405
FXUS66 KMTR 151945
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1245 PM PDT SAT MAR 15 2025
..NEW SYNOPSIS, SHORT TERM, LONG TERM
SYNOPSIS
ISSUED AT 1236 PM PDT SAT MAR 15 2025
DRY TODAY GOING INTO SUNDAY WITH WIDESPREAD RAIN EXPECTED FOR THE
LATTER HALF OF SUNDAY INTO MONDAY MORNING. GUSTY WINDS IN THE
NORTH BAY WITH THE PASSAGE OF THE INITIAL COLD FRONT SUNDAY
AFTERNOON. ISOLATED SHOWERS MONDAY, THE DRIER AND CLEAR TUESDAY
GOING INTO WEDNESDAY. ADDITIONAL CHANCES FOR LIGHT RAINFALL
WEDNESDAY NIGHT GOING INTO THE WEEKEND, BUT HEAVIER RAINFALL WILL
LIKELY STAY NORTH.
SHORT TERM
(THIS EVENING THROUGH SUNDAY)
ISSUED AT 1236 PM PDT SAT MAR 15 2025
PRETTY NICE LITTLE SATURDAY IF YOU ASK ME. CURRENT SATELLITE SHOWING
SOME LIGHT CLOUD COVER OVER THE REGION, THICKER UP IN NORTHERN
SONOMA COUNTY WHERE THE BETTER MOISTURE EXISTS THROUGH THE
ATMOSPHERIC COLUMN. ELSEWHERE, THERE IS VERY PRONOUNCED DRY SLOT
FROM ABOUT 850-700 MB, EVIDENT VIA THE 12Z OAK SOUNDING. THIS WILL
FAIRLY EFFECTIVELY KEEP THE LID ON THINGS TODAY. THERE WERE A FEW
LIGHT SHOWERS OVER THE OCEAN THIS MORNING, BUT THEY HAVE SINCE
DISSIPATED THANKS TO THIS DRY STABLE LAYER. SOME DIURNALLY DRIVEN
CUMULUS OVER THE TERRAIN EARLY THIS AFTERNOON, BUT NOTHING MUCH IS
EXPECTED OF THEM. SIMILAR WEATHER STORY FOR THE EARLY HALF OF
SUNDAY. HOWEVER, WE WILL BE UNDERGOING AIRMASS MODIFICATION UNDER A
SOUTHERLY FLOW REGIME AHEAD OF THE NEXT STORM SYSTEM. MOISTURE WILL
GRADUALLY INCREASE THROUGH THE DAY WITH SHOWERS BEGINNING IN THE
NORTH BAY BY MIDMORNING. THE MAIN COLD FRONT LAGS BEHIND A BIT, AND
LIKELY WON'T MOVE THROUGH THE REGION UNTIL THE EVENING HOURS JUST
BEFORE SUNSET. SO FOR THE REST OF THE REGION OUTSIDE OF THE NORTH
BAY, SHOWERS ARE LIKELY TO HOLD OFF UNTIL AROUND SUNSET. THE MAIN
BAND OF SHOWERS SHOULD COMPLETELY MOVE THROUGH THE AREA OVERNIGHT
SUNDAY NIGHT. WE'RE TALKING A PURELY BENEFICIAL STORM WITH RAINFALL
TOTALS AROUND 0.50-1.00". LOCALLY HIGHER AMOUNTS UP TO 1.5" IN
NORTHERN SONOMA AND NAPA COUNTIES. I CALL THEM "SONAPA" SOMETIMES ON
ACCIDENT WHEN TRYING TO REFERENCE THEM BOTH. MAYBE IT'LL CATCH ON
INSTEAD OF "NORTH BAY"? "NAPOMA" PERHAPS? "SONAPIN" IF MARIN IS TO
BE INCLUDED? I DIGRESS. IN TERMS OF WIND POTENTIAL, WE HAVE
ISSUED A WIND ADVISORY FOR THE MARIN AND SONOMA COASTAL RANGES AND
THE NORTH BAY INTERIOR MOUNTAINS ZONE. SW WINDS GUSTING TO 45-55
MPH WILL BE LIKELY IN THE HIGHER HILLS WITHIN THE ADVISORY AREA.
OTHERWISE, LOCATIONS IN THE NORTH BAY VALLEYS SHOULD EXPECT GUSTS
TO 35-40 MPH. THERE IS SOME LIMITED CONVECTIVE POTENTIAL ON MONDAY
IN THE POST- FRONTAL ENVIRONMENT, BUT I'LL LEAVE THAT TO THE LONG
TERM BELOW.
LONG TERM
(SUNDAY NIGHT THROUGH NEXT FRIDAY)
ISSUED AT 1236 PM PDT SAT MAR 15 2025
THE SURFACE LOW APPROACHES THE COAST ON MONDAY AS A SECONDARY COLD
FRONT ALOFT PUSHES THROUGH THE REGION. THIS WILL ACT AS AN
ADDITIONAL SOURCE OF LIFT AS WELL AS DECREASING TEMPERATURES ALOFT,
RESULTING IN 100-300 J/KG OF SURFACE BASED CAPE TO WORK WITH. VERY
SLIM CHANCE FOR THUNDER, BUT WE WILL LIKELY SEE ISOLATED CONVECTIVE
SHOWERS THROUGH MONDAY. MUCH LIKE WE SAW THESE PAST FEW DAYS WHERE
THE TIMELINE HAS BEEN SUN, SUN, CLOUD?, RAIN! FEAT. LIL' HAIL,
THEN SUN AGAIN. ANY HAIL THAT DECIDES TO MAKE A CAMEO WILL BE
RICE-SIZED, PEAS AT BEST. THE SURFACE LOW COMES ASHORE MONDAY
EVENING, AND THE SHOWER ACTIVITY WILL LARGELY COME TO AND END BY
SUNSET. WITH SKIES CLEARING BEHIND THE LOW AND COLDER AIR IN
PLACE, EXPECT CHILLY OVERNIGHT TEMPS BEGINNING MONDAY
NIGHT/TUESDAY MORNING. FROST/FREEZE PRODUCTS MAY BE NEEDED FOR
INLAND AREAS INTO MIDWEEK.
