571
FXUS66 KMTR 051833
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1133 AM PDT SUN JUL 5 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 1200 AM PDT SUN JUL 5 2026
- COOLER TEMPERATURES TODAY AND MONDAY BEFORE A WARMING TREND
ARRIVES FOR THE SECOND HALF OF THE WEEK
- MARINE LAYER STRATUS DEVELOPS EACH EVENING AND OVERNIGHT BEFORE
RETREATING TO THE COAST EACH MORNING AND AFTERNOON
UPDATE
ISSUED AT 904 AM PDT SUN JUL 5 2026
THE THREAT FOR HIGH-BASED CONVECTION HAS GREATLY DIMINISHED AS THE
SHORT-WAVE TROUGH CONTINUES TO PUSH INLAND AWAY FROM THE BAY AREA
AND CENTRAL COAST. MID/HIGH LEVEL CLOUDS ALSO CONTINUE TO EXIT THE
REGION EARLIER THAN EXPECTED WITH LOW CLOUDS FORECAST TO CONTINUE TO
RETREAT TO THE COAST BY THIS AFTERNOON. HOWEVER, STILL EXPECTING
COOLER TEMPERATURES AS A RESULT OF THE MID/UPPER LEVEL TROUGH. NO
SIGNIFICANT CHANGES TO THE ONGOING FORECAST AT THIS TIME.
RGASS
SHORT TERM
ISSUED AT 1200 AM PDT SUN JUL 5 2026
(TODAY AND TONIGHT)
STRATUS IS EXPANDING ACROSS THE COASTAL REGIONS AND INTO THE
VALLEYS, BUT HIGH CLOUDS ASSOCIATED WITH ELEVATED MOISTURE ARE
MAKING IT NEARLY IMPOSSIBLE TO TRACK THE STRATUS. RADAR ECHOES ARE
COMING IN ABOVE SAN LUIS OBISPO COUNTY INTO SOUTHERN MONTEREY
COUNTY. HOWEVER, THERE HAVEN'T BEEN A LOT OF REPORTS OF RAIN AT THE
SURFACE , ALTHOUGH PASO ROBLES AIRPORT DID REPORT LIGHT RAIN
STARTING AROUND 1015 PM. THE 00Z (5 PM) SOUNDING FROM VANDENBERG
SFB, IN ADDITION TO AIRCRAFT-DERIVED SOUNDINGS AT OAK AND SFO,
REVEAL THE MAIN THING KEEPING THE SURFACE GENERALLY DRY IS A LAYER
OF VERY DRY AIR STARTING JUST ABOVE THE MARINE LAYER INVERSION AT
1500-2000 FEET UP TO AROUND 6000-7000 FEET ABOVE SEA LEVEL. WITHIN
THE LAYER, DEW POINTS AS LOW AS -10 DEGREES CELSIUS, OR 14 DEGREES
FAHRENHEIT, WERE OBSERVED, WHILE AIR TEMPERATURES IN THE MIDDLE TO
UPPER 60S WERE REPORTED, CORRESPONDING TO RELATIVE HUMIDITY VALUES
AROUND 12 TO 13%. BASED ON THE OBSERVED CONDITIONS, SOME SHOWERS
COMING ACROSS THE CENTRAL COAST AND BAY AREA CAN'T BE RULED OUT
THROUGH THE REST OF THE NIGHT THROUGH AROUND NOON, AND I HAVE OPTED
TO PUT A WIDE AREA OF SLIGHT SHOWER CHANCES (10-15% PROBABILITY)
THROUGH THE AFOREMENTIONED AREA, ALTHOUGH NOTE THAT SHOWERS ARE
EXPECTED TO BE ISOLATED TO WIDELY ISOLATED. AS FOR CONVECTIVE
CHANCES, THEY ARE EXPECTED TO BE VERY SMALL, NEARLY NEGLIGIBLE, AS
LIMITED INSTABILITY AND A LACK OF LIFTING MECHANISMS WILL TAMP DOWN
CHANCES FOR THUNDERSTORMS.
TODAY SHOULD SEE A COOLDOWN WITH A SHORTWAVE TROUGH COMING THROUGH
THE STATE. HIGH TEMPERATURES WILL RANGE FROM THE MIDDLE 70S TO THE
LOWER 80S IN THE INLAND VALLEYS, UP TO THE UPPER 80S TO LOWER 90S IN
THE WARMEST INTERIOR SPOTS, THE MIDDLE 60S TO THE MIDDLE 70S NEAR
THE BAYS, AND THE UPPER 50S TO LOWER 60S ALONG THE PACIFIC COAST.
