308
FXUS66 KEKA 062325
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
425 PM PDT TUE OCT 6 2026
KEY MESSAGES
* A FEW MORE DAYS OF HIGH TEMPERATURES WITH BRING MODERATE
HEATRISK ACROSS THE INTERIOR THROUGH THE WEEK.
* A DEVELOPING TROUGH WILL BRING MUCH COOLER CONDITIONS BY FRIDAY
AND THE WEEKEND.
* NOT MUCH PRECIPITABLE RAIN EXPECTED OTHER THAN DRIZZLE.
SYNOPSIS
AN UPPER LEVEL TROUGH ALONG WITH ISOLATED LOW
PRESSURE AREAS FROM THE SOUTH WILL BREAKDOWN THE PERSISTENT UPPER
LEVEL RIDGE PATTERN BY THE END OF THE WEEK. A FEW MORE MORNINGS OF
DENSE FOG ARE LIKELY UNTIL THE TROUGH SWINGS DOWN FROM B.C. AND
INTERRUPTS THE STABLE LAYER INVERSION.
DISCUSSION
AS THE WORK WEEK PROGRESSES, THE STRONG AREA OF HIGH
PRESSURE THAT HAS KEPT A HEATRISK ADVISORY IN PLAY FOR THE SOUTHERN
AREAS OF THE CWA, WILL GET A REPRIEVE AS THE HIGH PRESSURE OVER THE
FOUR CORNERS GETS OVERWHELMED. SEVERAL LOW PRESSURE AREAS FROM THE
ACTIVE ENSO EQUATORIAL REVERSAL, APPROACH FROM THE SOUTHEASTERN
PACIFIC. THIS UPCOMING SET UP WILL HAVE THESE LOWS ABSORBED INTO THE
UPPER WAVE TROUGH WHICH WILL BE STRETCHING DOWN THE WEST COAST AT
THE END OF THE WEEK - FRIDAY AND SATURDAY, ACCORDING TO THE ECMWF
AND GFS. DESPITE PLENTY OF MOISTURE BEING SOURCED, THERE ARE'NT
ANY SIGNS OF PRECIPITABLE AMOUNTS GREATER THAN A FEW HUNDREDTHS
OF AN INCH FOR OUR AREA IN THE NEXT SEVERAL DAYS OTHER THAN
OCCASIONAL DRIZZLE OR CONDENSED LOW CLOUD VAPOR FROM OVERNIGHT
COOLING DYNAMICS.
OTHERWISE, THERE IS A DEFINITE DROP OFF IN TEMPERATURES FROM
THURSDAY TO FRIDAY AND EVEN MORE OF A DIMINISH OF DAYTIME HIGH
TEMPERATURES INTO THE WEEKEND. THE PREVIOUSLY MENTIONED AREAS OF
LOW PRESSURE BEGIN TO INTERACT WITH THE UPPER WAVE PATTERN FRIDAY
MORNING AS THE LARGER UPPER TROUGH AMPLIFIES OVER BRITISH COLUMBIA
BRINGING COOLER AIR MASSES WITH THE FRONTAL BOUNDARY. CHANCES FOR
ANY RAIN ARE LESS THAN 10% AND, IF ANYTHING, WOULD MANIFEST IN
ENHANCED COASTAL DRIZZLE. THIS INSIDE SLIDER PATTERN WOULD STILL
BRING MUCH COOLER TEMPERATURES WITH HIGHS THIS WEEKEND 10 TO 20
DEGREES COOLER. LOW TEMPERATURES ALSO HAVE HIGH CHANCES TO BE THE
COLDEST YET OF THE FALL WITH 20 TO 50% CHANCES FOR FREEZING
TEMPERATURES THIS WEEKEND INTO EARLY NEXT WEEK IN THE COLDEST
VALLEYS OF TRINITY AND EASTERN MENDOCINO COUNTIES.
