884
FXUS66 KMTR 212042
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
142 PM PDT WED OCT 21 2026
..NEW SHORT TERM, LONG TERM
KEY MESSAGES
UPDATED AT 141 PM PDT WED OCT 21 2026
- RAIN SHOWERS EXPECTED THROUGH THURSDAY AFTERNOON
- THUNDERSTORMS POSSIBLE THIS AFTERNOON INTO THURSDAY MORNING
ACROSS NORTH CENTRAL COAST
- A WARMING AND DRYING TREND EXPECTED FOR THE UPCOMING WEEKEND
AND INTO EARLY NEXT WEEK
SHORT TERM
ISSUED AT 141 PM PDT WED OCT 21 2026
(THIS EVENING THROUGH THURSDAY NIGHT)
THE GREATEST POTENTIAL FOR THUNDERSTORMS WILL BE THIS AFTERNOON AND
EVENING AS UP TO 400-800 J/KG OF MUCAPE (MOST UNSTABLE CONVECTIVE
AVAILABLE POTENTIAL ENERGY) SPREADS ACROSS THE NORTH CENTRAL COAST.
WE'VE ALREADY SEEN LIGHTNING STRIKES AROUND THE WATSONVILLE AREA
WITH ONGOING CONVECTION OFF OF THE COAST. THE MOST LIKELY TIMING OF
THIS WILL BE BETWEEN NOW AND 10 PM THIS EVENING BEFORE THE CUT-OFF
LOW PRESSURE SYSTEM BEGINS TO PUSH ONSHORE OVER CENTRAL/SOUTHERN
CALIFORNIA AND WE LOSE THE UPPER LEVEL INSTABILITY ALOFT. THE SPC
ISSUED A 2-4% TORNADO PROBABILITY FOR THE BIG SUR COASTLINE, THEREBY
INDICATING INCREASED POTENTIAL FOR SOME LOW-TOPPED SUPERCELLS. IF
THE OFFSHORE CONVECTION MOVES INLAND WITH ROTATION, THERE IS THE
POTENTIAL FOR A TORNADO.
FARTHER NORTH ACROSS THE BAY AREA AND NORTH BAY, CANNOT RULE OUT AN
ISOLATED THUNDERSTORM OR TWO. RAINFALL ACROSS THIS REGION IS ALSO
EXPECTED TO BE MUCH LIGHTER WITH THE POSITION OF THE LOW PRESSURE
SYSTEM FARTHER TO THE SOUTH. ACROSS THE NORTH BAY AND BAY AREA,
EXPECTING GENERALLY <0.30" WITH GENERALLY 0.25-0.75" ACROSS THE
NORTH CENTRAL COAST, AND 0.75-1.25" IN THE SANTA CRUZ MOUNTAINS AND
SANTA LUCIA RANGE THROUGH THURSDAY NIGHT. ANY HEAVIER RAIN SHOWER
AND/OR THUNDERSTORM WILL LIKELY PRODUCE BRIEF HEAVY DOWNPOURS ADDING
TO THE RAINFALL AMOUNTS.
IF SEVERE WEATHER DOES DEVELOP, HERE ARE SOME SAFETY REMINDERS:
* HAVE MULTIPLE WAYS TO RECEIVE EMERGENCY ALERTS (I.E. NOAA WEATHER
RADIO, FOLLOW NWS BAY AREA ON SOCIAL MEDIA, AND/OR ENSURING YOUR
PHONE'S EMERGENCY ALERT SYSTEM IS ON)
* MOVE TO AN INTERIOR ROOM AWAY FROM WINDOWS, IF A WATERSPOUT MAKES
LANDFALL
* HAVE AN EMERGENCY ACTION PLAN READY IF YOU LIVE DOWNSLOPE OF
WILDFIRE BURN SCARS
* AVOID FLOODED ROADS. TURN AROUND, DON'T DROWN!
POST FRONTAL RAIN SHOWERS ARE FORECAST TO LINGER INTO EARLY THURSDAY
AFTERNOON WITH LESS THAN A 15% PROBABILITY FOR THUNDERSTORMS
CONTINUING THROUGH THE MORNING. BY THE THURSDAY EVENING, DRYING
CONDITIONS ARE FORECAST TO RETURN TO THE REGION.
LONG TERM
ISSUED AT 141 PM PDT WED OCT 21 2026
(FRIDAY THROUGH NEXT TUESDAY)
AS THE UPPER LEVEL THROUGH PUSHES FARTHER INLAND, PERIODS OF
MODERATE NORTHERLY WINDS ARE LIKELY ACROSS THE NORTH BAY INTERIOR
MOUNTAINS. WINDS ACROSS THIS REGION HAVE THE POTENTIAL TO BE 15-25
MPH WITH GUSTS UP TO 45 MPH FRIDAY NIGHT INTO SATURDAY MORNING.
A GRADUAL WARMING AND DRYING TREND WILL PERSIST ACROSS THE REGION AS
WEAK HIGH PRESSURE BUILDS IN FROM THE EASTERN PACIFIC. LOW-LYING
AREAS ALONG THE SAN FRANCISCO BAY, SAN PABLO BAY, AND ALONG THE
COAST ARE LIKELY TO SEE MINOR COASTAL FLOODING OVER THE WEEKEND
DURING PEAK HIGH TIDES. THIS IS LIKELY TO PERSIST INTO AT LEAST THE
MIDDLE OF THE UPCOMING WEEK.
