292
FXUS66 KMTR 251021
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
321 AM PDT TUE MAR 25 2025
..NEW SYNOPSIS, SHORT TERM, LONG TERM, MARINE
SYNOPSIS
ISSUED AT 319 AM PDT TUE MAR 25 2025
SUMMERLIKE WARMTH CONTINUES TODAY WITH HIGHS IN THE MID TO UPPER
80S AND ISOLATED LOW 90S EXPECTED. SEASONAL TEMPERATURES RETURN
WEDNESDAY AS A WEAK SYSTEM MOVES THROUGH THE AREA. A SERIES OF
POTENTIALLY MORE IMPACTFUL SYSTEMS WILL ARRIVE THIS WEEKEND INTO
NEXT WEEK.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 319 AM PDT TUE MAR 25 2025
ABOVE NORMAL TEMPERATURES CONTINUE TODAY WITH HIGHS LARGELY
ANTICIPATED TO BE IN THE MID TO UPPER 80S. THE WARMEST AREAS WILL BE
IN INTERIOR MONTEREY AND SAN BENITO COUNTIES WHERE TEMPERATURES ARE
FORECAST TO BE IN THE LOW 90S. ACROSS THE BOARD, TEMPERATURES ARE
EXPECTED TO BE A FEW DEGREES HIGHER TODAY THAN THEY WERE YESTERDAY.
TO PROVIDE SOME CONTEXT AS TO WHY, MODEL GUIDANCE FOR MONDAY
INDICATED 850 MB TEMPS WOULD BE ABOUT 15C YESTERDAY BUT THE 00Z OAK
SOUNDING (TAKEN YESTERDAY AFTERNOON BETWEEN 4-5PM) SHOWED 850MB
TEMPS AROUND 16C. MODEL GUIDANCE IS FORECASTING 850MB TEMPERATURES
TO BE CLOSER TO 16C TO 17C TODAY WHICH WOULD SUPPORT TEMPERATURES
WARMING SLIGHTLY HIGHER THAN YESTERDAY. THE MAIN CAVEATS TO THE
TEMPERATURE FORECAST REMAIN IN WHEN WINDS WILL SWITCH FROM OFFSHORE
TO ONSHORE, HOW STRONG THOSE WINDS ARE, AND IF INCOMING HIGH LEVEL
CLOUDS WILL SIGNIFICANTLY DIMINISH HEATING AT THE SURFACE. IN TERMS
OF THE WIND, WINDS LOOK TO REMAIN FAIRLY LIGHT THROUGHOUT THE DAY
(GENERALLY LESS THAN 10 MPH). WINDS ARE FORECAST TO REMAIN OFFSHORE
THROUGH THE EARLY AFTERNOON BEFORE TRANSITIONING TO ONSHORE FLOW BY
MID AFTERNOON. BOTH THE RAP AND NAM MODELS FAVOR THIS SWITCH
OCCURRING BETWEEN 2-4PM WHILE THE GFS KEEPS WINDS WEAKLY OFFSHORE
THOROUGH THE EVENING HOURS. THE LONGER OFFSHORE WINDS PERSIST, THE
MORE LIKELY THE FORECASTED TEMPERATURES WILL BE ACHIEVED. IF THE
TRANSITION TO ONSHORE WINDS OCCURS EARLY IN THE DAY, TEMPERATURES
ARE LIKELY TO BE LOWER AS ONSHORE WINDS WILL TRANSPORT COOLER
OCEANIC AIR OVER THE LAND AND LIMIT THE AMOUNT OF SURFACE WARMING
THAT CAN OCCUR.
GUIDANCE CONTINUES TO FORECAST SUBSTANTIAL AMOUNTS OF CAPE ACROSS
THE BAY AREA AND CENTRAL COAST TUESDAY AFTERNOON/EVENING. IN TERMS
OF THUNDERSTORMS THERE ARE THREE MAIN INGREDIENTS YOU NEED: A
MOISTURE, INSTABILITY, AND A SOURCE OF LIFT. THE 00Z OAK SOUNDING
SHOWS PWAT VALUES AROUND 0.70 INCHES (WHICH REFERS TO THE MAXIMUM
AMOUNT OF WATER IN A COLUMN OF AIR IF ALL OF THE MOISTURE IN THAT
COLUMN WERE PRECIPITATED OUT OF IT) WITH FORECAST PWAT VALUES FOR
TUESDAY AFTERNOON IN THE RANGE OF 0.60-0.70 INCHES. WHILE NOT AS
MUCH AS WE CAN SEE DURING ATMOSPHERIC RIVER EVENTS, THIS IS ENOUGH
MOISTURE FOR SOME POTENTIAL STORM DEVELOPMENT. IN TERMS OF
INSTABILITY, HIGH CAPE VALUES SHOW THAT WE DO HAVE SOME INSTABILITY
PRESENT WITH DECENT CONDITIONALLY UNSTABLE LOW LEVEL LAPSE RATES.
