792
FXUS66 KMTR 131925
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1225 PM PDT THU MAR 13 2025
..NEW AVIATION, MARINE
SYNOPSIS
ISSUED AT 1251 AM PDT THU MAR 13 2025
SCATTERED SHOWERS AND A CHANCE OF THUNDERSTORMS CONTINUE INTO THE
MORNING BEFORE DIMINISHING THROUGH THE AFTERNOON. ANOTHER SYSTEM
ARRIVES FRIDAY, WITH UNSETTLED WEATHER THROUGH THE NEXT WEEK.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 1251 AM PDT THU MAR 13 2025
THE MAIN FRONTAL RAIN BAND HAS MOVED THROUGH THE REGION AND INTO THE
CENTRAL VALLEY AND SOUTHERN CALIFORNIA, LEAVING A PATCHWORK OF
SCATTERED SHOWERS IN ITS WAKE. THESE SHOWERS ARE EXPECTED TO
CONTINUE THROUGH THE MORNING HOURS BEFORE THE COVERAGE DECREASES IN
THE AFTERNOON. WITH THE COLD AIR ADVECTION ALLOWING LAPSE RATES TO
INCREASE, THE CHANCE FOR SOME OF THOSE SHOWERS TO TURN INTO
THUNDERSTORMS CONTINUES. THE STORM PREDICTION CENTER MAINTAINS A
GENERAL RISK OF THUNDERSTORMS THROUGH THE DAY TODAY, WITH A 20-30%
PROBABILITY OF THUNDERSTORMS THROUGH THE AFTERNOON HOURS. LOCALLY
HEAVY DOWNPOURS AND SMALL HAIL WILL BE THE MAIN THREATS. REMEMBER,
WHEN THUNDER ROARS, GO INDOORS! OR, SEE A FLASH, DASH INSIDE!
THE COLD AIR WILL ALSO ALLOW A CHANCE FOR SNOW ACROSS THE HIGHER
ELEVATIONS, WITH SNOW LEVELS DESCENDING TO AROUND 3000 FEET. CAMERAS
AT CHEWS RIDGE AND PALO ESCRITO CAPTURED SNOWFALL AT BOTH PEAKS
BEFORE SUNRISE YESTERDAY, AND CONDITIONS REMAIN FAVORABLE FOR
CONTINUING SNOWFALL IN THE HIGHER ELEVATIONS THROUGH THE MORNING.
CHILLY TEMPERATURES CONTINUE TODAY WITH MANY AREAS WITHIN THE LOWER
ELEVATIONS SEEING HIGH TEMPERATURES AROUND 8 TO 15 DEGREES BELOW
SEASONAL AVERAGES. THE INLAND VALLEYS REACH THE MID 50S, THE PACIFIC
COAST AROUND THE LOW 50S, AND PERHAPS INTO THE 40S OR THE UPPER 30S
ACROSS THE HIGHER ELEVATIONS. BREEZY NORTHWESTERLY WINDS WILL
DEVELOP THIS AFTERNOON, ALTHOUGH WE ARE NOT EXPECTING CONDITIONS
THAT WOULD REQUIRE A WIND ADVISORY TODAY, AS GUSTS GENERALLY REACH
20 TO 25 MILES PER HOUR. THE WINDS DO SHIFT TOWARDS A MORE SOUTHERLY
DIRECTION THIS EVENING, THE FIRST HARBINGER OF ANOTHER ROUND OF
STORMS.
LONG TERM
(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 1251 AM PDT THU MAR 13 2025
THE ACTIVE WEATHER PATTERN CONTINUES THROUGH THE WEEK AS A SERIES OF
UPPER LEVEL TROUGHS IMPACTS THE REGION. THE NEXT SYSTEM IS EXPECTED
ON FRIDAY AS ANOTHER FRONTAL SYSTEM ARRIVES AFTER MIDNIGHT AND MOVES
THROUGH THE REGION THROUGH FRIDAY MORNING, WITH LINGERING SHOWERS
THROUGH THE REST OF THE DAY. THIS SYSTEM IS NOT EXPECTED TO BE AS
INTENSE AS THE ONE THAT CAME THROUGH YESTERDAY, WITH RAIN TOTALS
GENERALLY 0.25-0.5" IN THE VALLEYS AND UP TO 1" ACROSS THE HIGHER
ELEVATIONS AND WIND GUSTS REACHING 30-35 MILES PER HOUR ACROSS THE
RIDGELINES.
SATURDAY SHOULD BE A BREAK FOR MOST PEOPLE, WITH THE ONLY RAIN
ACCUMULATIONS BEING A FEW HUNDREDTHS OF AN INCH IN THE SONOMA
COASTAL RANGES, BEFORE A SECOND SYSTEM COMES THROUGH THE REGION ON
SUNDAY INTO MONDAY MORNING. THE NORTH BAY LOOKS TO SEE MORE RAINFALL
FROM THIS SYSTEM WITH THE CURRENT FORECAST CALLING FOR 0.5-1" IN THE
VALLEYS, WHILE THE BAY AREA AND MONTEREY BAY REGIONS ARE ANTICIPATED
TO SEE 0.25-0.5" ACROSS THE LOWER ELEVATIONS AND UP TO 0.75" IN THE
COASTAL RANGES, WHILE LOCATIONS IN THE SOUTHERN SALINAS VALLEY MIGHT
NOT BREAK A TENTH OF AN INCH OF RAIN. THERE'S STILL SOME TIME TO
REFINE THE RAINFALL TOTALS FROM THIS SYSTEM, SO KEEP AN EYE ON THE
FORECAST UPDATES. ENSEMBLE MODEL CLUSTER ANALYSIS SUGGESTS THAT
RELATIVELY SUBTLE CHANGES IN THE POSITIONING OF THE TROUGH COULD
SWING RAINFALL TOTALS ACROSS THE NORTH BAY BY AS MUCH AS AN INCH.
