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FXUS66 KMTR 291740
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
940 AM PST WED JAN 29 2025
..NEW AVIATION
SYNOPSIS
ISSUED AT 231 AM PST WED JAN 29 2025
HIGH PRESSURE WILL DOMINATE THE REGION LEADING TO CHILLY MORNINGS
AND MILD DAYS THROUGH THURSDAY. COASTAL FOG AND STRATUS THIS
MORNING AND LIKELY AGAIN TONIGHT AND INTO THURSDAY MORNING. A
PATTERN CHANGE HAPPENS FRIDAY, WITH WET WEATHER RETURNING FOR THE
WEEKEND. RAIN CHANCES ARE BEST FOR THE NORTH BAY AND DECREASE AS YOU
MOVE SOUTHWARDS.
UPDATE
ISSUED AT 821 AM PST WED JAN 29 2025
CLOUDY CONDITIONS PREVAIL OVER MUCH OF THE REGION THIS MORNING WITH
TEMPERATURES UNDER CLOUD COVER REMAINING INSULATED FROM THE COLD
TEMPERATURES. HOWEVER, A FEW SPOTS ACROSS THE REGION DID DIP INTO
THE MID 20S TO JUST BELOW FREEZING. THUS, WILL ALLOW THE
FROST/FREEZE PRODUCTS TO EXPIRE AT 9 AM. OTHERWISE, WILL BE
CHALLENGING FOR DAY TIME HIGH TEMPERATURES DEPENDING ON HOW QUICKLY
LOW CLOUDS DISSIPATE AND IF THEY DISSIPATE AT ALL. ALSO, FORECASTING
TEMPERATURES OVERNIGHT TONIGHT WILL BE A CHALLENGE AS CLOUDS ARE
EXPECTED TO RETURN TO INLAND VALLEYS. OTHERWISE, NO FORECAST UPDATES
ARE ANTICIPATED AT THIS TIME AS THE REMAINING FORECAST REMAINS ON
TRACK.
RGASS
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 231 AM PST WED JAN 29 2025
WATER VAPOR SATELLITE IMAGERY THIS MORNING SHOWS THE OMEGA BLOCK
OVER THE EASTERN PACIFIC, WITH HIGH PRESSURE SITTING OVER THE
REGION. LOOKING ACROSS OTHER CHANNELS, SUCH AS THE NIGHTTIME
MICROPHYSICS AND NIGHT FOG, WE CAN SEE STRATUS WORKING TROUGH THE
VALLEYS OF THE GREATER BAY AREA AND CENTRAL COAST. OBSERVATIONS SHOW
A FEW POCKETS OF FOG IN THE NORTH BAY, WHERE WINDS ARE EITHER CALM
OR LIGHT, WHILE OTHER AREAS REPORT LOW CLOUDS. STRATUS LOOKS TO HANG
AROUND THROUGH THE MORNING AND MAY STRUGGLE TO MIX OUT COMPLETELY
DURING THE AFTERNOON HOURS. THIS COULD HINDER TEMPERATURE GROWTH AND
KEEP TEMPERATURES COOLER THAN FORECAST. WITH THAT BEING SAID, HIGHS
TODAY ARE FORECAST TO BE IN THE LOW TO MID 50S AND GENERALLY IN THE
MID TO UPPER 50S FOR VALLEYS, PERHAPS LOW 60S. TEMPERATURES REMAIN
ON THE MIND FOR TONIGHT, WITH THE QUESTION BEING HOW LOW WILL THEY
GO? SHOULD THE MORE OPTIMISTIC FORECAST OCCUR FOR THE CLEARING OF
STRATUS, THE SALINAS VALLEY SHOULD CLEAR OUT AS WELL AS THE NORTH
BAY VALLEYS. UNFORTUNATELY, HI-RES GUIDANCE IS A BIT DIVIDED ON FAST
STRATUS RETURNS. CONFIDENCE IS LOWEST IN THE BAY AREA, WHERE AS THE
CENTRAL COAST SEEMS TO HAVE A LATER ONSET ESPECIALLY FOR THE
SOUTHERN SALINAS VALLEY. AT THIS TIME, OPTED TO NOT CHANGE THE MINT
FORECAST AND ALLOW THE THE FREEZE WATCH TO REMAIN IN PLACE FOR MUCH
OF THE REGION.
