425
FXUS66 KMTR 312100
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
200 PM PDT SAT MAY 31 2025
..NEW SHORT TERM, LONG TERM
SYNOPSIS
ISSUED AT 825 AM PDT SAT MAY 31 2025
HIGH PRESSURE REMAINS IN PLACE, WITH HAZARDOUS HEAT EXPECTED ACROSS
OUR INLAND AREAS ONCE AGAIN TODAY. GIVEN THE DRY CONDITIONS, EXPECT
ELEVATED FIRE WEATHER CONDITIONS TO CONTINUE AS WELL. HOWEVER,
AN UPPER LEVEL TROUGH WILL BRING COOLER CONDITIONS TO THE REGION,
WITH MORE SEASONAL TEMPERATURES EXPECTED BY THIS COMING WEEK.
SHORT TERM
(THIS EVENING THROUGH SUNDAY)
ISSUED AT 200 PM PDT SAT MAY 31 2025
-MODERATE HEATRISK FOR FAR INTERIOR LOCATIONS AND THE SANTA CLARA
VALLEY, WHICH IS WHERE A HEAT ADVISORY WILL GO INTO EFFECT LATER
TODAY.
-ELEVATED FIRE WEATHER CONCERNS TODAY.
-NON-ZERO CHANCE FOR HIGH-BASED CONVECTION SATURDAY
WATER VAPOR IMAGERY CONTINUES TO SHOW NORTHERN CALIFORNIA
SANDWICHED BETWEEN A TROUGH OF LOW PRESSURE THAT IS PUSHING INTO
THE PACIFIC NORTHWEST THIS AFTERNOON AND AN UPPER LEVEL LOW OFF
THE NORTHERN BAJA PENINSULA, WITH THE HIGH PRESSURE OVER OUR
REGION STARTING TO GET SQUASHED. THAT SAID, WARM TO HOT
CONDITIONS ARE PREVAILING ACROSS THE BAY AREA AND THE CENTRAL
COAST, WITH MOST LOCATIONS RUNNING 2 TO 7 DEGREES WARMER THAN
THOSE AT THIS TIME YESTERDAY. THEREFORE, EXPECT OUR HIGH
TEMPERATURES TO BE SIMILAR THOSE OF YESTERDAY, WITH THE HEAT
ADVISORY REMAINING IN PLACE THROUGH 8 PM THIS EVENING FOR THROUGH
INTERIOR AREAS.
ONE OTHER THING THAT WE ARE CONTINUING TO WATCH FOR LATE THIS
AFTERNOON AND THIS EVENING IS THE NON-ZERO THREAT OF SOME
CONVECTION OVER SOUTHERN MONTEREY COUNTY. AT THIS TIME THOUGH,
CONFIDENCE IS RELATIVELY HIGH THAT IT WILL NOT OCCUR, AS THE BEST
AREAS OF INSTABILITY AND MOISTURE ARE TO OUR SOUTH AND EAST.
THAT SAID, SHOWERS AND ISOLATED THUNDERSTORMS HAVE START TO FIRE
ALONG THE SOUTHERN SIERRA, AS FAR NORTH AS YOSEMITE AND HETCH
HETCHY AND SOME MIDLEVEL MOISTURE IS STARTING TO SPREAD ACROSS
THE SOUTHERN PORTION OF THE CENTRAL SAN JOAQUIN VALLEY. THEREFORE,
CANNOT FULLY RULE OUT SOMETHING TRYING TO DEVELOP. JUST THINK IT
IS HIGHLY UNLIKELY, WITH THE THREAT BEING MINIMAL AT BEST.
