674
FXUS66 KMTR 142217
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
317 PM PDT MON APR 14 2025
..NEW SYNOPSIS, SHORT TERM, LONG TERM
SYNOPSIS
ISSUED AT 311 PM PDT MON APR 14 2025
A PATTERN CHANGE BEGINS ON TUESDAY BRINGING COLDER TEMPERATURES
TUESDAY INTO THURSDAY. WARM TEMPERATURES RETURN BY THE WEEKEND.
SLIGHT CHANCE FOR THUNDERSTORMS WEDNESDAY.
SHORT TERM
(THIS EVENING THROUGH TUESDAY)
ISSUED AT 311 PM PDT MON APR 14 2025
AS THE RIDGE STARTS TO EXIT TO THE EAST AND MAKES WAY FOR THE UPPER
LEVEL LOW TO TAKE INFLUENCE OVER OUR AREA, TEMPERATURES WILL BEGIN
TO LOWER. OVERNIGHT TEMPERATURES WILL SEE ABOUT 2-6 DEGREES
DIFFERENCE FROM LAST NIGHT TO TONIGHT WITH TEMPERATURES IN THE MID
TO HIGH 40S. THE MAX TEMPERATURES ON TUESDAY WILL SHOW A MORE
NOTICEABLE DIFFERENCE WITH A 6-12 DEGREES DIFFERENCE INLAND.
ALONG THE COAST, TEMPERATURES WILL BE IN THE UPPER 50S TO 60S FOR
THE MOST PART, BUT INLAND AREAS WILL DROP TO WIDESPREAD 60S, WITH
HIGHER TERRAIN SEEING UP TO LOW 70S. THE MARINE LAYER WILL REBUILD
TONIGHT BRINGING ANOTHER ROUND OF FOG AND/OR DRIZZLE ALONG THE
COAST EARLY TUESDAY MORNING. THERE IS A CHANCE THAT THE FOG WILL
PUSH FURTHER INLAND NEAR NORTH BAY AND MONTEREY BAY AS WELL.
MODELS DO SHOW A SIGNAL FOR SOME INSTABILITY OVERNIGHT INTO EARLY
TUESDAY MORNING. WHILE THE PROBABILITY OF THUNDERSTORMS (AROUND 15-
20%) PEAKS LATE WEDNESDAY INTO THURSDAY, WE WILL NEED TO MONITOR
TRENDS FOR CONVECTION LATE THIS EVENING AND INTO THE PRE-DAWN HOURS
ON TUESDAY, ALTHOUGH PROBABILITY IS VERY LOW. STEEP MID-LEVEL LAPSE
RATES ON THE ORDER OF 8 C/KM ARE ANTICIPATED TO OVERSPREAD THE
REGION FROM THE SOUTH AND SOUTHEAST AND PRECIPITABLE WATER VALUES
WILL INCH ABOVE 0.75", BUT THE BULK OF THE UPPER LEVEL MOISTURE
REMAINS DISPLACED FROM THE LIFT. THEREFORE, WE WILL CONTINUE TO
MONITOR THE TRENDS FOR TONIGHT INTO TUESDAY MORNING.
LONG TERM
(TUESDAY NIGHT THROUGH NEXT SUNDAY)
ISSUED AT 311 PM PDT MON APR 14 2025
THE UPPER LEVEL LOW THAT SITS OFF THE COAST OF SOUTHERN CA CONTINUES
TO STRENGTHEN AND WILL GRADUALLY MOVE INLAND. THIS WILL ALLOW FOR A
RETURN OF PREDOMINATELY ONSHORE FLOW AND COLDER TEMPERATURES, ALONG
WITH AN INCREASE IN CLOUD COVER AND MOISTURE FROM THE SOUTH. MODELS
CONTINUE TO SHOW AGREEMENT THAT THE LOW PRESSURE SYSTEM WILL BRING
SOME UNSTABLE ATMOSPHERE OVER OUR AREA WEDNESDAY AFTERNOON AND
CONDITIONS LOOK A BIT MORE FAVORABLE FOR HIGH-BASED CONVECTION.
ALSO, SPC HAS HIGHLIGHTED OUR AREA UNDER A GENERAL RISK FOR
THUNDERSTORM. THEREFORE, WE HAVE ADDED A CHANCE (15-20%) FOR
ISOLATED THUNDERSTORMS FOR WEDNESDAY, ESPECIALLY IN THE AFTERNOON.