BEHIND THIS SYSTEM, ENSEMBLE MODELS ARE PICKING UP ON ANOTHER UPPER
LEVEL TROUGH TOWARDS THE LATTER PART OF NEXT WEEK, BUT IT'S TOO
EARLY TO PINPOINT ANY SPECIFIC IMPACTS.
TEMPERATURES REMAIN RATHER CHILLY THROUGH THE WEEK, SLOWLY WARMING
THROUGH SUNDAY WHEN THE INTERIOR VALLEYS REACH THE SEASONAL AVERAGE
HIGHS WITHIN THE MIDDLE TO UPPER 60S BEFORE DROPPING BACK DOWN ON
MONDAY, AND WARMING BACK AGAIN INTO THE UPCOMING WEDNESDAY AND
THURSDAY WHEN THE INLAND VALLEYS AGAIN REACH THE MID TO UPPER 60S.
THE NORTH BAY SEES A MORE MUTED RISE IN TEMPERATURES WITH HIGHS IN
THE INLAND VALLEYS REACHING THE UPPER 50S TO LOWER 60S THIS WEEKEND,
WHILE COASTAL AREAS REMAIN IN THE MIDDLE 50S TO NEAR 60
THROUGHOUT.
AVIATION
(18Z TAFS)
ISSUED AT 1223 PM PDT THU MAR 13 2025
SPOTTY THUNDERSTORM CHANCES DECREASE INTO THE AFTERNOON WITH SOME
LINGERING SHOWERS CHANCES LASTING INTO THE LATE AFTERNOON. BREEZY TO
GUSTY WEST WINDS LAST INTO THE EVENING BEFORE REDUCING. SOUTHERLY
WINDS INCREASE AGAIN INTO THE LATE NIGHT AS THE NEXT RAIN SYSTEM
APPROACHES. STRONG AND GUSTY WINDS ARE EXPECTED THROUGH MUCH OF
FRIDAY MORNING WITH MVFR CIGS AND MODERATE RAIN RATES CALLING FOR
REDUCTIONS IN VISIBILITIES. WINDS TURN WESTERLY AS RAIN BECOMES
SPOTTY INTO LATE FRIDAY MORNING. WINDS REMAIN BREEZY BEYOND THE TAF
PERIOD.
VICINITY OF SFO...EXPECT SCATTERED SHOWERS WITH SLIGHT CHANCES FOR
ISOLATED THUNDERSTORMS THIS AFTERNOON WITH OVERALL RAIN CHANCES
EXITING BY THE MID TO LATE AFTERNOON. EXPECT BREEZY WEST WINDS IN
THE MID AFTERNOON AND INTO THE EVENING BEFORE REDUCING. SHOWER
ACTIVITY ARRIVES INTO THE NIGHT AS WINDS TURN MORE SOUTHERLY. THESE
SOUTH WINDS BECOME THROUGH IN THE LATE NIGHT AS MORE PERSISTENT RAIN
ARRIVES ALONG WITH MVFR CIGS. SHOWERS BECOME MORE SCATTERED LATE
FRIDAY MORNING AS CIGS LIFT AND WINDS TURN WEST AND REMAIN STRONG
AND GUSTY.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...SHOWER AND STORM CHANCES EXIT THIS
AFTERNOON, WITH MODERATE TO BREEZY WINDS LASTING INTO THE LATE
EVENING, BEFORE BECOMING LIGHT. STRONGER AND GUSTY SOUTH WINDS
ARRIVE IN THE LATE NIGHT WITH MODERATE RAIN AND MVFR CIGS. THESE
WINDS INCREASE FURTHER INTO EARLY FRIDAY. RAIN CHANCES REDUCE AS
CIGS LIFT IN THE LATE MORNING. WINDS WILL TURN WEST AND REDUCE
SLIGHTLY BEFORE FRIDAY AFTERNOON.
MARINE
(TONIGHT THROUGH NEXT TUESDAY)
ISSUED AT 1223 PM PDT THU MAR 13 2025
BREEZY CONDITIONS AND ELEVATED SEAS CONTINUE ACROSS THE WATERS
CONTINUE, CAUSING HAZARDOUS CONDITIONS FOR SMALL CRAFT. SCATTERED
SHOWERS CONTINUE INTO THE AFTERNOON WITH CHANCES FOR
THUNDERSTORMS AND ASSOCIATED STRONGER GUSTS. SEAS WILL REMAIN
ROUGH INTO NEXT WEEK AS A SERIES OF STORMS MOVES THROUGH.
MTR WATCHES/WARNINGS/ADVISORIES
CA...FROST ADVISORY FROM 11 PM THIS EVENING TO 9 AM PDT FRIDAY FOR
CAZ516>518.
PZ...SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR MRY BAY-
PIGEON PT TO PT PINOS 0-10 NM-PT REYES TO PIGEON PT 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 AM TO 9 PM PDT FRIDAY FOR MRY BAY-
PIGEON PT TO PT PINOS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 9 PM PDT FRIDAY FOR PIGEON PT TO PT
PINOS 10-60 NM-PT ARENA TO PT REYES 0-10 NM-PT ARENA TO PT
REYES 10-60 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SHORT TERM...DIALH
LONG TERM....DIALH
AVIATION...MURDOCK
MARINE...MURDOCK
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