557
FXUS66 KEKA 222032
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
132 PM PDT WED OCT 22 2025
SYNOPSIS
SNEAKER WAVE AND LARGE SURF RISK CONTINUES THROUGH
THE WEEK. CONFIDENCE REMAINS HIGH FOR AN ATMOSPHERIC RIVER STORM
IMPACTING NORTHERN CALIFORNIA FRIDAY INTO THE WEEKEND. ADDITIONAL
RAINFALL IS FORECAST TO CONTINUE THROUGH SUNDAY AND POSSIBLY INTO
MONDAY.
KEY MESSAGES:
- RISK OF SNEAKER WAVES AND LARGE SURF CONTINUES THROUGH THE WEEK
AND INTO THE WEEKEND.
- ATMOSPHERIC RIVER ARRIVES TO THE AREA FRIDAY INTO THE WEEKEND,
BRINGING PERIODS OF MODERATE TO HEAVY RAIN.
- GUSTY SOUTH WINDS LIKELY AT TIMES FRIDAY AND SATURDAY, WITH THE
STRONGEST GUSTS ON EXPOSED RIDGES, COASTAL HEADLANDS, AND CHANNELED
TERRAIN.
- MOUNTAIN SNOW LIKELY, WITH SNOW LEVELS DROPPING AS LOW AS 4500 FT
SATURDAY NIGHT INTO SUNDAY.
DISCUSSION
HIGH PRESSURE HAS WEAKENED AS AN UPPER LOW TO OUR
SOUTH COMBINED WITH A WEAK COLD FRONT MOVING THROUGH THE AREA. HIGH
CLOUD COVER OVERNIGHT MODERATED TEMPERATURES SOMEWHAT AND KEPT ONLY
THE COLDEST VALLEYS IN THE 30S. COASTAL STRATUS HAS RETURNED AS A
DEEP MARINE LAYER, BRINGING STRATUS EVEN INTO THE INTERIOR VALLEYS
OF MENDOCINO, HUMBOLDT, AND DEL NORTE. THE WEAK COLD FRONT MAY BRING
SOME DRIZZLE TO THE DEL NORTE COAST, BUT OTHERWISE IMPACTS ARE
LIMITED TO JUST INCREASED CLOUD COVER AND SLIGHTLY LOWER
TEMPERATURES. EXPECT DAYTIME HIGHS INTO THE 70S FOR MUCH OF THE
INTERIOR VALLEYS AND HIGH 50S TO LOW 60S FOR THE COASTAL AREAS.
A DEEP AND EXPANSIVE ALEUTIAN LOW WILL DRIVE IN AN ATMOSPHERIC RIVER
TYPE SYSTEM INTO THE PACIFIC NORTHWEST FRIDAY. MULTIPLE DISTURBANCES
WILL ROTATE OFF THIS LOW, IMPACTING NORTHERN CA WITH THE ATMOSPHERIC
RIVER AND MODERATE TO HEAVY PRECIPITATION LATER FRIDAY INTO SUNDAY.
GUSTY SOUTHERLY WINDS ARE LIKELY WITH THESE SERIES OF STORMS. NBM
CONTINUES TO OUTLINE MODERATE TO HIGH CHANCES FOR PERIODS OF WIND
GUSTS OVER 40 MPH FOR PORTIONS OF DEL NORTE AND OVER THE KING RANGE.
CHANCES FOR WINDS GUSTS OF 30 TO 35 MPH ARE HIGH FOR OVER MOST OF
THE AREA, PARTICULARLY SATURDAY WHEN INSTABILITY ARRIVES WITH THE
PASSING OF THE COLD TROUGH. COASTAL THUNDERSTORMS ARE POSSIBLE
SATURDAY AFTERNOON INTO SUNDAY. THE HIGHER PRECIPITABLE WATER VALUES
WILL HAVE SHIFTED SOUTH AT THIS TIME; HOWEVER, COLD 500MB
TEMPERATURES (-22 TO -26C) WITH STEEP LAPSE RATES AND MODEST SURFACE
CAPE WILL CONTRIBUTE TO SOME LOCALLY HIGHER PRECIPITATION RATES FROM
COASTAL HUMBOLDT AND MAINLY DEL NORTE COUNTY.