STRATUS COVERAGE SHOULD RETREAT TO THE IMMEDIATE COAST THIS
AFTERNOON, ALONG WITH A CLEARING OF THE HIGHER CLOUDS AS THE PULSE
OF MOISTURE MOVES ON. BREEZY ONSHORE PATTERN WINDS SHOULD DEVELOP IN
THE AFTERNOON AND EVENING WITH GUSTS REACHING 20 TO 25 MPH THROUGH
LONG TERM
ISSUED AT 1200 AM PDT SUN JUL 5 2026
(MONDAY THROUGH SATURDAY)
THE LONG TERM OUTLOOK CONTINUES TO SHOW A BALANCE BETWEEN RIDGING
ACROSS THE WESTERN UNITED STATES AND A SERIES OF TROUGHS IN THE
EASTERN PACIFIC THROUGH THE NEXT FEW DAYS. MONDAY WILL NOT HAVE A
CHANCE FOR SHOWERS, BUT OTHERWISE CONDITIONS SHOULD BE SIMILAR TO
TODAY. TOWARDS THE MIDDLE AND LATER PARTS OF THE WEEK, TEMPERATURES
WILL GRADUALLY RISE INLAND AS THE RIDGE STRENGTHENS AND MOVES INTO
THE DESERT SOUTHWEST, WITH A PARTICULAR EMPHASIS ON WEDNESDAY
THROUGH FRIDAY WHEN LOCAL TEMPERATURE GRADIENTS RANGE FROM THE LOWER
TO MIDDLE 60S AT THE IMMEDIATE COAST TO THE UPPER 80S TO LOWER 90S
IN THE INLAND VALLEYS, TO THE TRIPLE DIGITS UP TO 105 WITHIN THE
WARMEST SPOTS OF SOUTHERN MONTEREY COUNTY. BEYOND THE 7-DAY OUTLOOK,
ENSEMBLE MODEL CLUSTER ANALYSIS IS GENERALLY IN LINE WITH THE RIDGE
AXIS PARING BACK TO THE INTERMOUNTAIN WEST FOR THE UPCOMING WEEKEND
(JULY 11 TO 12), WHICH WOULD SUPPORT A RETURN TO CONDITIONS SIMILAR
TO THOSE EXPECTED FOR THE NEXT COUPLE OF DAYS, WHILE CPC OUTLOOKS
LEAN TOWARDS TEMPERATURES REMAINING ABOVE THE SEASONAL AVERAGE
THROUGH THE MONTH OF JULY.
AVIATION
(18Z TAFS)
ISSUED AT 1131 AM PDT SUN JUL 5 2026
LINGERING MVFR STRATUS IS CURRENTLY SCATTERING OUT OF THE REMAINING
TERMINALS. VFR CONDITIONS PREVAIL THROUGH THE DAY WITH GENTLE TO
MODERATE WINDS (AROUND 12-16KT) ACROSS OUR REGION. NORTH BAY
TERMINALS WILL EXPERIENCE SOUTH TO SOUTHWEST WINDS. TERMINALS SOUTH
OF THE GOLDEN GATE WILL EXPERIENCE WEST TO NORTHWEST WINDS. LOW
CONFIDENCE FOR CLEARING AT KHAF FOR A PROLONGED PERIOD OF TIME. ANY
SCATTERING THAT DEVELOPS AT KHAF MAY BE SHORT-LIVED WITH MVFR
CONDITIONS PREVAILING THROUGH THE MAJORITY OF THE DAY. THE MARINE
LAYER RETURNS THIS EVENING WITH A PATTERN SIMILAR TO THE PREVIOUS
NIGHT. ANTICIPATE BORDERLINE MVFR-IFR CEILINGS AFTER 02-03Z MONDAY.
CEILINGS IN THE INTERIOR EAST AND SOUTH BAY VALLEYS DEVELOP AFTER
09Z MONDAY. HIGH CONFIDENCE THAT KSTS WILL DROP DOWN TO LIFR
CONDITIONS. LIFR CEILINGS ARE ALSO PROBABLE FOR KHAF, THOUGH
CONFIDENCE IS TOO LOW TO INCLUDE IN THE TAF. CONDITIONS IMPROVE TO
VFR BEGINNING 17Z MONDAY.
VICINITY OF SFO...MODERATE NORTHWEST BREEZES AROUND 16 KT PREVAIL
THROUGH THE AFTERNOON AND DIMINISH TO A GENTLE WESTERLY BREEZE
(~8KT) OVERNIGHT. MEDIUM CONFIDENCE ON TIMING OF STRATUS TONIGHT AS
IT MAY DEVELOP AN HOUR OR TWO LATER.
SFO BRIDGE APPROACH...SIMILAR TO SFO. MVFR CEILINGS MAY DEVELOP A
FEW HOURS AFTER SFO AROUND 10-11Z MONDAY AND PERSIST THROUGH 16-17Z.
MONTEREY BAY TERMINALS...VFR WITH NORTHWEST WINDS AROUND 10-12KT
DEVELOPING THIS AFTERNOON UNTIL THE STRATUS DECK ROLLS IN AT 02Z
MONDAY. HIGH CONFIDENCE THAT IFR CEILINGS ARE EXPECTED TO IMPACT
BOTH SNS AND MRY AGAIN THIS EVENING AND PERSIST THROUGH 17Z MONDAY.
NORTHWEST WINDS REMAIN GENTLE (~5 KT) OVERNIGHT.
MARINE
(TODAY THROUGH FRIDAY)
ISSUED AT 904 AM PDT SUN JUL 5 2026
A WEAK COLD FRONT TO THE NORTH WILL LEAD TO DECREASING NORTHERLY
FLOW OVER THE COASTAL WATERS THROUGH MONDAY. WINDS ARE FORECAST
TO INCREASE BY MONDAY NIGHT WITH FRESH TO STRONG BREEZES EXPECTED
TUESDAY AND THROUGH MUCH OF THE WEEK. SOME GUSTS NEAR GALE OR GALE
FORCE ARE POSSIBLE BY THURSDAY.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
SHORT TERM...DIALH
LONG TERM....DIALH
AVIATION...NAVARRETE
MARINE...RGASS
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