332
FXUS66 KEKA 140014
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
514 PM PDT SAT SEP 13 2025
AVIATION...(00Z TAFS)
THE INFLUENCE OF A COLD FRONT HAS WEAKENED
THE MARINE LAYER INVERSION ALONG THE COAST LEADING TO CLEAR TO
SCATTERED VFR SKIES. CONVECTIVE CLOUDS ARE CURRENTLY SEEN ON DOPPLER
RADAR APPROXIMATELY 60NM OFFSHORE FROM KCEC. THESE CLOUDS WILL
EVOLVE INTO RAINSHOWERS AS THEY MIGRATE OVER FAR NORTH COAST
TERMINALS TONIGHT AND TOMORROW MORNING WITH EVEN THE POSSIBILITY FOR
OCCASIONAL THUNDERSTORMS. INLAND AREAS WILL REMAIN VFR THROUGH THE
NIGHT WITH SCATTERED CLOUDS ALOFT AND LIGHT WINDS THE AFTERNOON.
KUKI MAY SEE BRIEF GUSTY NORTHWEST WINDS IN THE AFTERNOON AS 925MB
WINDS ARE EXPECTED BETWEEN 20-30KTS FOR SOUTHERN MENDO. AND LAKE
COUNTIES.
PREV DISCUSSION
/ISSUED 132 PM PDT SAT SEP 13 2025/
SYNOPSIS...DRY WEATHER WITH SEASONABLY AVERAGE TEMPERATURES
CONTINUE THIS AFTERNOON, BEFORE A PROGRESSIVE TROUGH BRINGS A CHANCE
OF SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS LATE TONIGHT THROUGH
SUNDAY MORNING. THE DRYING AND WARMING TREND RETURNS ON MONDAY,
CONTINUING THROUGH MID NEXT WEEK.
DISCUSSION...STRATUS CONTINUES TO LIFT AND ERODE BACK TOWARD THE
COAST THIS AFTERNOON WITH THE DAYTIME HEATING. STRATUS FOR COASTAL
LOCATIONS MAY PERSIST WITH THE GENTLE SEA BREEZE.
SHORTWAVE HIGH PRESSURE CONTINUES TO SHIFT EASTWARD TODAY, WHILE
A WEAK H5 TROUGH AND ASSOCIATED COLD FRONT APPROACH THE PACIFIC
NORTHWEST. EXPECT ANOTHER DAY WITH DRY AND NEAR-SEASONAL AVERAGE
TEMPERATURES. INLAND HIGH TEMPERATURES ARE FORECAST TO BE IN THE
UPPER 70'S TO UPPER 80'S IN THE INTERIOR VALLEYS AND MID 60'S TO
MID 70'S OVER THE FOOTHILLS. COASTAL AREAS WILL REMAIN UNDER
MARINE INFLUENCE WITH HIGHS IN THE LOW TO MID 60'S. WINDS WILL
LIKELY INCREASE FROM THE NORTHWEST THIS AFTERNOON AND EVENING
ALONG THE COAST AND EXPOSED RIDGES, BECOMING GUSTY AT TIMES,
ESPECIALLY FOR MENDOCINO AND LAKE COUNTIES. SOUTHWEST WINDS ALOFT
WILL BRING INCREASING MID TO HIGH LEVEL MOISTURE LATE THIS
AFTERNOON AND EVENING AHEAD OF THE APPROACHING FRONTAL SYSTEM.
THE PROGRESSIVE AFOREMENTIONED TROUGH AND ASSOCIATED COLD FRONT WILL
BRING A CHANCE OF SHOWERS ACROSS THE COAST AND COASTAL RANGES LATE
TONIGHT THROUGH SUNDAY MORNING, MAINLY IN DEL NORTE AND NORTHERN
HUMBOLDT COUNTIES. ALSO, INCREASING INSTABILITY WITH COLD AIR ALOFT
WILL PROMOTE A THREAT OF ISOLATED THUNDERSTORMS AND BRIEF HEAVY
DOWNPOURS LATE TONIGHT INTO EARLY SUNDAY. CONVECTIVE ALLOWING MODELS
(CAMS) INDICATE LOCALIZED STRONG SIMULATED CORES GREATER THAN 45DBZ
OVER DEL NORTE AND FAR NORTHERN HUMBOLDT LATE TONIGHT OR EARLY
SUNDAY. THE HREF GUIDANCE INDICATES A 50-60% CHANCE FOR RAIN RATES
OVER 0.25 INCHES PER HOUR WITH AN ENSEMBLE MAX OVER 0.50IN/HR LATE
TONIGHT INTO EARLY SUNDAY MORNING. ECMWF ENSEMBLE 75TH PERCENTILE 24-
HOUR TOTALS ARE UNDER 0.50 INCHES FOR DEL NORTE WITH ONE OR TWO
OUTLIERS OVER 1 INCH. RAW ECMWF PROBABILITIES FOR MORE THAN 0.50
INCHES IN 24 HOURS ARE 30-40%, PRIMARILY OVER COASTAL DEL NORTE NEAR
THE OR/CA BORDER. THUS, INSTABILITY AND DEEP MOIST CONVECTION
COULD YIELD MUCH HIGHER RAIN AMOUNTS. OFFICIAL 24-HOUR WPC QPF
RAINFALL TOTALS RANGE FROM 0.15 TO 0.35 INCHES IN DEL NORTE
COUNTY AND GENERALLY LESS THAN A TENTH FOR NORTHERN HUMBOLDT.
