323
FXUS66 KEKA 140700
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
1200 AM PDT SUN SEP 14 2025
SYNOPSIS
A QUICK MOVING COLD FRONT BRINGS A QUICK CHANCE FOR RAIN
AND THUNDERSTORMS EARLY THIS MORNING. CLEARING SKIES AND DRY
CONDITIONS EXPECTED FOR THE REST OF THE DAY. A WARMING TREND RETURNS
TO THE INTERIOR STARTING MONDAY THROUGH MID NEXT WEEK.
DISCUSSION
A WEAK COLD FRONTAL SYSTEM HAS REACHED THE AREA EARLY
THIS MORNING, BRINGING A FEW SHOWERS TO HUMBOLDT AND DEL NORTE
COUNTIES. COLDER AIR ALOFT WILL CONTINUE THE THREAT OF ISOLATED
THUNDERSTORMS THROUGH THE SUNRISE HOURS OVER THE COASTAL WATERS, DEL
NORTE, AND NORTHERN HUMBOLDT. THE MAIN THREAT OTHER THAN LIGHTNING
WILL BE PERIODS OF MODERATE TO HEAVY RAIN. HREF IS SHOWING UP TO 40%
CHANCE FOR RAIN RATES OF OVER 0.25 INCHES AN HOUR IN DEL NORTE, WITH
CHANCES FALLING BELOW 10% SOUTH OF DEL NORTE COUNTY. PROBABILITIES
OF MORE THAN A 0.25 INCHES IN AN HOUR DROP OFF CONSIDERABLY, WITH
THE ENSEMBLE MAX PEAKING AT AROUND 0.5 INCH AN HOUR. IN TERMS OF
TOTAL RAIN AMOUNTS, THE OFFICIAL FORECAST IS AROUND 0.10 TO 0.30
INCHES IN DEL NORTE AND LESS THAN A TENTH IN NORTHERN HUMBOLDT, WITH
LITTLE TO NO ACCUMULATIONS TO THE SOUTH AND EAST.
RAIN CHANCES DIMINISH AFTER SUNRISE AND, GENERALLY, A DRY, SUNNY DAY
IS LIKELY ACROSS THE AREA. INTERIOR HIGH TEMPERATURES MAY FALL A FEW
DEGREES COMPARED TO SATURDAY, WITH MOST INTERIOR VALLEYS SEEING HIGH
70'S TO THE MID 80'S. WITH LIGHT WINDS THIS MORNING AND CLEARING
SKIES AT THE COAST, HIGH TEMPERATURES MAY SPIKE INTO THE MID TO HIGH
60'S ONCE AGAIN AS HIGH PRESSURE BEGINS TO BUILD BACK IN. BREEZY
NORTHERLY WINDS ARE FORECAST TO DEVELOP, MOSTLY COASTAL AREAS, AS
THE SURFACE PRESSURE GRADIENT TIGHTENS THIS AFTERNOON AND EVENING.
NBM PROBABILITIES INDICATE A 50-80% CHANCE FOR WIND GUSTS GREATER
THAN 25 MPH OVER THE EXPOSED RIDGES AND COASTAL HEADLANDS THIS
AFTERNOON. ALSO, GUSTY WEST-NORTHWEST WINDS WILL MOST LIKELY DEVELOP
THROUGH CHANNELED TERRAIN IN THE INTERIOR THIS AFTERNOON/EVENING.
MONDAY, 850MB TEMPERATURES WILL BEGIN TO INCREASE AS THE UPPER-LEVEL
HEIGHTS RISE ACROSS THE WEST COAST. THIS WILL BRING A WARMING TREND
EARLY TO MID NEXT WEEK, WITH THE DRIEST/WARMEST DAY MOST LIKELY ON
TUESDAY. BOTH TONIGHT INTO MONDAY AND MONDAY NIGHT INTO TUESDAY,
BREEZY OFFSHORE WINDS ARE EXPECTED OVER THE RIDGES OVER THE EASTERN
PORTION OF THE FORECAST AREA, PARTICULARLY IN THE MOUNTAINS OF DEL
NORTE. INTERIOR VALLEYS ARE FORECAST REBOUND TO THE MID TO UPPER
90'S BY TUESDAY. THE RIDGE BEGINS TO WEAKEN AND MOVE EASTWARD BY
WEDNESDAY AND THURSDAY AS A TROUGH APPROACHES THE PACIFIC NORTHWEST.
