918
FXUS66 KEKA 120829
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
129 AM PDT FRI SEP 12 2025
SYNOPSIS
DRIER AND WARMER CONDITIONS TODAY AND SATURDAY,
FOLLOWED BY A PERIOD OF MORE LIGHT RAIN FOR THE NORTH COAST ON
SUNDAY. THE SYNOPTIC WEATHER PATTERN TRENDING WARMER AND DRIER
EARLY NEXT WEEK.
DISCUSSION
AN SHORTWAVE RIDGE HAS BEGUN TO BUILDS INTO THE
WEST COAST DOWNSTREAM OF THE PASSED LO PRESSURE SYSTEM. MEANWHILE,
A DEEPER MARINE LAYER HAS PUSHED WELL INLAND OVERNIGHT. THE
MCKINLEYVILLE (ACV) PROFILER DATA IS SHOWING A MARINE LAYER DEPTH
UP TO AROUND 3000 FEET. AS A RESULT, THE STRATUS COVERED ENTIRELY
DEL NORTE AND HUMBOLDT COUNTIES. MEANWHILE, A SHALLOW MARINE
LAYER HAS DEVELOPED ALONG THE MENDOCINO COAST.
THE AFOREMENTIONED RIDGE WILL MOVES OVER THE AREA TODAY THROUGH
SATURDAY, PROMOTING DRIER AIRMASS AND WARMER TEMPERATURES ACROSS
THE INTERIOR. EXPECT SUNNY SKY ACROSS MUCH OF THE FORECAST AREA,
BUT MOSTLY CLOUDY DAY ALONG THE NORTH COAST WITH PERSISTENT
COASTAL STRATUS. INTERIOR HIGH TEMPERATURES ARE FORECASTED TO BE
IN THE UPPER 70'S TO UPPER 80'S TODAY AND SATURDAY. ONSHORE FLOW
WILL REMAIN THE COASTAL AREAS THE AFTERNOON TEMPERATURES IN THE
LOW TO MID 60'S.
THE RIDGE ALOFT SHIFT EASTWARD ON SATURDAY, AS A WEAK H5 TROUGH
APPROACHES THE PACIFIC NORTHWEST. AN ASSOCIATED WEAK COLD FRONT
ASSOCIATED WILL MOVES EAST-SOUTHEAST ACROSS NORTHERN CALIFORNIA
LATE SATURDAY NIGHT. THIS WILL BRING A PUSH LOW LEVEL MOISTURE
AND PERHAPS SOME LIGHT RAIN MAINLY ALONG THE COASTAL RANGE IN DEL
NORTE AND NORTHERN HUMBOLDT COUNTIES LATE SATURDAY NIGHT THROUGH
THE DAY ON SUNDAY. OTHERWISE, DRY WEATHER AND SOME COOLING OF
INTERIOR HIGH TEMPS ARE EXPECTED.
SURFACE HIGH PRESSURE WILL BUILD IN QUICKLY OVER THE REGION ON
SUNDAY IN THE WAKE OF THE FRONT. BREEZY NORTHERLY WINDS ARE
FORECAST TO DEVELOPED OVER MOSTLY COASTAL AREAS AS SURFACE
PRESSURE GRADIENTS TIGHTEN SUNDAY EVENING. NBM PROBABILITIES
INDICATES 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.
HIGH PRESSURE BEGINS TO BUILD ACROSS THE WEST COAST ON MONDAY.
THIS WILL BRING A WARMING TREND EARLY THROUGH MID NEXT WEEK.