LOOKING ON THE DRIER SIDE TUESDAY GOING INTO WEDNESDAY BETWEEN
TROUGHS. WE'RE SET UP FOR ANOTHER WEAK TROUGH TO COME THROUGH
WEDNESDAY EVENING, BRINGING LIGHT RAIN CHANCES AGAIN, BUT MAINLY
NORTH OF MONTEREY BAY. THE OVERALL PATTERN REMAINS ACTIVE GOING INTO
THE WEEKEND WITH SEVERAL SYSTEMS PROGGED TO MOVE THROUGH THE
NORTHEAST PACIFIC. HOWEVER, THE DEGREE OF RIDGING TO OUR SOUTH WILL
PLAY A ROLE IN HOW FAR NORTH OR SOUTH THESE SYSTEMS CAUSE IMPACTS.
AS OF THIS ISSUANCE, CONFIDENCE IS MODERATE THAT WE MAY SEE SOME
LIGHT RAIN INTO NEXT WEEKEND, BUT THE BULK OF THE MOISTURE WILL
REMAIN WELL TO OUR NORTH. BEYOND THAT, THERE IS INCREASING
CONFIDENCE IN CLEAR CONDITIONS AND WARM TEMPERATURES LOOKING JUST
BEYOND OUR 7 DAY OUTLOOK INTO THE BEGINNING OF THE LAST FULL WEEK OF
THE MONTH.
AVIATION
(18Z TAFS)
ISSUED AT 1039 AM PDT SAT MAR 15 2025
A MIX OF SCT/BKN LOW CLOUDS ACROSS THE NORTH BAY AND REDUCED
VISIBILITIES CONTINUE LATE THIS MORNING ACROSS MOST TAF SITES.
HOWEVER, CONDITIONS ARE FORECAST TO IMPROVE TO VFR THROUGH MUCH OF
THE DAY WITH LINGERING MID-LEVEL CLOUDS LIKELY TO PERSIST ACROSS THE
NORTH BAY. AN APPROACHING COLD FRONT WILL BRING SOME LIGHT RAIN BACK
TO THE REGION ON SUNDAY, MAINLY ACROSS THE NORTH BAY DURING THE
CURRENT TAF PERIOD. LOWERING CEILINGS ARE ALSO FORECAST FOR THE BAY
AREA TERMINALS SUNDAY MORNING.
VICINITY OF SFO...GENTLE WESTERLY WINDS ARE FORECAST BY THIS
AFTERNOON AND THEN ARE FORECAST TO BACK TO SOUTHERLY BREEZE BY LATE
TONIGHT. VFR FORECAST TO PERSIST THROUGH MUCH OF THE TAF PERIOD
BECOMING MVFR AROUND 17Z SUNDAY.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR. DRAINAGE FLOW THROUGH LATE MORNING
WILL GRADUALLY BECOME SCATTERED MID-LEVEL CLOUDS AND A GENTLE
ONSHORE BREEZE. LATE IN THE TAF PERIOD, THE DIURNAL DRAINAGE FLOW
SHOULD RETURN, BUT DRIER AIR WILL LIKELY KEEP VFR CONDITIONS
ENTRENCHED THROUGH THE NIGHT AND INTO SUNDAY MORNING.
MARINE
(TODAY THROUGH THURSDAY)
ISSUED AT 1039 AM PDT SAT MAR 15 2025
HIGH PRESSURE OVER THE EASTERN PACIFIC WILL CAUSE WINDS TO
DIMINISH TO A GENTLE SOUTHWEST BREEZE TODAY, ALLOWING ROUGH SEAS
TO GRADUALLY SUBSIDE. AN APPROACHING COLD FRONT WILL CAUSE WINDS
TO INCREASE TO A STRONG BREEZE SUNDAY AFTERNOON WITH POTENTIAL
GALE FORCE GUSTS IN THE NORTHERN WATERS. THESE WINDS WILL GENERATE
MORE ROUGH SEAS LASTING THROUGH MONDAY.
MTR WATCHES/WARNINGS/ADVISORIES
CA...WIND ADVISORY FROM 11 AM TO 11 PM PDT SUNDAY FOR CAZ502>504.
PZ...SMALL CRAFT ADVISORY FROM 10 AM SUNDAY TO 3 AM PDT MONDAY FOR
MRY BAY-SF BAY N OF BAY BRIDGE.
SMALL CRAFT ADVISORY UNTIL 9 AM PDT SUNDAY FOR PT ARENA TO PT
REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM.
GALE WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR PT
ARENA TO PT REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM-PT
REYES TO PIGEON PT 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 AM TO 9 AM PDT SUNDAY FOR PT REYES
TO PIGEON PT 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR PIGEON PT
TO PT PINOS 0-10 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY FROM 9 AM SUNDAY TO 3 AM PDT MONDAY FOR
PIGEON PT TO PT PINOS 0-10 NM-PIGEON PT TO PT PINOS 10-60
NM.
SMALL CRAFT ADVISORY FROM 3 PM SUNDAY TO 3 AM PDT MONDAY FOR PT
PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR PIGEON PT
TO PT PINOS 10-60 NM.
SHORT TERM...BEHRINGER
LONG TERM....BEHRINGER
AVIATION...RGASS
MARINE...RGASS
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO
FOLLOW US ON FACEBOOK, X, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
X.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page