390
FXUS66 KMTR 051955
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1255 PM PDT SUN APR 5 2026
..NEW SHORT TERM, LONG TERM
KEY MESSAGES
UPDATED AT 1253 PM PDT SUN APR 5 2026
- ABOVE NORMAL TEMPERATURES CONTINUE TODAY; COOLING TREND BEGINS
TOMORROW
- BENEFICIAL RAIN AND A LOW POTENTIAL FOR THUNDERSTORMS MID TO
LATE WEEK
SHORT TERM
ISSUED AT 1253 PM PDT SUN APR 5 2026
(THIS EVENING THROUGH MONDAY)
ANOTHER WARM DAY IS ON THE BOOKS FOR TODAY. TEMPERATURES ARE RUNNING
AROUND 15 TO 20 DEGREES ABOVE NORMAL ACROSS THE INTERIOR AND AROUND
10 TO 15 DEGREES ABOVE NORMAL ALONG THE COAST. HIGHS TODAY WILL
LARGELY BE IN THE 80S ACROSS THE INTERIOR AND 70S ALONG THE
COASTLINE. THE PATTERN SHIFTS QUITE NOTABLY HEADING INTO MONDAY AS
UPPER LEVEL RIDGING EXITS EASTWARD AND WEAK SHORTWAVE UPPER LEVEL
TROUGHING MOVES IN. THIS WILL ALLOW THE MARINE LAYER TO DEVELOP
(ALBEIT A SHALLOW ONE BETWEEN 1000-1500 FT) AND WE WILL SEE A
"SOUTHERLY SURGE" OF STRATUS ALONG THE COAST. IF YOU LIVE ALONG THE
COAST, TOMORROW MORNING WILL FEEL VERY DIFFERENT THAN TODAY DUE TO
THE MUCH COOLER TEMPERATURES AND LOW LEVEL STRATUS. THERE MAY EVEN
BE SOME POTENTIAL FOR COASTAL DRIZZLE EARLY MONDAY MORNING. OFFSHORE
WINDS ARE EXPECTED TO BECOME ONSHORE AGAIN THIS AFTERNOON/EVENING
WITH ONSHORE WINDS TO THEN PREVAIL THROUGH THE REMAINDER OF THE
FORECAST. TEMPERATURES COOL MUCH MORE NOTICEABLY ON MONDAY WITH
INTERIOR HIGHS DROPPING INTO THE LOW TO MID 70S AND COASTAL HIGHS
INTO THE UPPER 50S TO LOW 60S. INTERIOR TEMPERATURES WILL STILL BE
RUNNING A FEW DEGREES ABOVE NORMAL WHILE COASTAL TEMPERATURES ARE
FAIRLY SEASONAL.
LONG TERM
ISSUED AT 1253 PM PDT SUN APR 5 2026
(MONDAY NIGHT THROUGH NEXT SATURDAY)
COOLER, WETTER WEATHER REMAINS ON TRACK TO ARRIVE MID TO LATE WEEK
AS OUR NEXT SYSTEM ARRIVES. UPPER LEVEL RIDGING TRIES TO REBUILD ON
TUESDAY, BUT, REMAINS COMPRESSED DUE TO A DEEP UPPER LEVEL LOW
MOVING INTO THE PNW. THIS RESULTS IN TUESDAY'S FORECAST STAYING
RATHER SIMILAR TO MONDAY'S WITH INTERIOR HIGHS IN THE 70S AND
COASTAL HIGHS IN THE 50S TO 60S. BY WEDNESDAY, WE START TO SEE OUR
NEXT RAINMAKER ON THE HORIZON. THE UPPER LEVEL TROUGH OVER THE PNW
WILL EXIT EASTWARDS INTO THE CENTRAL UNITED STATES WITH A SECOND LOW
PRESSURE SYSTEM APPROACHING CALIFORNIA FROM THE WEST. THIS SYSTEM
HAS SOME CHARACTERISTICS OF A CUT-OFF LOW WITH CLUSTER GUIDANCE
STARTING TO COME INTO BETTER AGREEMENT ABOUT IT. THE UPPER LEVEL LOW
LOOKS TO MOVE SOUTHWARDS PARALLEL TO CALIFORNIA'S COASTLINE BEFORE
MOVING INLAND OVER BAJA CALIFORNIA. THIS UPPER LEVEL LOW ORIGINATES
FROM THE GULF OF ALASKA AND IS BRINGING DOWN A MUCH COOLER AIRMASS.