WEATHERWISE, THERE IS A GREAT DEAL OF UNCERTAINTY BEYOND MONDAY AS
THE WEAK RIDGING BEGINS TO BREAK DOWN. THERE IS THE SIGNAL FOR
ADDITIONAL TROUGHING BY LATE NEXT WEEK BRINGING COOLER AND UNSETTLED
WEATHER CONDITIONS TO THE REGION.
AVIATION
(18Z TAFS)
ISSUED AT 1049 AM PDT WED OCT 21 2026
CURRENTLY VFR WITH CLOUDS AND RAIN SHOWERS PUSHING IN FROM THE
SOUTH. THE BEST CHANCES FOR THUNDERSTORMS ARE FOR THE MONTEREY BAY
TERMINALS THIS AFTERNOON AND THIS EVENING, 22Z TO 02Z. ELSEWHERE,
RAIN SHOWERS ARE EXPECTED THROUGH THE TAF PERIOD, SPREADING FROM
SOUTH TO NORTH. THE BEST CHANCES FOR RAIN SHOWERS TO OCCUR AT A
TERMINAL WILL BE THIS AFTERNOON AND THIS EVENING AS COVERAGE AND
INTENSITY INCREASES; HOWEVER, CHANCES LINGER THROUGH THE TAF PERIOD
WITH WRAP AROUND RAIN SHOWERS EXPECTED OVERNIGHT INTO TOMORROW
MORNING. WINDS WILL BE LIGHT AND DIURNAL EXCEPT WHEN RAIN
SHOWER/THUNDERSTORM DRIVEN. LOW CONFIDENCE ON SUB-VFR CEILINGS
DEVELOPING OVERNIGHT; HOWEVER, SUB-VFR CEILINGS AND VISIBILITIES CAN
BE EXPECTED BRIEFLY IF A RAIN SHOWER PASSES DIRECTLY OVER A
TERMINAL.
VICINITY OF SFO...CURRENTLY VFR WITH NORTHWESTERLY FLOW. CLOUDS WILL
CONTINUE TO LOWER THROUGH THE MORNING WITH RAIN SHOWERS EXPECTED BY
THIS AFTERNOON. THE BEST CHANCES FOR RAIN SHOWERS DIRECTLY AT THE
TERMINAL TODAY ARE BETWEEN 22Z AND 04Z WITH WRAP AROUND RAIN SHOWERS
CONTINUING THROUGH THE END OF THE TAF PERIOD. CONDITIONS MAY IMPROVE
TOWARDS THE TAIL END OF THE TAF PERIOD AT OR AFTER 20Z; HOWEVER,
ANOTHER CHANCE OF RAIN SHOWERS IS EXPECTED DURING THIS TIME AS
THE UPPER-LEVEL LOW PULLS EAST.
SFO BRIDGE APPROACH...RELATIVELY HIGHER CHANCE FOR THUNDERSTORMS;
HOWEVER, THE BEST CHANCES REMAIN SOUTH OF SJC. CLOUDS WILL LOWER AND
RAIN SHOWERS WILL OCCUR SOONER THAN SFO. CLOUDS AT OR BELOW FL070
ARE EXPECTED THROUGH THE TAF PERIOD; HOWEVER, CONDITIONS MAY BRIEFLY
IMPROVE BETWEEN RAIN SHOWERS.
MONTEREY BAY TERMINALS...CURRENTLY VFR WITH SOUTHEASTERLY FLOW AT
BOTH TERMINALS AND RAIN BEGINNING TO BE OBSERVED AT MRY. THERE IS A
CHANCE FOR THUNDERSTORMS TODAY WITH THE BEST CHANCES BEING BETWEEN
22Z AND 02Z. RAIN SHOWERS WILL INCREASE IN COVERAGE AND INTENSITY
THIS EVENING. WRAP AROUND RAIN SHOWERS ARE EXPECTED OVERNIGHT AND
INTO TOMORROW MORNING, LIKELY LESS IN COVERAGE AND INTENSITY. WINDS
WILL BE LIGHT AND DIURNAL EXCEPT WHEN RAIN SHOWER/THUNDERSTORM
DRIVEN.
MARINE
(TODAY THROUGH MONDAY)
ISSUED AT 939 AM PDT WED OCT 21 2026
THERE IS A CHANCE FOR THUNDERSTORMS TODAY, ESPECIALLY SOUTH OF
PIGEON POINT. RAIN SHOWERS AND THUNDERSTORMS WILL BE CAPABLE OF
PRODUCING LOCAL GALE FORCE WIND GUSTS, ROUGH SEAS, HEAVY RAINFALL
WITH REDUCED VISIBILITY, AND WATERSPOUTS. GENTLE VARIABLE BREEZES
WILL PREVAIL TODAY. MODERATE TO FRESH NORTHERLY BREEZES WILL
PREVAIL THURSDAY THROUGH SUNDAY WITH LOCALLY STRONG TO NEAR GALE
BREEZES ACROSS THE OUTER WATERS THURSDAY THROUGH SATURDAY.
MODERATE SEAS BUILD TO BECOME ROUGH ACROSS THE OUTER WATERS
FRIDAY.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 9 PM THURSDAY TO 9 AM PDT FRIDAY FOR
PIGEON PT TO PT PINOS 10-60 NM-PT ARENA TO PT REYES 0-10 NM.
SMALL CRAFT ADVISORY FROM 3 PM THURSDAY TO 9 AM PDT FRIDAY FOR
PT ARENA TO PT REYES 10-60 NM.
SHORT TERM...RGASS
LONG TERM....RGASS
AVIATION...SARMENT
MARINE...SARMENT
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