874
FXUS66 KMTR 060453
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
953 PM PDT SUN APR 5 2026
..NEW AVIATION, MARINE
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
(06Z TAFS)
ISSUED AT 953 PM PDT SUN APR 5 2026
MVFR-IFR STRATUS IS DEVELOPING ALONG THE PACIFIC COAST, SPREADING
INLAND THROUGH THE EARLY MORNING HOURS ON MONDAY. HIGH CONFIDENCE IN
STRATUS IMPACTS AT THE IMMEDIATE COAST AND THE NORTHERN SF BAY
TERMINALS, MODERATE CONFIDENCE IN STRATUS IMPACTS AT SJC AND THE
INTERIOR TERMINALS. STRATUS WILL RETREAT TO THE IMMEDIATE COAST
THROUGH MONDAY MORNING, WITH ONSHORE FLOW RESUMING IN THE AFTERNOON.
STRATUS WILL RETURN TO THE COASTAL REGIONS MONDAY EVENING, WITH MORE
INLAND EXPANSION AFTER THE END OF THE 24-HOUR TAF PERIOD.
VICINITY OF SFO... MVFR-IFR STRATUS WILL BEGIN TO FLOW THROUGH THE
GOLDEN GATE IN THE NEXT SEVERAL HOURS, WITH MODERATE CONFIDENCE IN
THE EXACT TIMING OF THE STRATUS IMPACTS, WITH THE HIGH RESOLUTION
MODELS SUGGESTING THAT THE TERMINAL WILL BE SOCKED IN BY 10-12Z.
STRATUS WILL DISSIPATE MONDAY MORNING AROUND 18-20Z, WITH BREEZY
WEST-NORTHWEST WINDS IN THE AFTERNOON. SOME STRATUS WILL FLOW
THROUGH THE GOLDEN GATE MONDAY EVENING, BUT THE HIGHEST CONFIDENCE
FOR IMPACTS AT SFO COMES AFTER MIDNIGHT INTO EARLY TUESDAY MORNING.
SFO BRIDGE APPROACH... SIMILAR TO SFO.
MONTEREY BAY TERMINALS... LIGHT WINDS CONTINUE THROUGH THE NIGHT.
IFR CEILINGS DEVELOP IN THE NEXT COUPLE OF HOURS, WITH THE STRATUS
CLEARING THROUGH MONDAY MORNING BEFORE BREEZY NORTHWEST WINDS
DEVELOP IN THE AFTERNOON. HIGH RESOLUTION MODELS ARE DEPICTING
STRATUS RETURNING ON MONDAY EVENING AROUND 02-03Z.
MARINE
(TONIGHT THROUGH NEXT SATURDAY)
ISSUED AT 953 PM PDT SUN APR 5 2026
LIGHT TO MODERATE WINDS PERSIST OVER THE COASTAL WATERS FOR MUCH
OF NEXT WEEK. LOCALLY FRESH WINDS WILL BRIEFLY DEVELOP EARLY TO
MIDWEEK ACROSS THE COASTAL WATERS WITH LOCALLY STRONGER WINDS
POSSIBLE ALONG THE BIG SUR COAST. 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 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...DIALH
MARINE...DIALH
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