AS THE COOLER AIRMASS ARRIVES, IT WILL BRING A RETURN OF MORE
SEASONAL TEMPERATURES IN THE 60S TO 70S ACROSS THE ENTIRE REGION.
ORIGINALLY RAIN LOOKED LIKELY TO RETURN ON WEDNESDAY BUT GUIDANCE
HAS SHIFTED WITH THE BULK OF THE RAIN NOW RETURNING THURSDAY AND
FRIDAY. CURRENT GUIDANCE SUGGESTS RAIN SHOWERS WILL BE FAIRLY
WIDESPREAD ACROSS OUR CWA BUT THEY WILL BE MORE SHOWERY THAN
STRATIFORM (UNIFORM OVER A LARGE AREA) IN NATURE. ENSEMBLE GUIDANCE
HAS TRENDED UPWARDS RECENTLY IN TERMS OF HOW MUCH PRECIPITATION WE
ARE EXPECTED. OVERALL THE RAIN IS STILL CLASSIFIED AS LIGHT AND
BENEFICIAL BUT WE CAN EXPECTED BETWEEN 0.5-0.75" ACROSS THE COASTAL
MOUNTAINS AND SANTA CLARA HILLS WHILE THE LOWER ELEVATIONS SEE
AROUND 0.25-0.35". THE HIGHEST AMOUNTS LOOK TO BE FARTHER SOUTH OVER
THE CENTRAL COAST IN THE SANTA CRUZ MOUNTAINS AND THE SANTA LUCIA
RANGE. LOCALLY BREEZY ONSHORE WINDS ARE EXPECTED ACROSS THE HIGHER
ELEVATIONS AND MOUNTAIN GAPS/PASSES BUT THESE ARE EXPECTED TO STAY
WELL BELOW WIND ADVISORY CRITERIA.
AS MENTIONED YESTERDAY, THERE IS A NON-ZERO CHANCE OF THUNDERSTORMS
ACROSS MUCH OF THE AREA THURSDAY AND FRIDAY. THE PROBABILITY OF
THUNDERSTORMS HAS INCREASED ACROSS THE REGION WITH A 15-20% CHANCE
OF THUNDERSTORMS ON THURSDAY AND FRIDAY. IN TERMS OF SUPPORT, LOW
LEVEL LAPSE RATES ARE DECENT (7-8 C/KM) WITH SEVERAL HUNDRED JOULES
OF LOW LEVEL MUCAPE BUT LOW LEVEL SHEAR IS FAIRLY NEGLIGIBLE. OUR
THUNDERSTORM CHANCES AND RAIN TOTALS WILL LARGELY DEPEND ON WHERE
THE SURFACE LOW PRESSURE SYSTEM MOVES INLAND AND HOW PROGRESSIVE THE
UPPER LEVEL SYSTEM IS. IF THE SURFACE LOW MAINTAINS ITS CURRENT PATH
AND MOVES INTO THE BAY AREA, THUNDERSTORMS WILL BE MORE LIKELY SOUTH
OF THE NORTH BAY AND ACROSS THE CENTRAL COAST. COMPARATIVELY, IF IT
SHIFTS MORE SOUTHERLY (I.E. MOVING IN OVER SLO), OUR THUNDERSTORM
CHANCES WOULD LARGELY GO AWAY. GIVEN THE INCREASE IN FORECAST
PRECIPITATION TOTALS, DRY LIGHTNING CONCERNS WITH THIS SYSTEM HAVE
LARGELY ABATED. THE MAJORITY OF LOCATIONS ARE NOW EXPECTED TO SEE
WETTING RAINS (PRECIPITATION TOTALS GREATER THAN OR EQUAL TO 0.1")
WHICH ALLEVIATES THE RISK OF FIRES STARTED BY LIGHTNING. ALL IN ALL,
THERE IS SOME POTENTIAL FOR THUNDERSTORMS WITH THIS UPCOMING SYSTEM
BUT CONFIDENCE IS NOT QUITE THERE YET. MAKE SURE TO STAY UP TO DATE
AS WE CONTINUE TO NARROW IN PRECIPITATION TOTALS AND THE POTENTIAL
FOR THUNDERSTORMS.
