL LIKELY REMAIN BELOW NORMAL INTO NEXT
WEEKEND...ESPECIALLY FOR INLAND AREAS.
&&
.AVIATION...AS OF 10:30 PM PDT SUNDAY...DRY NORTHERLY FLOW WILL
KEEP VFR CONDITIONS IN THE SFO BAY AREA THROUGH MONDAY. WEAK
MARINE LAYER EXISTS NEAR 1000 FEET AND THERE COULD BE PATCHY
STRATUS IN THE MRY BAY AREA EARLY MONDAY.
VICINITY OF KSFO...VFR THROUGH MONDAY. WIND GUSTS TO 30 KT
THROUGH 05Z.
KSFO BRIDGE APPROACH...SIMILAR TO KSFO.
MONTEREY BAY AREA TERMINALS...PATCHY STRATUS WILL BE POSSIBLE
AT KMRY...SIMILAR TO THE PAST FEW EVENINGS.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 AM
SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 AM
SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 AM
SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 3 AM
SCA...PT ARENA TO PT REYES 0-10 NM
SCA...PT ARENA TO PIGEON PT 10-60 NM
&&
$$
PUBLIC FORECAST: DYKEMA/BLIER
AVIATION/MARINE: W PI
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