AS FOR THE UPPER LEVEL TROUGH MOVING INTO THE PACIFIC NORTHWEST,
EXPECT IT TO DEEPEN ALONG THE WEST COAST OVER THE NEXT 24 HOURS,
WITH A BIT OF ENERGY EXPECTED TO CUT OFF FROM THE MAIN FLOW ON
SUNDAY OVER NORTHWEST CALIFORNIA COAST. AS A RESULT, EXPECT THE
MARINE LAYER TO REFORM AND DEEPEN TONIGHT TO AROUND 2000 FEET DEEP
IN RESPONSE TO THIS TROUGH, WITH A MORE PROMINENT STRATUS DECK
EXPECTED BY SUNDAY MORNING. 850 MB TEMPERATURES WILL ALSO FALL
BETWEEN 7 OR 8 DEGREES C BY TOMORROW, SO EXPECT COOLER CONDITIONS
TO DEVELOP REGION WIDE FOR SUNDAY. PALMER
LONG TERM
(SUNDAY NIGHT THROUGH NEXT FRIDAY)
ISSUED AT 200 PM PDT SAT MAY 31 2025
THE ENERGY THAT CUTS OFF FROM THE MAIN FLOW WILL FORM AN UPPER
LEVEL LOW OVER THE NORTHWEST COAST LATE IN THE DAY ON SUNDAY,
WHICH WILL SLOWLY DRIFT SOUTH ALONG THE COAST THROUGH TUESDAY
NIGHT. GIVEN THIS TROUGHY PATTERN, EXPECT TEMPERATURES TO CONTINUE
THEIR DOWNWARD TREND INTO MONDAY AND TUESDAY, AND THEN REMAIN
NEAR OR BELOW NORMAL THROUGH AT LEAST WEDNESDAY AND POTENTIALLY
INTO THURSDAY.
THIS UPPER LEVEL LOW WILL BE AN INTERESTING ONE. GIVEN THE TIME OF
YEAR AND THE FORECASTED TRACK, WOULD NOT EXPECT TO SEE MUCH IF ANY
RAIN WITH IT, OTHER THAN SOME MARINE LAYER DRIZZLE, ESPECIALLY
SUNDAY NIGHT AND MONDAY. HOWEVER, AS THIS LOW DROPS SOUTH IT
STARTS TO INTERACT WITH THE CURRENT UPPER LEVEL LOW TO OUR SOUTH
THAT IS KICKING INLAND. AS SUCH, THE ENSEMBLES ARE HINTING AT SOME
MIDLEVEL MOISTURE WRAPPING BACK MONDAY NIGHT AND INTO TUESDAY FOR
MONTEREY AND SAN BENITO. AT THIS POINT IN TIME, CONFIDENCE IS LOW
AS TO WHETHER OR NOT THIS WILL HAPPEN, SO HAVE LEFT OUT THE
MENTION OF SHOWERS FOR THESE AREAS. HOWEVER, THIS IS SOMETHING
THAT WE WILL NEED TO WATCH.
HIGH PRESSURE STARTS TO REBUILD FOR FRIDAY AND SATURDAY, SO EXPECT
DRY AND WARMER CONDITIONS DEVELOPING ONCE AGAIN. PALMER
AVIATION
(18Z TAFS)
ISSUED AT 1016 AM PDT SAT MAY 31 2025
VFR WILL PERSIST FOR ALL TERMINALS THROUGH THE AFTERNOON AND
EVENING. INLAND SITES SHOULD REMAIN VFR THROUGH THE FORECAST
PERIOD WITH A SLIGHT CHANCE OF MVFR/IFR CEILINGS EARLY SUNDAY
MORNING.
VICINITY OF SFO...VFR CONDITIONS WILL PERSIST THROUGH THE
REMAINDER OF THE DAY AND INTO THE OVERNIGHT HOURS, WITH MVFR/IFR
CEILINGS POSSIBLE A HOUR OR TWO BEFORE SUNRISE SUNDAY MORNING WITH
A COMPRESSED MARINE LAYER HUGGING THE COAST. PATCHY DENSE
FOG/DRIZZLE WILL ALSO BE POSSIBLE IN VICINITY OF THE BAY AREA
TERMINALS OVERNIGHT INTO SUNDAY MORNING. GUSTY ONSHORE WINDS WILL
PICK UP THIS AFTERNOON AND BEGIN TO EASE AFTER SUNSET.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR CONDITIONS WILL PERSIST THROUGH THE
REMAINDER OF THE DAY AND EARLY EVENING IFR/LIFR CIGS LIKELY LATER
THIS EVENING AFTER SUNSET. EXPECT TO CLEARING SUNDAY MORNING TO BE
SIMILAR TO TODAY, AROUND THE 15Z-16Z TIME PERIOD. DENSE
FOG AND DRIZZLE ARE ALSO POSSIBLE WITH THE COMPRESSED MARINE LAYER
HUGGING THE COASTLINE.