HOWEVER, FORECAST SOUNDINGS SHOW BETWEEN 100 TO 300 J/KG OF CIN
ACROSS THE REGION WHICH IS A FAIRLY SUBSTANTIAL CAP THAT ANY
CONVECTION WOULD HAVE TO OVERCOME IN ORDER FOR STORMS TO DEVELOP. WE
ARE ALSO LACKING ANY SUBSTANTIAL LIFTING MECHANISM ACROSS THE REGION
WITH UPPER LEVEL RIDGING LOCATED OVER THE AREA. AS A RESULT
THUNDERSTORMS ARE UNLIKELY TO DEVELOP TOMORROW BUT IF A STORM IS
ABLE TO GAIN SOME SORT OF LIFTING MECHANISM (POTENTIALLY VIA
OROGRAPHIC LIFTING) AN ISOLATED THUNDERSTORM AND LOCALLY GUSTY WINDS
MAY BE POSSIBLE. HOWEVER, CONFIDENCE REMAINS LOW IN THUNDERSTORM
DEVELOPMENT WITH THE MOST LIKELY SCENARIO BEING THAT WE WILL SEE THE
DEVELOPMENT OF FAIR WEATHER CUMULUS CLOUDS ACROSS THE REGION.
LONG TERM
(WEDNESDAY THROUGH MONDAY)
ISSUED AT 319 AM PDT TUE MAR 25 2025
TEMPERATURES WILL COOL BACK DOWN TO SEASONAL VALUES WEDNESDAY
THROUGH THE END OF THE FORECAST PERIOD AS UPPER LEVEL RIDGING EXITS
THE REGION AND UPPER LEVEL TROUGHING MOVES IN. HIGHS WEDNESDAY WILL
GENERALLY BE IN THE MID 60S TO LOW 70S BEFORE A WEAK COLD FRONT
MOVES THROUGH WEDNESDAY INTO FRIDAY AND FURTHER DROPS TEMPERATURES.
LIGHT RAIN IS EXPECTED ACROSS THE BAY AREA WEDNESDAY INTO THURSDAY
WITH UP TO 0.5" ACROSS THE NORTH BAY AND A TENTH OF AN INCH SOUTH OF
THE GOLDEN GATE BRIDGE. NBM GUIDANCE DOES SHOW A 5-10% CHANCE OF
THUNDERSTORMS WEDNESDAY TO THURSDAY WITH THIS WEAK SYSTEM. AFTER
THIS SYSTEM PASSES, HIGH TEMPERATURES THURSDAY TO MONDAY WILL
GENERALLY BE IN THE UPPER 50S TO LOW 60S ALONG THE COAST AND 60S
ACROSS THE INTERIOR. RAIN ENTHUSIASTS WILL BE EXCITED FOR THE
BEGINNING OF APRIL AS A PARADE OF STORM SYSTEMS ENTER THE WEST COAST
FROM THE END OF MARCH THROUGH THE FIRST WEEK OF APRIL. MULTIPLE
ROUNDS OF RAIN ARE ANTICIPATED WITH THE FIRST ROUND LOOKING TO TAKE
PLACE SUNDAY INTO MONDAY. METEOGRAM GUIDANCE FROM THE ECMWF AND GFS
SUGGEST THAT THIS FIRST ROUND OF RAIN WILL BE LIGHTER THAN
ADDITIONAL STORMS MOVING IN MID NEXT WEEK (BEYOND THE END OF THIS
FORECAST PERIOD). IT IS STILL TOO FAR OUT FOR SPECIFIC TOTALS BUT
ENSEMBLE GUIDANCE REMAINS CONSISTENT IN THE IDEA THAT WE WILL SEE AT
LEAST ANOTHER 1-2 INCHES OF RAIN FROM THIS EVENT AS A WHOLE WITH
LOCALLY HIGHER TOTALS POSSIBLE IN FAVORED AREAS.