AVIATION
(18Z TAFS)
ISSUED AT 1042 AM PDT SUN APR 5 2026
VFR CONDITIONS CONTINUE THROUGH THE DAY BEFORE A SIGNIFICANT
PATTERN CHANGE BRINGS A MARINE LAYER FILLED WITH STRATUS AND
POSSIBLE FOG BACK TO THE COASTAL TERMINALS MONDAY MORNING.
VICINITY OF SFO...VFR CONDITIONS PREVAIL UNDER HIGH CLOUDS. WINDS
WILL SHIFT TO ONSHORE BY EARLY AFTERNOON AND REMAIN THEIR THROUGH
THE REMAINDER OF THE TAF PERIOD. A MARINE LAYER IS VERY LIKELY TO
REFORM OVERNIGHT, WITH MVFR-IFR IMPACTS LIKELY MONDAY MORNING.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR CONDITIONS TODAY, BUT THESE SOUTHERN
TERMINALS HAVE THE BEST CHANCE FOR MARINE LAYER IMPACTS EARLY
MONDAY MORNING. THE CEILING HEIGHT REMAINS A LITTLE UNCERTAIN,
BUT MVFR OR WORSE IMPACTS ARE LIKELY AT BOTH MRY AND SNS AND THERE
IS A SLIGHT CHANCE FOR FOG.
MARINE
(TODAY THROUGH FRIDAY)
ISSUED AT 1042 AM PDT SUN APR 5 2026
HIGH PRESSURE TO THE NORTH WILL MAINTAIN LIGHT TO MODERATE BREEZES
OVER THE COASTAL WATERS THROUGH EARLY NEXT WEEK. LOCALLY STRONGER
WINDS WILL DEVELOP NEAR THE BIG SUR COAST EARLY TO MIDWEEK.
UNSETTLED WEATHER RETURNS THE MIDDLE OF NEXT THANKS TO A LOW
PRESSURE SYSTEM OVER THE PACIFIC. THE LOW PRESSURE WILL BRING
FRESH GUSTS ACROSS THE NORTHERN WATERS AND MODERATE SEAS NEXT
WEEKEND. LIGHT SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS
PREVAILS OVER THE COASTAL WATERS MID TO LATE WEEK.
CLIMATE
ISSUED AT 110 PM PDT FRI APR 3 2026
THE FOLLOWING ARE THE RECORD HIGH TEMPERATURES AT THE LONG TERM
STATIONS FOR APRIL 5TH.
LOCATION APRIL 5TH
SANTA ROSA 90 IN 1939
KENTFIELD 88 IN 1924
SAN RAFAEL 87 IN 1957
NAPA 86 IN 1989, 1957
RICHMOND 83 IN 1989
LIVERMORE 84 IN 1989, 1916
SAN FRANCISCO 88 IN 1989
SFO AIRPORT 84 IN 1989
REDWOOD CITY 87 IN 1989
HALF MOON BAY 74 IN 2016
OAKLAND MUSEUM 85 IN 1989
SAN JOSE 89 IN 1989
SALINAS AIRPORT 95 IN 1989
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 3 PM MONDAY TO 3 AM PDT TUESDAY FOR PT
PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SHORT TERM...KENNEDY
LONG TERM....KENNEDY
AVIATION...FLYNN
MARINE...KENNEDY
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