850MB TEMPERATURE ANALYSIS SHOWS INTERIOR VALLEYS REACHING OR
EXCEEDING 90'S DEGREES ON MONDAY WITH WARMING INTO THE UPPER 90'S
THROUGH MID NEXT WEEK ACROSS THE WARMER LOCATIONS OF TRINITY,
LAKE, INTERIOR MENDOCINO, AND INTERIOR HUMBOLDT COUNTIES. /ZVS
AVIATION...(6Z TAFS)
IFR TO MVFR CONDITIONS ARE BEING OBSERVED AT
THE COASTAL TERMINALS, AND THIS IS LIKELY TO CONTINUE THROUGH THE
NIGHT. THE MARINE LAYER REMAINS DEEP AND IS KEEPING CEILINGS
ELEVATED. GENERALLY CEILINGS WILL FALL EARLY FRIDAY, BUT UNCERTAINTY
IS HIGH ON HOW LOW. AT CEC, NBM IS SHOWING ABOUT A 70% FOR LIFR
CEILINGS BEFORE SUNRISE. WORSENING VISIBILITIES ARE POSSIBLE TOO,
BUT ARE LESS LIKELY. AT ACV, THE CLOUD BASE IS AROUND 1000 FT HIGHER
THAN AT CEC. STILL, NBM IS SHOWING AROUND A 60% FOR LIFR CEILINGS
BEFORE SUNRISE. CONFIDENCE IS LOWER HERE AS CEILINGS ARE ALREADY
HIGHER THAN MODELED, BUT IFR CEILINGS ARE CERTAINLY POSSIBLE. UKI IS
LIKELY TO REMAIN CLEAR TONIGHT DESPITE THE DEEPER MARINE LAYER. IF
THERE ARE ANY IMPACTS, IT WOULD BE BRIEF AROUND SUNRISE, AND AND
CLOUDS WILL LIFT AND SCATTER SHORTLY AFTER SUNRISE. AT THE COAST,
STRATUS IS LIKELY TO REMAIN IN PLACE THROUGH THE DAY, BUT CEILINGS
WILL LIKELY LIFT TO IFR OR MVFR. REGARDLESS, STRATUS WILL MAKE A
RETURN IN THE EVENING AND OVERNIGHT. JB
MARINE
NORTHERLIES CONTINUE TODAY, WITH WINDS PEAKING LATE
MORNING AND EARLY AFTERNOON. GUSTS OF 20-25 KTS POSSIBLE IN THE
OTHER WATERS AND LOCALLY STRONGER GUSTS OF 30-35 KTS POSSIBLE AROUND
CAPE MENDOCINO. NEARSHORE WINDS GENERALLY REMAIN LIGHT. WINDS AND
SEAS EASE TONIGHT THROUGH SUNDAY AS AN AREA OF LOW PRESSURE MOVES TO
THE NORTH OF THE AREA. NORTHERLIES WILL INCREASE AGAIN LATER SUNDAY
THROUGH MONDAY AS HIGH PRESSURE BUILDS BACK IN. THE LOCAL PRESSURE
GRADIENT WILL BE FURTHER STRENGTHENED BY AN AREA OF LOW PRESSURE
FARTHER NORTH OVER THE PACIFIC NORTHWEST. NBM CURRENTLY HOLDS A
GREATER THAN 50% CHANCE FOR GALE STRENGTH GUSTS OVER MAINLY THE
SOUTHERN WATERS LATE SUNDAY THROUGH MONDAY.
SEAS ARE MOSTLY CHARACTERIZED BY BUILDING SHORT PERIOD WIND WAVES,
WHICH WILL BE STEEP AND HAZARDOUS TO SMALL CRAFTS. DESPITE LIGHTER
WINDS, STEEP SEAS ARE FORECAST TO PROPAGATE TO THE NEARSHORE WATERS
OF MENDOCINO THIS MORNING AND EARLY AFTERNOON. A LONG PERIOD NW
SWELL CONTINUES TO FILL IN, WHICH, COMBINED WITH THE WIND WAVES OF 6-
8 FT, RESULTS IN COMBINED SEAS OF 7-10 FT TONIGHT. SEAS ARE FORECAST
TO EASE SATURDAY INTO EARLY SUNDAY AS WINDS EASE, BUT ANOTHER MID-
PERIOD NW SWELL OF AROUND 5-7 FT IS FORECAST TO FILL IN SUNDAY,
KEEPING SEAS ELEVATED. ALONG WITH BUILDING SHORT PERIOD WIND WAVES,
COMBINED SEAS MAY EXCEED 10 FT. JB
BEACH HAZARDS
A BEACH HAZARD STATEMENT IS IN EFFECT THROUGH
8 AM PDT THIS MORNING DUE TO A MODERATE RISK OF SNEAKER WAVES
ALONG AREAS BEACHES IN DEL NORTE AND HUMBOLDT COUNTIES. A LONG
PERIOD WNW SWELL CONTINUES MOVING ACROSS THE WATERS OVERNIGHT,
WITH HEIGHTS AT 4-5 FEET AT 16-17 SECONDS THIS MORNING. THESE
LONG PERIOD WAVES CAN GENERATE LULLS IN WAVE ACTIVITY ENDING WITH
A LARGE SET OF BREAKING WAVES THAT WASH MUCH FARTHER UP BEACH THAN
PREVIOUS WAVES. DON'T BE FOOLED BY AN OCEAN THAT LOOKS CALM.
THERE CAN BE 30 MINUTES OF SMALL WAVES BEFORE A SNEAKER WAVE
STRIKES. AVOID ROCKS AND JETTIES. AVOID STEEP BEACHES. STAY MUCH
FARTHER BACK FROM THE WATER AND NEVER TURN YOUR BACK ON THE
OCEAN. /ZVS
EKA WATCHES/WARNINGS/ADVISORIES
CA...
BEACH HAZARDS STATEMENT UNTIL 8 AM PDT FRIDAY FOR CAZ101-
103-104.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 11 AM PDT SATURDAY FOR PZZ455.
SMALL CRAFT ADVISORY UNTIL 11 PM PDT FRIDAY FOR PZZ470.
SMALL CRAFT ADVISORY UNTIL 11 AM PDT SATURDAY FOR PZZ475.
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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