PRECIPITATION RANGES FROM THE NBM (COMPARING THE 25TH AND 75TH
PERCENTILES) REMAIN REMARKABLY STABLE WITH 4-6 INCHES FORECAST FOR
DEL NORTE COUNTY, 1.5-4.0 INCHES FORECAST FOR HUMBOLDT AND TRINITY
COUNTIES. THE LARGEST VARIABILITY IS IN SOUTHERN MENDOCINO AND LAKE
WHERE THE RANGE IS JUST 0.25-1.5 INCHES. WITH THIS MUCH RAIN, RAPID
RISES IN SMALL STREAMS AND RIVERS, MINOR FLOOD IMPACTS TO URBAN
AREAS, AND DEBRIS ON ROADWAYS ARE ALL POSSIBLE. SNOW LEVELS ARE
INITIALLY FORECAST TO REMAIN HIGH, ABOVE 7000 FT, BUT TREND DOWNWARD
SATURDAY INTO SUNDAY MORNING, DROPPING AS LOW AS 4500 FT. SNOW
IMPACTS ARE POSSIBLE ALONG SCOTT MOUNTAIN PASS ON HIGHWAY 3 IN
TRINITY COUNTY SATURDAY AND SUNDAY, BUT THERE IS STILL SOME
UNCERTAINTY ON HOW COLD THIS SYSTEM WILL BE. CURRENTLY 1-3 INCHES
ARE FORECAST ABOVE 5000 FT, WHILE 6-12 INCHES ARE FORECAST ABOVE
7000 FT.
SOME MODELS ARE STARTING TO RESOLVE AN ADDITIONAL DISTURBANCE SUNDAY
THAT WILL MAY CONTAIN LIGHT TO MODERATE RAINFALL. FURTHER
PRECIPITATION AMOUNTS DON'T CURRENTLY LOOK IMPRESSIVE, BUT ANY
ADDITIONAL RAIN COULD STILL BE IMPACTFUL. ENSEMBLE CLUSTERS ARE
FAIRLY CONFIDENT ON SHORTWAVE RIDGING AND A BREAK FROM PRECIPITATION
ARISING BY TUESDAY, BUT CONFIDENCE ON THE PATTERN DIMINISHES
SIGNIFICANTLY BY MID NEXT WEEK. CPC IS HIGHLIGHTING OUR AREA AS
BEING IN SLIGHT RISK FOR HEAVY PRECIPITATION STARTING OCTOBER
29TH INTO EARLY NOVEMBER. JJW/JB
AVIATION...(18Z TAFS)
DECAYING FRONT APPROACHING THE NORTH COAST
HAS BEEN RESULTING IN MVFR CIGS FOR COASTAL TERMINALS THIS
AFTERNOON. CEILINGS SHOULD LIFTING UP THIS AFTERNOON, HOWEVER MOIST
AIR CONDITIONS BANKED UP AGAIN THE COASTAL RANGES WILL LIKELY RESULT
IN A RETURN OF MVFR CONDITIONS. IFR OR LIFR CIGS/VSBYS ARE CERTAINLY
POSSIBLE (20% CHANCE), HOWEVER CONFIDENCE REMAINS LOW WITH NOTABLE
DRY/CLEAR SLOT OFFSHORE AND LIGHT OFFSHORE BREEZES RETURNING. HIGH
LEVEL CIRRUS CLOUDS WILL CONTINUE TO SWEEP OVER UKI THIS EVENING AS
A CLOSED LOW OVER SOUTHERN CALIFORNIA EJECTS EASTWARD. VFR
CONDITIONS ARE EXPECTED WITH LOW CHANCES (10%) FOR MVFR CIGS OVER
UKI BY EARLY THU MORNING.
MARINE
A SERIES OF LARGE LONG PERIOD W TO NW SWELLS WILL IMPACT
NORTHWEST CALIFORNIA COASTAL WATERS AND SHORES THROUGH THIS WEEKEND.
