671
FXUS66 KMTR 061940
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1240 PM PDT MON APR 6 2026
..NEW SHORT TERM, LONG TERM
KEY MESSAGES
UPDATED AT 1237 PM PDT MON APR 6 2026
- COOLER SEASONAL TO SLIGHTLY BELOW NORMAL TEMPERATURES THIS WEEK
- BENEFICIAL RAIN ARRIVES MIDWEEK AND LASTS INTO THE WEEKEND
- SLIGHT CHANCES FOR THUNDERSTORMS THURSDAY AND FRIDAY AFTERNOON
SHORT TERM
ISSUED AT 1237 PM PDT MON APR 6 2026
(THIS EVENING THROUGH TUESDAY)
THE MARINE LAYER REDEVELOPED OVERNIGHT WITH WIDESPREAD STRATUS
OBSERVED ACROSS THE BAY AREA AND CENTRAL COAST DUE TO A WEAK
SHORTWAVE TROUGH MOVING INTO CALIFORNIA. WE ARE STILL LOOKING AT
COOLER TEMPERATURES TODAY WITH HIGHS IN THE LOW TO MID 70S ACROSS
THE INTERIOR AND 60S CLOSER TO THE COAST. LIGHT, ONSHORE WINDS
CONTINUE WITH LOCALLY BREEZIER CONDITIONS ACROSS THE HIGHER
ELEVATIONS AND MOUNTAIN GAPS/PASSES. WIDESPREAD STRATUS IS EXPECTED
AGAIN TONIGHT WITH THE MARINE LAYER DEEPENING TO AROUND 1500 FT.
MOST OF THE BAY AREA AND COASTAL CENTRAL COAST CAN EXPECT TO WAKE UP
TO OVERCAST CONDITIONS AGAIN WITH PATCHY FOG POSSIBLE IN THE NORTH
BAY AND SOUTH BAY VALLEYS. CLEARING TIMES TOMORROW WILL BE SIMILAR
TO TODAY WITH STRATUS COVERAGE GRADUALLY DISSIPATING OVER THE COURSE
OF THE MORNING. HIGH TEMPERATURES LINGER IN THE 70S ACROSS THE
INTERIOR AND 60S ALONG THE COASTLINE AGAIN ON TUESDAY. SHORTWAVE
RIDGING BRIEFLY BUILDS IN DURING THE DAY ON TUESDAY BEFORE THE RIDGE
QUICKLY PROGRESSES EASTWARD WEDNESDAY. STRATUS RETURNS TUESDAY NIGHT
BUT SHORTWAVE RIDGING WILL START TO COMPRESS THE MARINE LAYER AND
KEEP STRATUS CONFINED CLOSER TO THE COAST.
LONG TERM
ISSUED AT 1237 PM PDT MON APR 6 2026
(TUESDAY NIGHT THROUGH NEXT SUNDAY)
BRIEF SHORTWAVE RIDGING TUESDAY INTO WEDNESDAY WILL ALLOW
TEMPERATURES TO WARM SLIGHTLY ON WEDNESDAY BUT ONLY BY A FEW
DEGREES. HIGH TEMPERATURES WILL BE IN THE MID TO UPPER 70S ACROSS
THE INTERIOR, LOW 80S ACROSS THE INTERIOR CENTRAL COAST, AND IN THE
60S ALONG THE COAST. THIS WILL BE SHORT LIVED AS OUR PROMISED COOL
DOWN TRULY BEGINS THURSDAY AND CONTINUES INTO THE WEEKEND. A DEEP
UPPER LEVEL CUT-OFF LOW WILL APPROACH THE WEST COAST ON WEDNESDAY
AND WILL PUSH TUESDAY'S SHORTWAVE RIDGE EASTWARD. THIS LOW PRESSURE
SYSTEM IS A COLD CORE LOW FROM THE GULF OF ALASKA AND IS BRINGING A
COOLER AIR MASS (850 MB TEMPERATURES AROUND 6-8C) WITH IT. THE MEAN
850MB TEMPERATURE FOR EARLY TO MID APRIL IS AROUND 7-8C SO THIS
COLDER AIR MASS IS REALLY ONLY BRINGING US BACK TO MORE SEASONAL
TEMPERATURES. WE DO CONTINUE TO SEE COLDER AIR BEING ADVECTED IN
OVER THE WEEKEND WITH 850 MB TEMPERATURES DROPPING TO AROUND 0-1C.