AVIATION
(06Z TAFS)
ISSUED AT 1027 PM PDT MON MAR 24 2025
CLEAR SKIES CONTINUE, ALLOWING FOR VFR CONDITIONS CURRENTLY. MODELS
SHOW AGREEMENT THAT VFR WILL PREVAIL THROUGH THE TAF PERIOD FOR MOST
OF THE TERMINALS. THERE IS A HINT FOR HAZE/FOG BETWEEN 12Z-16Z
OVERNIGHT, BUT CONFIDENCE IS LOW AT THIS MOMENT. WINDS WILL CONTINUE
TO REMAIN RELATIVELY LIGHT TO MODERATE THROUGH THE TAF PERIOD, BUT
WILL GRADUALLY TURN S/SE BY LATE TUESDAY AFTERNOON.
VICINITY OF SFO...VFR THROUGH THE TAF PERIOD WITH A SLIGHT CHANCE
FOR HAZE OVERNIGHT.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR THROUGH MOST OF THE TAF PERIOD WITH
LIGHT TO MODERATE WINDS. WINDS WILL TURN TO S/SE OVERNIGHT. THERE IS
A CHANCE FOR MVFR CONDITIONS OVER KMRY TUESDAY NIGHT, BUT THERE IS
UNCERTAINTY AS SOME MODELS SHOW VFR THROUGH THE TAF PERIOD.
MARINE
(TODAY THROUGH SUNDAY)
ISSUED AT 319 AM PDT TUE MAR 25 2025
NORTHERLY LIGHT TO GENTLE BREEZES CONTINUE THROUGH TUESDAY NIGHT
WITH WINDS TURNING SOUTHERLY AND BECOMING MODERATE TO FRESH BY MID
WEDNESDAY. SEAS WILL FLUX BETWEEN MODERATE AND ROUGH THROUGH
WEDNESDAY. CONDITIONS DETERIORATE THURSDAY WHEN A WEST TO
NORTHWEST BREEZES BECOME FRESH AND SEAS BECOME ROUGH. UNSETTLED
CONDITIONS CONTINUE THROUGH THE WEEKEND AND INTO THE NEXT WORK
WEEK AS STORM SYSTEMS MOVE THROUGH THE REGION.
BEACHES
ISSUED AT 829 PM PDT MON MAR 24 2025
A BEACH HAZARDS STATEMENT IS IN EFFECT THROUGH WEDNESDAY MORNING
FOR ALL PACIFIC COAST BEACHES. THE WARM CONDITIONS ON LAND WILL DO
NOTHING TO THE PACIFIC OCEAN THAT IS 51-57 DEGREES. IN ADDITION
TO THE COLD WATER SHOCK RISK THAT IS ALWAYS PRESENT, THERE WILL BE
AN INCREASED RISK FOR SNEAKER WAVES AND RIP CURRENTS. OBSERVE THE
OCEAN FOR 20 MINUTES BEFORE YOU PICK A SPOT ON THE BEACH, STAY
OFF OF JETTIES AND ROCKS, KEEP PETS ON A LEASH, WEAR A LIFE
JACKET, AND NEVER TURN YOUR BACK ON THE OCEAN!
CLIMATE
ISSUED AT 410 PM PDT FRI MAR 21 2025
RECORD HIGH TEMPERATURES AT THE LONG TERM STATIONS FOR MARCH 24TH
AND 25TH.
STATION MARCH 24TH MARCH 25TH
SANTA ROSA 91F IN 1926 88F IN 1952
KENTFIELD 88F IN 1926 84F IN 1997, 1930
NAPA 86F IN 1926 85F IN 1988, 1970
RICHMOND 78F IN 1951 83F IN 1952
LIVERMORE 82F IN 2022, 2014 82F IN 1997
SAN FRANCISCO 82F IN 1926 83F IN 1952
SFO AIRPORT 78F IN 1970 85F IN 1952
REDWOOD CITY 83F IN 1970 84F IN 1952
HALF MOON BAY 73F IN 1941 72F IN 1969, 1947
OAKLAND DOWNTOWN 75F IN 1997 80F IN 1988
SAN JOSE 84F IN 1926 84F IN 1930
SALINAS AIRPORT 84F IN 1951 85F IN 1988
KING CITY 87F IN 1951 87F IN 1988, 1930
MTR WATCHES/WARNINGS/ADVISORIES
CA...BEACH HAZARDS STATEMENT THROUGH WEDNESDAY MORNING FOR CAZ006-505-
509-529-530.
PZ...NONE.
SHORT TERM...KENNEDY
LONG TERM....KENNEDY
AVIATION...SO
MARINE...KR
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