OTHER THAN LIGHT COASTAL DRIZZLE OR SPRINKLES, DRY WEATHER AND
SOME COOLING OF INTERIOR HIGH TEMPS ARE EXPECTED THROUGH THE DAY
ON SUNDAY.
HIGH PRESSURE WILL BEGIN TO BUILD IN QUICKLY OVER THE REGION ON
SUNDAY IN THE WAKE OF THE FRONT. BREEZY NORTHERLY WINDS ARE
FORECAST TO DEVELOP OVER MOSTLY COASTAL AREAS AS THE SURFACE
PRESSURE GRADIENT TIGHTENS SUNDAY EVENING. NBM PROBABILITIES
INDICATE A 50-80% CHANCE FOR WIND GUSTS GREATER THAN 25 MPH OVER
THE EXPOSED RIDGES AND COASTAL HEADLANDS ON SUNDAY. ALSO, GUSTY
WEST-NORTHWEST WINDS WILL MOST LIKELY DEVELOP THROUGH CHANNELED
TERRAIN IN THE INTERIOR BEHIND THE FRONT SUNDAY AFTERNOON/EVENING.
MONDAY, 850MB 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. MONDAY NIGHT INTO TUESDAY, BREEZY OFFSHORE WINDS ARE
EXPECTED OVER THE RIDGES ACROSS THE EASTERN PORTION OF THE
FORECAST AREA. INTERIOR VALLEYS ARE FORECAST TO BE IN THE MID TO
UPPER 90'S BY TUESDAY ACROSS THE WARMER LOCATIONS OF TRINITY,
LAKE, INTERIOR MENDOCINO, AND INTERIOR HUMBOLDT COUNTIES. /ZVS
AVIATION...(18Z TAFS)...IFR TO MVFR CEILINGS ARE OSCILLATING
AT THE COASTAL TERMINALS. MVFR BROKEN CEILINGS ARE EXPECTED TO FORM
THIS AFTERNOON AS THE INFLUENCE OF A COLD FRONT WEAKENS THE MARINE
LAYER INVERSION. SOME SCATTERING IS POSSIBLE, BUT IT WOULD BE BRIEF
BEFORE STRATUS RETURNS OVERNIGHT. CONVECTIVE RAIN SHOWERS AND EVEN A
POSSIBILITY FOR THUNDERSTORMS LATE TONIGHT INTO SUNDAY MORNING FOR
NORTHERN TERMINALS. INLAND AREAS WILL REMAIN VFR THROUGH THE DAY
WITH SCATTERED CLOUDS ALOFT AND LIGHT WINDS THE AFTERNOON. KUKI MAY
SEE BRIEF GUSTY NORTHWEST WINDS IN THE AFTERNOON AS 925MB WINDS ARE
EXPECTED BETWEEN 20-30KTS FOR SOUTHERN MENDO. AND LAKE COUNTIES.
MARINE...A SHORTWAVE TROUGH WILL BRING A SLIGHT CHANCE FOR
THUNDERSTORMS OVER THE NORTHERN WATERS LATE SATURDAY AND INTO SUNDAY
MORNING. 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 RETURNS. THIS HIGH PRESSURE OFF SHORE AND LOW PRESSURE
INLAND WILL INCREASE THE NORTHERLY WINDS LATE SUNDAY THROUGH MONDAY
BEFORE BACKING DOWN TUESDAY. STRONGER NORTHERLIES ARE POSSIBLE MID
TO LATE WEEK WITH SOME MODELS SHOWING CONDITIONS THAT COULD WARRANT
A GALE WARNING AND/OR HAZARDOUS SEA WARNING. MORE UPDATES TO COME.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
NONE.
NOTE: THE FULL FORECAST DISCUSSION IS NOW REGULARLY ISSUED BETWEEN
10 AM/PM AND 1 PM/AM. ADDITIONAL UPDATES WILL BE ISSUED AS NEEDED.
VISIT US AT HTTPS://WWW.WEATHER.GOV/EUREKA
FOLLOW US ON FACEBOOK AND TWITTER AT:
HTTPS://WWW.FACEBOOK.COM/NWSEUREKA
HTTPS://WWW.TWITTER.COM/NWSEUREKA
FOR FORECAST ZONE INFORMATION
SEE THE FORECAST ZONE MAP ONLINE:
HTTPS://WWW.WEATHER.GOV/IMAGES/EKA/ZONEMAP.PNG
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page