SOME ENSEMBLE MEMBERS ARE SHOWING A CUTOFF LOW FORMING OVER THE
COAST OF CALIFORNIA, WHICH COULD RETURN MONSOONAL MOISTURE TO THE
AREA. THE ARRANGEMENT OF THE PACIFIC NORTHWEST TROUGH AND THE LOW
OVER THE COAST OF CALIFORNIA ARE BOTH UNCERTAIN, SO CONFIDENCE IS
LOW ON ANY IMPACTS. IF IT DOES END UP ON THE WETTER END (~25% OF
ENSEMBLE MEMBERS), SHOWERS AND THUNDERSTORMS ARE POSSIBLE FOR THE
INTERIOR AREAS. STAY TUNED. JB
AVIATION...(06Z TAFS)
THE INFLUENCE OF A COLD FRONT PASSING
OVER THE PACNW HAS WEAKENED THE MARINE LAYER INVERSION ALONG THE
COAST GIVING WAY TO VFR CATEGORIES AND ELEVATED SCATTERED SKIES.
CONVECTIVE CLOUDS ARE CURRENTLY SEEN ON DOPPLER RADAR OVER THE NORTH
COAST. THESE CLOUDS WILL EVOLVE INTO SHORT-LIVED RAINSHOWERS AS THEY
MIGRATE OVER TERMINALS THROUGH TOMORROW. HREF AND NBM DATA SHOWS A
CHANCE (~30%) FOR THE OCCASIONAL THUNDERHEAD, CURRENTLY SEEN
OFFSHORE OF CAPE BLANCO, TO PASS OVER KCEC TONIGHT. GUSTY NORTHWEST
WINDS IN THE AFTERNOON AS 925MB WINDS ARE EXPECTED BETWEEN 20-30KTS
FOR COASTAL MENDOCINO. INLAND AREAS WILL REMAIN VFR THROUGH THE
NIGHT WITH SCATTERED CLOUDS ALOFT AND LIGHT WINDS TONIGHT WITH
DIURNAL WINDS AND THE OCCASIONAL AFTERNOON WEAK GUST (<20KTS) AS
ELEVATED WINDS MIX DOWN TO THE SURFACE.
MARINE
A SHORTWAVE TROUGH HAS CREATED A CONTINUATION FOR
THE CHANCE FOR THUNDERSTORMS OVER THE NORTHERN WATERS. DOPPLER RADAR
AND SATELLITE DATA REPORTS LIGHTNING ALREADY OFF THE COAST OF CAPE
BLANCO, WHICH COULD MIGRATE SOUTHWARD THROUGH THE NIGHT. WIND SPEEDS
ARE EXPECTED TO BE GENTLE BREEZES WITH SMALL WIND WAVES. A NW SWELL
OF 5FT@12S WILL DOMINATE THE WATERS BEFORE HIGH PRESSURE SLOWLY
RETURNS BEGINNING MONDAY. STRONG WINDS AND STEEP WIND WAVES HAVE
CALLED FOR A SMALL CRAFT ADVISORY FOR THE OUTER WATERS SUNDAY
EVENING UNTIL MONDAY AFTERNOON. THESE WINDS DUE TO HIGH PRESSURE
WILL BE SHORT LIVED AND ARE TO BACK DOWN TUESDAY. CONDITIONS AT THE
END OF THIS COMING WORK WEEK ARE FORECAST TO HAVE STRONG NORTHERLY
WINDS AND LARGE WIND WAVES, BUT MODELS ARE NOT CONFIDENT ON THE
EXTENT OF THE WIND SPEED AS OF RIGHT NOW. MORE TO COME.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY FROM 11 PM SUNDAY TO 5 PM PDT MONDAY
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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