IN ADDITION, WITH THE DEEPENING OF THE MARINE LAYER, THERE IS A
CHANCE FOR MORNING COASTAL FOG AND DRIZZLE.
ON FRIDAY, CLUSTER ANALYSIS SHOWS A REASONABLE AGREEMENT FOR ANOTHER
RIDGE PUSHING IN FROM THE EAST PACIFIC, BRINGING BACK SOME WARMER
TEMPERATURES AND DRIER CONDITIONS FOR THE WEEKEND. SO FAR, INLAND
AREAS ARE EXPECTED TO REACH IN THE MID TO HIGH 70S, WHICH REFLECTS
CLOSE TO NORMAL AVERAGE TEMPERATURES.
AVIATION
(18Z TAFS)
ISSUED AT 1056 AM PDT MON APR 14 2025
LIFR CONDITIONS BEGINNING TO IMPROVE TO MVFR/IFR ALONG COASTAL AND
COASTAL ADJACENT TERMINALS AT THIS HOUR WITH THE EXCEPTION BEING
KHAF. INLAND SITES ARE VFR AND WILL LIKELY REMAIN THAT WAY FOR THE
REMAINDER OF THE DAY WITH ONSHORE WINDS INCREASING TO ABOUT 09-14
KT BY THIS AFTERNOON. WINDS EASE OVERNIGHT WITH COASTAL SITES LIKELY
TO SEE MVFR CEILINGS DEVELOP LATE TONIGHT AND THEN IFR/LIFR
CEILINGS/VISIBILITIES RETURN EARLY TUESDAY MORNING. INLAND SITES ARE
LESS LIKELY TO SEE IFR/LIFR CONDITIONS, BUT MORE LIKELY TO BE MVFR
TO HIGH END IFR EARLY TUESDAY. THESE LOW CLOUDS AND/OR FOG ARE
FORECAST TO LIFT BY TUESDAY AFTERNOON ACROSS MUCH OF THE REGION.
VICINITY OF SFO...VFR THROUGH THIS AFTERNOON, THEN INCREASING
CLOUDINESS THIS EVENING AND OVERNIGHT. ONSHORE WINDS WILL INCREASE
THIS AFTERNOON AND PERSIST THROUGH THIS EVENING. CONFIDENCE IS LOWER
THAN NORMAL FOR MVFR/IFR CIGS EARLY TUESDAY MORNING THANKS TO THE
WEAK UPPER LEVEL DISTURBANCE AND PRESENCE OF MID AND UPPER
LEVEL CLOUDS DISRUPTING OUTGOING LONGWAVE RADIATION. ONSHORE WINDS
INCREASE ONCE AGAIN TUESDAY AFTERNOON, BUT NOTHING TO OVERLY
STRONG.
SFO BRIDGE APPROACH...SIMILAR TO SFO. LOWER CONFIDENCE FOR MVFR
CEILINGS TO DEVELOP OVER THE APPROACH EARLY TUESDAY MORNING, BUT
WILL BE QUICKER TO DISSIPATE IF THEY DO.
MONTEREY BAY TERMINALS...BECOMING VFR ONCE LOW CLOUDS DISSIPATE.
ONSHORE WINDS INCREASE THIS AFTERNOON TO AROUND 7-10 KT. WINDS
EASE LATE THIS EVENING AND INTO THE OVERNIGHT WITH IFR/LIFR
CEILINGS/VISIBILITIES LIKELY TO RETURN.
MARINE
(TODAY THROUGH SATURDAY)
ISSUED AT 1056 AM PDT MON APR 14 2025
GENTLE TO MODERATE NORTHERLY BREEZES ARE EXPECTED TODAY WHICH
WILL BE ACCOMPANIED WITH SUBSIDING SEAS. MODERATE SEAS HOLD
THROUGH MID WEEK OR SO, AND THEN BUILD INTO THE LATTER PORTION OF
THE WORK WEEK. WINDS WILL INCREASE AS WELL AND ANOTHER ROUND OF
SMALL CRAFT ADVISORIES MAY BE NEEDED.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
SHORT TERM...SO
LONG TERM....SO
AVIATION...RGASS
MARINE...RGASS
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