LONG TERM
(THURSDAY THROUGH TUESDAY)
ISSUED AT 231 AM PST WED JAN 29 2025
OMEGA BLOCKING LASTS THROUGH THURSDAY, BEFORE UPPER LEVEL RIDGING
BECOMES FLATTENED BUT AN UPPER LEVEL TROUGH MOVING INTO THE PACNW.
UPPER LEVEL FLOW OVER THE BAY AREA AND CENTRAL COAST SHOULD BE ZONAL
THROUGH THE WEEKEND. ENSEMBLE TABLES FOR THE GEFS, NAEFS, AND ENS
HAVE SHOWN AN INCREASE IN PWATS AND IVT OVER THE REGION FOR THE
WEEKEND. PWATS GENERALLY RANGE FROM 0.75-1.25" NOW, FAVORING MORE
MOISTURE OVERHEAD. GUIDANCE STILL FAVORS THE NORTH BAY FOR THE
WEEKEND, THOUGH THERE HAS BEEN A SLIGHT SHIFT SOUTHWARD GIVING THE
GREATER BAY AREA A BETTER SHOT WETTING RAIN. AS YOU MOVE SOUTH INTO
THE CENTRAL COAST CHANCES DECREASE. WE MAY CONTINUE TO SEE
FLUCTUATIONS IN TIMING AND AMOUNTS OVER THE NEXT FEW DAYS AS HI-RES
MODELS WILL START TO CAPTURE THIS EVENT.
NEXT WEEK, ZONAL FLOW MOVES SOUTH AS THE MID AND UPPER LEVEL LOW
DROPS SOUTHWARD. THIS WILL BRING MORE WIDESPREAD RAIN THE AREAS
SOUTH OF THE GOLDEN GATE AND ACROSS THE CENTRAL COAST. THERE REMAINS
A GREAT DEAL OF UNCERTAINTY BEYOND MONDAY, SO EXPECT THE FORECAST TO
CHANGE IN THE COMING DAYS AND AS WE GET CLOSER TO THE WEEKEND.
AVIATION
(18Z TAFS)
ISSUED AT 940 AM PST WED JAN 29 2025
CLOUD COVER AND FOG CONTINUES TO ERODE AROUND THE MORE INLAND AREAS
BUT SOME OF THE COASTAL SITES WILL SEE CIGS THROUGH THE TAF PERIOD.
LOWER CIGS MOVE INLAND IN THE EVENING AND BECOME WIDESPREAD INTO THE
LATE NIGHT. VISIBILITIES REDUCE AS MIST AND FOG FORM INTO THE LATE
NIGHT PARTICULARLY IN THE NORTH BAY. CLOUD COVER AND FOG BEGINS TO
ERODE LATE THURSDAY MORNING BUT CIGS COULD LINGER IN FAVORED SPOTS
INTO THE AFTERNOON. WINDS STAY LIGHT TO MODERATE THROUGH THE TAF
PERIOD.
VICINITY OF SFO...MVFR CIGS LINGER THROUGH THE FIRST HALF OF THE
AFTERNOON BEFORE SCATTERING AS MODERATE WEST WINDS BUILD. VFR LASTS
INTO THE EARLY NIGHT BEFORE MVFR CIGS FILL AROUND THE SF BAY. CIGS
ARE EXPECTED TO LAST THROUGH MUCH OF THURSDAY BEFORE SCATTERING.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...MVFR CIGS LINGER INTO THE AFTERNOON BEFORE
SCATTERING AS MODERATE WEST WINDS BUILD. AS WINDS REDUCE INTO THE
EVENING, MVFR CIGS BUILD ALONG THE COAST AND MOVE INLAND, FILLING
OVER THE TERMINALS. THESE CIGS ARE EXPECTED TO LAST BEYOND THE TAF
PERIOD.
MARINE
(TODAY THROUGH MONDAY)
ISSUED AT 821 AM PST WED JAN 29 2025
WINDS AND SEAS STAY LIGHT THROUGH FRIDAY. UNSETTLED WEATHER
RETURNS FRIDAY INTO NEXT WEEK AS AN UPPER LEVEL LOW BRINGS GUSTY
CONDITIONS TO THE NORTHERN WATERS AND WIDESPREAD RAIN OVER THE
WATERS.
MTR WATCHES/WARNINGS/ADVISORIES
CA...FREEZE WATCH FROM LATE TONIGHT THROUGH THURSDAY MORNING FOR
CAZ504-506-508-510-512>518-528>530.
PZ...NONE.
SHORT TERM...KR
LONG TERM....KR
AVIATION...MURDOCK
MARINE...MURDOCK
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