FIRST SWELL GROUP THAT PEAKED LAST NIGHT WILL STEADILY SUBSIDE
TONIGHT THROUGH THU. LEADING EDGE OF THE NEXT SWELL GROUP WILL
ARRIVE THURSDAY AFTERNOON AND THEN BUILD TO 12 TO 14 FEET THU NIGHT
INTO FRI MORNING. THIS SWELL WILL ALSO BRING A RISK FOR SNEAKER
WAVES AND ABOVE NORMAL SURF TO THE WEST AND NORTHWEST FACING
BEACHES. SOUTHERLY WINDS AND STEEP S-SW WIND WAVES WILL INCREASE ON
FRIDAY IN ADVANCE OF A FRONTAL SYSTEM. SEAS WILL BECOME MUCH ROUGHER
WITH THE COMBINATION OF STEEP SOUTHERLY WIND WAVES ON TOP OF A 10+
FOOT NW SWELL ON FRI. THERE IS A CHANCE FOR GALE FORCE WIND GUSTS,
ABOUT 20-50% CHANCE, WITH A NARROW SPEED MAX IN ADVANCE OR WITH THE
FRONTAL BOUNDARY. HIGH CHANCES LOOK TO BE AROUND CAPE MENDO AND NEAR
OR JUST NORTH OF PT ST GEORGE DURING THE AFTERNOON AND EVENING
HOURS. A SURFACE LOW IS FORECAST TO SPIN UP OFFSHORE AND HEAD TOWARD
THE CENTRAL OREGON OFFSHORE WATERS FRI INTO SAT. A COUPLE OF TROUGHS
WILL PIN-WHEEL AROUND THIS LOW AND MAY EXTEND FAR ENOUGH SOUTH TO
GENERATE GALE GUSTS FOR THE NORTHERN WATERS FRIDAY NIGHT OR SAT.
MODELS HAVE BEEN FAIRLY CHAOTIC WITH HUGE VARIABILITY AND SPREAD
WITH THE MAGNITUDE AND TIMING OF STRONGEST WINDS WITH A SECONDARY
RAMP UP IN THE WINDS. PERSISTENT SOUTHERLY WINDS ASSOCIATED WITH
THIS LOW WILL LIKELY MAINTAIN STEEP AND ELEVATED SOUTHERLY WIND
WAVES THROUGH AT LEAST SAT. THIS LOW PRESSURE SYSTEM WILL ALSO
GENERATE ANOTHER LARGE SWELL THAT WILL SPREAD INTO NW CAL WATERS
LATE SAT INTO EARLY SUN. POTENTIAL FOR 20 FOOT W TO NW SWELL WILL
INCREASE THIS WEEKEND, PARTICULARLY SAT NIGHT INTO SUNDAY MORNING.
CONSIDERABLE MODEL VARIABILITY AND FORECAST UNCERTAINTY ARISES FOR
SUN AND MON WITH ADDITIONAL PERTURBATIONS AND FRONTAL WAVES POSSIBLY
BRINGING MORE IMPACTFUL WINDS AND SEAS.
BEACH HAZARDS
A NEW LONG PERIOD NW SWELL WILL ARRIVE ON THURSDAY
AND MIX WITH AN OLDER SHORTER PERIOD NW SWELL. THE THREAT FOR
SNEAKER WAVES AND ABOVE NORMAL SURF WILL INCREASE DURING THE
AFTERNOON AND EVENING HOURS AS THE SWELL BUILDS ABOVE 4 FEET AT 18
SECONDS. SHORTER PERIOD SWELL DIMINISHES THU NIGHT AND THE NEW SWELL
WILL ONCE AGAIN DOMINATE THE SPECTRUM. A MUCH LARGER WAVE EVENT IS
POSSIBLE THIS WEEKEND, 18-20 FOOT SWELL WITH BREAKER OVER 20 FT. THE
CLOSER PROXIMITY OF THE WAVE GENERATION REGION WILL PROBABLY KEEP
SWELL PERIODS AROUND 13-15 SECONDS. SWELL MAY GET A BOOST FROM WEST
AND SOUTHWEST WINDS ONCE WITHIN THE COASTAL WATERS OR JUST OUTSIDE.
WE POSTED A BEACH HAZARD STATEMENT FOR THE NEXT SWELL EVENT EXPECTED
FOR THU-FRI. WE MAY NEED A HIGH SURF ADVISORY FOR THE WEEKEND WAVE
EVENT. PERIODS ARE SHORTER AND STEEP WIND WAVES NEARSHORE WILL BE
FACTOR.
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.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
BEACH HAZARDS STATEMENT FROM THURSDAY AFTERNOON THROUGH
LATE THURSDAY NIGHT FOR CAZ101-103-104.
BEACH HAZARDS STATEMENT FROM THURSDAY AFTERNOON THROUGH
FRIDAY EVENING FOR CAZ109.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 5 PM PDT THIS AFTERNOON FOR
PZZ450-455.
SMALL CRAFT ADVISORY UNTIL 2 PM PDT THIS AFTERNOON 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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