150
FXUS66 KMTR 151208
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
508 AM PDT TUE APR 15 2025
..NEW AVIATION
SYNOPSIS
ISSUED AT 349 AM PDT TUE APR 15 2025
COOLER TEMPERATURES ARE FORECAST THROUGH THURSDAY AND WARMER WEATHER
RETURNING FOR THE WEEKEND. SLIGHT CHANCE FOR THUNDERSTORMS ON
WEDNESDAY, PRIMARILY FOR THE CENTRAL COAST AND SOUTHERN COASTAL
RANGE.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 349 AM PDT TUE APR 15 2025
SATELLITE IMAGERY SHOWS THE UPPER LEVEL LOW SPINNING WEST OF OF
SOUTHERN CA THIS MORNING. WATER VAPOR IMAGERY SHOWS RATHER DRY AIR
ACROSS MUCH OF THE LOWER LEVELS WITH MOISTURE INCREASING AS YOU GO
UP IN THE ATMOSPHERE. CONVECTIVE INGREDIENTS FOR TODAY, AND IN
PARTICULAR THIS MORNING, LOOK TO BE SLIGHTLY HEALTHIER THAN
TOMORROW; HOWEVER, BASED ON SOUNDINGS ACROSS THE AREA WE'LL NEED TO
OVERCOME THE DRY AIR AND CIN TO REALLY GET ANYTHING GOING. SHOULD IT
HAPPEN, WE MIGHT BE ABLE TO GET A FEW SHOWERS OR THUNDERSTORMS OUT
OF IT WITH LIGHTNING AND PERHAPS A FEW BOUTS OF GUSTY WINDS. A NOTE
ABOUT THE DRIER AIR, THAT INCREASES THE DCAPE VALUES PUTTING US
CLOSE TO 800 J/KG SUPPORTING STRONGER DOWNDRAFTS SHOULD SHOWERS OR
STORMS FORM. CONFIDENCE IS LOW ON THIS HAPPENING, THUS I OPTED TO
KEEP POP AND THE MENTION OF THUNDER OUT OF THE FORECAST FOR TODAY.
LONG TERM
(WEDNESDAY THROUGH MONDAY)
ISSUED AT 349 AM PDT TUE APR 15 2025
THE FORECAST LOOKS TO BE ON TRACK FOR THE LONG TERM, WITH THE MAIN
FEATURE BEING THE POSSIBILITY FOR ELEVATED THUNDERSTORMS ON
WEDNESDAY. LOW PRESSURE IS EXPECTED TO MOVE ONSHORE INTO SOUTHERN CA
SENDING A SLUG OF MOISTURE TO THE NORTH. THIS SHOULD HELP KICK UP
SHOWERS AND PERHAPS THUNDERSTORM OR TWO OVER THE CENTRAL COAST AND
OUR PORTION OF THE SOUTHERN COASTAL RANGE. LOOKING AT HI-RES
GUIDANCE AND SOUNDINGS, CAPE HAS QUITE THE RANGE OF POSSIBILITIES.
THE NAM AND THE HRRR ARE THE MOST AGGRESSIVE WITH UP TO 500 J/KG OF
MUCAPE. BUT WHEN YOU LOOK AT THE SOUNDINGS, THERE IS A LOT OF CIN TO
OVERCOME. KEPT THE MENTION OF THUNDER IN THE FORECAST OVER CENTRAL
COAST AND UP INTO THE DIABLO RANGE, THOUGH CONFIDENCE REMAINS ON THE
LOWER END.
HEADING INTO THURSDAY, A SECONDARY SYSTEM SLIDES INTO NORTHERN CA
FROM THE NORTH WHILE THE UPPER LOW OVER SOUTHERN CA MEANDERS EAST.
DRY WEATHER IS EXPECTED, WHICH MAY BE ACCOMPANIED ACCOMPANIED WITH
SOME BREEZIER WINDS. AN UPPER LEVEL HIGH BUILDS OVER THE EASTERN
PACIFIC DURING THIS TIME, WHICH WILL EVENTUALLY NOSE IN FOR FRIDAY
AND SATURDAY. MORE ZONAL TO WEAK TROUGHING IS EXPECTED BY SUNDAY.
COOLER TEMPERATURES PREVAIL THROUGH THURSDAY, WITH A WARMING TREND
EXPECTED FOR THE WEEKEND.
AVIATION
(12Z TAFS)
ISSUED AT 447 AM PDT TUE APR 15 2025
MVFR/IFR ACROSS THE BOARD THIS MORNING AS MARINE LAYER MOISTURE
INCREASES AMID BROAD SOUTHERLY FLOW AS A WEAK UPPER LEVEL
DISTURBANCE APPROACHES THE REGION. FAIRLY CONFIDENCE ON CLEARING
TIMES TO VFR WITH THIS ISSUANCE, AND WILL LIKELY BE ANOTHER DAY OF
MOSTLY CLEAR SKIES FOR MOST TERMINALS AND STRATUS LINGERING ALONG
THE IMMEDIATE COAST. THE UNCERTAINTY LIES IN THE DEGREE OF
INFLUENCE FROM SOME MID-LEVEL CLOUDINESS THAT WILL BE INCREASING
THROUGH TODAY. THAT WILL ULTIMATELY BE RESPONSIBLE FOR ADDITIONAL
UNCERTAINTY IN CIGS TONIGHT. HOWEVER, THE MOIST MARINE LAYER WILL
BE EXPANDING THROUGH THE PERIOD, SO CIGS THAT DO DEVELOP WILL MORE
THAN LIKELY BE CLOSER TO THE MVFR SIDE OF THE IFR/MVFR SPLIT.
VICINITY OF SFO...MVFR CIGS THROUGH THIS MORNING, THEN VFR FROM
ABOUT THE 19Z HOUR THROUGH THIS EVENING. INCREASING MID-LEVEL
CLOUDINESS IN RESPONSE TO AN APPROACHING UPPER LEVEL DISTURBANCE,
BUT SHOULD RESULT IN MINIMAL IMPACTS TO OPERATIONS, IF ANY.
EXPECTED MVFR CIGS ONCE AGAIN BY EARLY WEDNESDAY MORNING, BUT
UNCERTAINTY IS A BIT HIGHER THEN DUE TO THE MID-LEVEL CLOUDS AND
DYNAMICS OF THE UPPER LOW.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...SOLID IFR/MVFR THIS MORNING, CLEARING TO
VFR BY MID-TO-LATE MORNING, BUT HOLDING ON TO SOME MID-LEVEL CLOUD
COVER THROUGH MUCH OF THE DAY. RETURN OF MARINE STRATUS THIS
EVENING IS A LITTLE MORE UNCERTAIN DUE TO THE INFLUENCE OF HIGHER
CLOUD DECKS AND THE EXACT APPROACH OF A WEAK UPPER LEVEL
DISTURBANCE. NONETHELESS, EXPECTING ANOTHER ROUND OF IFR/MVFR CIGS
INTO WEDNESDAY MORNING.
MARINE
(TODAY THROUGH SUNDAY)
ISSUED AT 349 AM PDT TUE APR 15 2025
LIGHT TO MODERATE WINDS LAST THROUGH MUCH OF THE WEEK. MODERATE
SEAS HOLD THROUGH MIDWEEK OR SO, AND THEN BUILD INTO THE LATTER
PORTION OF THE WORK WEEK. NORTHWESTERLY WINDS LOOK TO BECOME FRESH
FOR THE WEEKEND LEADING TO CONCERNS FOR SMALLER CRAFT.
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
SHORT TERM...KR
LONG TERM....KR
AVIATION...BEHRINGER
MARINE...KR
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