ALONG WITH THE COOLER TEMPERATURES, BREEZY NORTHERLY WINDS ARE ALSO
BECOMING MORE LIKELY, ESPECIALLY ALONG THE COAST. NBM IS SHOWING 30%
CHANCES FOR GUSTS OVER 40 MPH ON THE HUMBOLDT AND DEL NORTE COASTS
ON SATURDAY, WITH LOCALLY HIGHER PROBABILITIES OVER THE KING RANGE
AND MOUNTAINS OF DEL NORTE. CHANCES FOR GUSTS OVER 30 MPH ARE MUCH
HIGHER AND MORE WIDESPREAD AT 70% ALONG THE COAST AND 20-50% FOR
MUCH OF THE INTERIOR. WHILE WINDS ARE LIKELY TO BE STRONGEST
SATURDAY, BREEZY WINDS ARE LIKELY AGAIN SUNDAY.
AS OF NOW, THE EXTENDED FORECAST REMAINS DRY. LONG RANGE ENSEMBLES
SHOW LITTLE CHANCE FOR ANY PRECIPITATION WITH MUCH OF THE STORM
TRACK MOVING NORTH OF THE AREA. CPC ALSO HAS HIGH CHANCES FOR BELOW
NORMAL PRECIPITATION IN THE 8-14 DAY OUTLOOK.
AVIATION...18Z TAFS
A VERY SHALLOW MARINE LAYER CONTINUES TO
IMPACT THE COASTAL TERMINALS. VISIBILITIES LOWERED TO LESS THAN
1/4SM AT TIMES FROM THE SHALLOW STRATUS. DAYTIME HEATING IS ALLOWING
FOR SCATTERING AND IMPROVEMENT AT ACV AND CEC, BUT AT LEAST TEMPO
PERIODS OF FOG AND LIFR CONDITIONS ARE POSSIBLE AS LIGHT NW WINDS
POOL THE STRATUS AGAINST THE COAST, PARTICULARLY AROUND HUMBOLDT BAY
AND ACV. EXPECT LIFR CONDITIONS AND FOG TO QUICKLY REDEVELOP
THROUGH THE LATER AFTERNOON AND EVENING HOURS FOR THE COASTAL AREAS.
THE FOG IS EXPECTED TO BECOME LOCALLY DENSE ONCE AGAIN, WITH
VISIBILITIES THAN THAN 1/4SM. THE INTERIOR WILL REMAIN VFR WITH
GENERALLY LIGHT WINDS.
MARINE
NORTH WINDS REMAIN ELEVATED IN THE OUTER WATERS TODAY WITH
WIDESPREAD SUSTAINED WINDS OF 15 KT TO 20KTS. SEAS STEEPEN IN
RESPONSE TO THESE WINDS BRINGING COMBINED SEAS OF 6 TO 10 FT ACROSS
THE WATERS, INCLUDING IN THE NEARSHORE WATERS WHERE WINDS REMAIN
MUCH LIGHTER. AREAS OF DENSE FOG WITH VISIBILITIES AT TIMES LESS
THAN 1/4 MILES WILL REMAIN OVER THE WATERS SEAS REMAIN DOMINATED BY
THESE WIND WAVES THROUGH THE WEEK WITH ONLY SMALL SOUTH-
SOUTHWESTERLY MID PERIOD SWELLS IN ADDITION TO THE WIND WAVES. WINDS
BEGIN TO EASE WEDNESDAY, ESPECIALLY IN THE SOUTHERN WATERS, AS HIGH
PRESSURE STRENGTHENS FURTHER. STRONGER NORTHERLIES RETURN FRIDAY
INTO THE WEEKEND. WIDESPREAD GALE FORCE GUSTS TO AREAS OF SUSTAINED
GALE STRENGTH WINDS ARE LIKELY THIS WEEKEND. STORM FORCE GUSTS ARE
POSSIBLE IN THE LEE OF CAPE MENDOCINO.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
HEAT ADVISORY UNTIL 11 PM PDT THURSDAY FOR CAZ110>114-
118>120.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR
PZZ450.
SMALL CRAFT ADVISORY UNTIL 4 PM PDT WEDNESDAY 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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