THIS WOULD BE AROUND THE 10TH PERCENTILE FOR 850MB TEMPERATURES FOR
THIS TIME OF YEAR AND SIGNALS BELOW NORMAL SURFACE TEMPERATURES ARE
MORE LIKELY. WHAT DOES THAT MEAN AT THE SURFACE? TEMPERATURES WILL
FIRST COOL TO MORE SEASONAL VALUES ON THURSDAY WITH HIGHS IN THE 60S
TO LOW 70S. FRIDAY INTO THE WEEKEND, HIGH TEMPERATURES BECOME
SEASONABLY COOL IN THE 60S WITH MOST SPOTS RUNNING AROUND 2 TO 5
DEGREES BELOW NORMAL. OVERNIGHT LOW TEMPERATURES WILL ALSO
EXPERIENCE A COOLING TREND WITH LOWS GRADUALLY COOLING FROM THE 50S
TO MID TO LOW 40S. PORTIONS OF THE INTERIOR CENTRAL COAST MAY SEE
LOW TEMPERATURES DROPPING INTO THE UPPER 30S STARTING SUNDAY.
TEMPERATURES ARE ONLY PART OF OUR WEATHER CHANGE UP, HOWEVER, SO NOW
WE TURN TO THE MUCH ANTICIPATED PRECIPITATION FORECAST FOR THE
UPCOMING WEEK. AS OUR CUT-OFF LOW ARRIVES, IT WILL BRING A FAIRLY
PERSISTENT STREAM OF MOISTURE WITH IT. PWAT VALUES ARE AROUND 0.8-
0.9" WITH THE SLOW MOVEMENT OF THE LOW SOUTHWARDS ALONG THE
CALIFORNIA COAST KEEPING THE MOISTURE TRAINING OVER THE BAY
AREA/CENTRAL COAST. COASTAL DRIZZLE BECOMES MORE LIKELY WEDNESDAY
NIGHT INTO THURSDAY MORNING WITH SCATTERED SHOWERS MOVING IN
THROUGHOUT THE DAY ON THURSDAY. SHOWERS THEN CONTINUE THROUGH THE
WEEKEND THANKS TO THE SLOW MOVEMENT OF THE LOW. PRECIPITATION TOTALS
HAVE INCREASED SLIGHTLY WITH MOST OF THE LOWER ELEVATIONS SEEING
BETWEEN 0.25-0.35" OF PRECIPITATION. THE HIGHER ELEVATIONS REMAIN
THE BIG WINNERS WITH UP TO 0.75" OF RAIN EXPECTED. THE HIGHEST PEAKS
OF THE SANTA CRUZ MOUNTAINS AND THE SANTA LUCIA RANGE WILL SEE
ANYWHERE FROM AN INCH TO AN INCH AND A HALF OF RAIN. RAINFALL
REMAINS BENEFICIAL AND IS HELPING TO REDUCE NEAR TERM FIRE CONCERNS.
LOCALLY GUSTY WINDS ARE EXPECTED DIRECTLY ALONG THE COASTLINE AND
ACROSS THE HIGHER ELEVATIONS BUT CONDITIONS ARE NOT FORECAST TO MEET
WIND ADVISORY CRITERIA.