MARINE
(TODAY THROUGH THURSDAY)
ISSUED AT 355 AM PDT SAT MAY 31 2025
BREEZY TO GUSTY CONDITIONS CONTINUE OVER THE NORTHERN COASTAL
WATERS RESULTING IN STEEP WIND WAVES AND HAZARDOUS CONDITIONS FOR
SMALL CRAFTS. WINDS STRENGTHEN STARTING LATE SATURDAY INTO SUNDAY
WITH GALE FORCE GUSTS EXPECTED OVER THE NORTHERN COASTAL WATERS
AND STRONG GUSTS ACROSS THE SOUTHERN OUTER WATERS. ROUGH SEAS ARE
EXPECTED ACROSS THE OUTER WATERS LATE SATURDAY WITH SIGNIFICANT
WAVE HEIGHTS 10 TO 15 FEET ACROSS THE SOUTHERN OUTER WATERS AND UP
TO 22 FEET ACROSS THE NORTHERN OUTER WATERS. WINDS GRADUALLY EASE
BY TUESDAY BUT SIGNIFICANT WAVE HEIGHTS WILL REMAIN ELEVATED
THROUGH MID TO LATE WEEK.
FIRE WEATHER
ISSUED AT 355 AM PDT SAT MAY 31 2025
ELEVATED FIRE WEATHER CONCERNS WILL PERSIST TODAY. THE MARINE
LAYER IS COMPRESSED TO NEAR SEA LEVEL, WITH HIGHER ELEVATIONS
REMAINING DRY WITH MODERATE TO LOCALLY POOR HUMIDITY RECOVERY
TONIGHT. DAYTIME REMAIN ELEVATED FOR FAR INTERIOR LOCATIONS,
WHILE OTHER AREAS MODERATE SOME. COOLER WEATHER ARRIVES SUNDAY.
PEOPLE SHOULD BE MINDFUL TO AVOID ACTIVITIES THAT COULD SPARK A
GRASS FIRE.
CLIMATE
ISSUED AT 1128 PM PDT TUE MAY 27 2025
RECORD HIGH TEMPERATURES AT THE LONG TERM CLIMATE STATIONS
SATURDAY, MAY 31ST.
STATION MAY 31ST
SANTA ROSA 99F 1970
KENTFIELD 102F 2001
NAPA 103F 2001
RICHMOND 95F 2001
LIVERMORE 104F 2001, 1910
SAN FRANCISCO 90F 2001
SFO AIRPORT 91F 2001
REDWOOD CITY 99F 2001
HALF MOON BAY 77F 1997
OAKLAND DOWNTOWN 89F 2001
SAN JOSE 98F 1970
SALINAS AIRPORT 90F 1997
KING CITY 100F 2001
MTR WATCHES/WARNINGS/ADVISORIES
CA...HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR CAZ504-510-513-
516>518.
PZ...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 3 AM PDT SUNDAY
FOR SF BAY N OF BAY BRIDGE.
SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR PT ARENA
TO PT REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM.
GALE WARNING UNTIL 3 AM PDT SUNDAY FOR PT ARENA TO PT REYES 0-10
NM.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT SUNDAY FOR PT REYES TO
PIGEON PT 0-10 NM.
GALE WARNING UNTIL 3 PM PDT SUNDAY FOR PT ARENA TO PT REYES 10-
60 NM.
SMALL CRAFT ADVISORY UNTIL 3 PM PDT SUNDAY FOR PIGEON PT TO PT
PINOS 10-60 NM.
SHORT TERM...PALMER
LONG TERM....PALMER
AVIATION...JM
MARINE...JM
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