264
FXUS66 KEKA 072028
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
128 PM PDT TUE OCT 7 2025
SYNOPSIS
OFFSHORE FLOW WILL TURN MORE ONSHORE WEDNESDAY, HELPING
COOL CONDITIONS ACROSS THE AREA BUT ESPECIALLY ALONG THE COAST.
LIGHT RAIN WILL BUILD IN FRIDAY WITH SHOWERS CONTINUING THROUGH THE
WEEKEND.
DISCUSSION
GENERAL OFFSHORE FLOW, DRIVEN BY LOW
PRESSURE OFF OF THE CENTRAL CALIFORNIA COAST HAS CONTINUED TO PUSH
MARINE AIR AWAY, ALLOWING FOR UNUSUALLY HIGH COASTAL TEMPERATURES
ONCE AGAIN IN THE MID 70S. THOUGH NOT HIGH IN ABSOLUTE TERMS, SUCH
TEMPERATURES ARE SOME OF THE WARMEST OF THE YEAR FOR THE HUMBOLDT
BAY REGION. ELSEWHERE, CLEAR SKIES IN THE INTERIOR HAVE GENERALLY
ALLOWED FOR HIGHS IN THE LOW 80S.
LOW PRESSURE WILL GRADUALLY FILL IN AND DEEP TROUGH DIPPING ACROSS
THE EASTERN PACIFIC WILL GRADUALLY COME TO DOMINATE THE WEATHER
PATTERN WEDNESDAY THROUGH THE END OF THE WEEK. FLOW SWITCHING
ONSHORE AND MORE MARINE AIR WILL GENERALLY ALLOW FOR A MARINE LAYER
TO REFORM ALONG SHORE BY WEDNESDAY EVENING. EVEN WITH SKIES STAYING
MOSTLY CLEAR, ONSHORE FLOW WILL MOST LIKELY ALLOW FOR COASTAL HIGHS
TO RETURN TO THE 60S. WEAKENING HIGH PRESSURE WILL ALSO ALLOW THE
INTERIOR TO COOL BACK INTO THE 70S WEDNESDAY. BUILDING MIDLEVEL
CLOUDS WILL AID IN FURTHER COOLING THURSDAY.
AS THE TROUGH MOVE INLAND AROUND FRIDAY, TROPICAL MOISTURE PULLED IN
FRONT OF THE TROUGH WILL ENABLE AT LEAST LIGHT RAIN ACROSS THE AREA.
RAIN AMOUNTS REMAIN UNCERTAIN. DETERMINISTIC MODELS SHOW ONLY
MARGINAL (0.6 TO 0.8 IN) PRECIPITABLE WATER AMOUNTS. STILL,
CONSISTENT STRONG SOUTHWEST FLOW ALOFT MAY HELP MAKE UP FOR MARGINAL
AMOUNTS THANKS TO CONSISTENT MOISTURE TRANSPORT AND OROGRAPHIC
FORCING. NBM GENERALLY SEEMS TO BE ERRING ON THE HIGH END OF GLOBAL
ENSEMBLES WITH A WIDE SPREAD OF GENERALLY 0.5 AND 1.5 INCHES OF RAIN
ALONG THE NORTH COAST, MOST LIKELY BEGINNING EARLY FRIDAY MORNING.
GENERALLY LESS THAN 0.5 INCHES OF RAIN IS MOST LIKELY FOR THE
SOUTHERN HALF OF THE AREA WITH A 25% CHANCE OF NO PRECIPITATION AT
ALL.
LIGHTER RAIN SHOWERS WILL CONTINUE INTO THE WEEKEND WITH ONLY A 30%
CHANCE OF ADDITIONAL WETTING RAIN EACH SATURDAY AND SUNDAY. EVEN
WITHOUT RAIN, COOLER AND MORE MOIST CONDITIONS ARE LIKELY TO PERSIST
INTO EARLY NEXT WEEK WITH A GOOD CHANCE IF WIDESPREAD INTERIOR FROST
SHOULD CONDITIONS DRY OUT FAST ENOUGH BY SUNDAY AND MONDAY. /JHW
AVIATION...(18Z TAFS)
CLEAR SKIES WITH LIGHT AND VARIABLE WINDS
CONTINUED AT ALL FORECAST AERODROMES TODAY. STRATUS AND PERHAPS FOG
MAY START TO FILL IN OVER NORTH COAST AERODROMES LATE TONIGHT AS A
NORTHERLIES INCREASE OVER THE WATERS AFTER PASSAGE OF A WEAK FRONT.
ALSO, HIGHER HUMIDITY WITH LIGHT ONSHORE BREEZES THIS EVENING MAY
YIELD SHALLOW FOG AT THE TERMINALS LATE THIS EVENING AND OVERNIGHT.
HREF PROBABILITIES FOR 1/2SM OR LESS IN FOG TREND MUCH HIGHER
TONIGHT INTO EARLY MORNING WED AT BOTH KACV AND KCEC, PEAKING AROUND
50% BY 11-15Z. OTHERWISE, GENERALLY VFR CONDITIONS ARE EXPECTED TO
PREVAIL EXCEPT FOR IFR OR LIFR CONDITIONS ALONG THE MENDOCINO COAST.
MARINE
LIGHT AND VARIABLE WINDS TO 10 KT OR LESS CONTINUED
TODAY. A NORTHERLY WINDS WILL INCREASE LATE TONIGHT INTO WED BEHIND
A WEAK FRONT FORECAST TO PASS IN PAC NW ON WED. GREATEST COVERAGE
FOR GUSTS TO 25-30KT IS OVER THE OUTER WATERS. GUSTS TO 30KT WILL BE
POSSIBLE (40-60% CHANCE) INSIDE 10NM AND DOWNWIND OF CAPE MENDOCINO.
CHANCES ARE ARE LOWER (10-20%) AROUND PT ST GEORGE. STEEP NORTHERLY
WIND WAVES WILL ALSO REBUILD TO 6 TO 8 FT BY WED AND SEAS WILL ONCE
AGAIN BECOME HAZARDOUS TO SMALL CRAFT. NORTHERLIES WILL DIMINISH AND
EVENTUALLY TURN SOUTHERLY FOR THE NORTHERN WATERS ON THU.
SOUTHERLIES WILL LIKELY STRENGTHEN IN ADVANCE OF A FRONT ON FRIDAY.
NBM PROBABILITIES ARE NOT VERY HIGH AROUND 15 TO 25% FOR GUSTS OVER
25 MPH. LOOKING AT THE DETERMINISTIC GUIDANCE, SUSPECT THERE WILL BE
HIGHER GUSTS. LACK OF A LONG SOUTHERLY FETCH MAY LIMIT THE SHORT
PERIOD WAVE GENERATION TO ONLY 4 TO 5 FT FROM THE SW. THERE ARE
INDICATIONS FROM THE GEFS AND ECMWF ENS FOR STRONGER NORTHERLIES TO
RAMP UP TOWARD THE LATTER PORTION OF THE WEEKEND.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY FROM 6 AM WEDNESDAY TO MIDNIGHT PDT
WEDNESDAY NIGHT FOR PZZ470-475.
NOTE: THE FULL FORECAST DISCUSSION IS NOW REGULARLY ISSUED BETWEEN
10 AM/PM AND 1 PM/AM. ADDITIONAL UPDATES WILL BE ISSUED AS NEEDED.
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