THUNDERSTORMS ARE STILL POSSIBLE THURSDAY AFTERNOON AND AGAIN FRIDAY
AFTERNOON. THE SETUP NOW LOOKS MORE FAVORABLE FOR THUNDERSTORMS ON
FRIDAY (20-25%) RATHER THAN ON THURSDAY (10-15%). MUCAPE VALUES
STILL LOOK GOOD BUT LOW LEVEL SHEAR REMAINS MINIMAL. IF ANY
THUNDERSTORMS DO DEVELOP THE MOST LIKELY HAZARDS WOULD BE LOCALLY
HEAVY RAIN, GUSTY WINDS, AND THE POTENTIAL FOR SMALL HAIL.
AVIATION
(18Z TAFS)
ISSUED AT 1129 AM PDT MON APR 6 2026
THE MARINE LAYER MADE A TRIUMPHANT RETURN LAST NIGHT AND WILL
REMAIN THE MOST IMPORTANT FEATURE FOR AVIATION WEATHER OVER THE
NEXT FEW DAYS. THE CURRENT MARINE LAYER DEPTH IS AROUND 1500 FEET,
DEEP ENOUGH TO ALLOW SOME IMPACTS TO MAKE IT ALL TERMINALS WITH
THE EXCEPTION OF LIVERMORE. THE STRATUS IS GRADUALLY MIXING OUT
THIS MORNING, WITH CLEAR SKIES EXPECTED FOR ALL TERMINALS AWAY
FROM THE IMMEDIATE COAST (SORRY HALF MOON BAY) THROUGH THE
AFTERNOON AND EARLY EVENING. THERE IS VERY HIGH CONFIDENCE THAT
THE MARINE LAYER STRATUS WILL RETURN OVERNIGHT.
VICINITY OF SFO...WHILE WE FEEL CONFIDENT THAT THE MARINE LAYER
STRATUS WILL RETURN OVERNIGHT, THE EXACT IMPACT AT SFO IS LESS
CERTAIN. AS WE SAW THIS MORNING, MICROSCALE EDDIES AND DOWNSLOPING
CAN CREATE SOME CLEAR PATCHES AT AND AROUND THE TERMINAL. IF A CLOUD
DECK DOES MOVE OVER SFO, EXPECT HIGH IFR OR LOW MVFR CEILING HEIGHTS.
SFO BRIDGE APPROACH...VFR WITH CLOUDS CONFINED NORTH OF THE TERMINAL.
MONTEREY BAY TERMINALS...THE MARINE LAYER IS A LITTLE MORE SHALLOW
AT THESE TERMINALS, WHICH BROUGHT LOWER CEILINGS AND AND EARLIER
CLEARING TIME THAN THE BAY AREA. WHILE THE AFTERNOON SHOULD BE
CLEAR, THE STRATUS BANK IS HANGING OUT JUST OFF THE COAST AND THERE
IS A CHANCE FOR ENCROACHMENT OVER MRY AT ANY TIME. A SIMILAR TREND
IS EXPECTED TONIGHT WITH IFR CEILINGS EXPECTED THROUGH MID TUESDAY
MORNING AT BOTH MRY AND SNS.
MARINE
(TODAY THROUGH SATURDAY)
ISSUED AT 1129 AM PDT MON APR 6 2026
HIGH PRESSURE OFF THE CALIFORNIA COAST WILL MAINTAIN LIGHT TO
MODERATE BREEZES ACROSS THE COASTAL WATERS THROUGH THE WEEK.
LOCALLY FRESH BREEZES WILL DEVELOP ALONG THE BIG SUR COAST THIS
AFTERNOON WITH THE STRONGEST WIND NEAR AND SOUTH OF POINT SUR.
UNSETTLED WEATHER RETURNS MID TO LATE WEEK, BRINGING LIGHT
SHOWERS, A SLIGHT CHANCE OF THUNDERSTORMS, AND MODERATE SEAS.
WINDS INCREASE NEXT WEEKEND WITH A FRESH BREEZE EXPECTED OVER THE
NORTHERN COASTAL WATERS.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 9 PM PDT TUESDAY FOR PT PINOS TO PT
PIEDRAS BLANCAS 0-10 NM.
SHORT TERM...KENNEDY
LONG TERM....KENNEDY
AVIATION...FLYNN
MARINE...FLYNN
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