366
FXUS66 KEKA 042037
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
137 PM PDT THU SEP 4 2025
SYNOPSIS
ANOTHER HOT AND DRY DAY EXPECTED TODAY FOR THE INTERIOR.
THERE IS A SLIGHT CHANCE FOR DRY THUNDERSTORMS IN DEL NORTE COUNTY
THIS AFTERNOON AND EVENING. STRATUS LIKELY TO REMAIN PERSISTENT ON
THE COAST. SUNDAY NIGHT INTO MONDAY THERE IS A CHANCE FOR A WETTING
RAIN IN THE NORTHERN PORTION OF THE AREA AND INTERIOR HIGHS DOWN
INTO THE 70S.
DISCUSSION
THE RIDGE REMAINS OVER THE WESTERN PORTION OF THE
U.S. AND AN UPPER LEVEL LOW IS STARTING TO APPROACH THE AREA. AS
IT DOES IT STARTS TO ELONGATE AND A SHORTWAVE TROUGH FORMS SOUTH
OF IT AND STARTS TO ROTATE TOWARDS THE COAST FRIDAY EVENING.
ANOTHER TROUGH FOLLOWS THIS AND ROTATES AROUND ON SATURDAY
EVENING. FINALLY ON MONDAY THE UPPER LEVEL LOW STARTS TO BECOME
AN OPEN WAVE AND MOVE ONSHORE.
TODAY THROUGH SUNDAY THESE SHORTWAVES ROTATING AROUND THE LOW ARE
EXPECTED TO ENHANCE THE COASTAL DRIZZLE. TONIGHT INTO FRIDAY
MORNING THE NBM IS STILL SHOWING A 20 TO 30 PERCENT CHANCE OF OVER
A TENTH OF AN INCH. THIS IS GENERALLY AT THE COAST AND THE
PROBABILITIES DIMINISH QUICKLY FARTHER INLAND. THESE PROBABILITIES
DROP TO AROUND 10 TO 20 PERCENT ALONG THE COAST FOR THE WEEKEND.
AS THE AIR ALOFT GETS COOLER AND THE INVERSION STARTS TO WEAK,
THE CLOUDS AT THE COAST MAY BREAK UP IN THE AFTERNOON, BUT
OTHERWISE CLEARING MAY BE LIMITED. THE HIGH TEMPERATURES WILL BE
NEAR 100 AGAIN TODAY IN THE INLAND AREAS, ALTHOUGH SOME OF THE
NEAR COASTAL AREAS MAY BE COOLER AS THE MARINE AIR MAKES ITS WAY
UP THE RIVER VALLEYS. FAIRLY SIGNIFICANT COOLING IS EXPECTED
FRIDAY AND INTO THE WEEKEND. HIGHS FRIDAY ARE EXPECTED TO BE IN
THE UPPER 80S TO LOW WITH A FEW DEGREES OF COOLING BOTH SATURDAY
AND SUNDAY. AREAS CLOSER TO THE COAST MAY COOL EVEN MORE.
SUNDAY AFTERNOON AND EVENING THE UPPER LEVEL LOW STARTS TO GET
CLOSE TO THE AREA AND MAY START TO BRING SOME SHOWERS OR POSSIBLY
EVEN A THUNDERSTORM TO THE AREA. THIS IS GENERALLY NOT A PATTERN
CONDUCIVE TO THUNDERSTORMS.
MONDAY THE UPPER LEVEL TROUGH MOVES ONSHORE AND TUESDAY THIS GETS
REINFORCED BY A LARGE TROUGH THAT SETTLES OVER THE WEST COAST AND
REMAINS IN PLACE ON WEDNESDAY AND THURSDAY. OVERALL THE ENSEMBLES
ARE IN PRETTY GOOD AGREEMENT ON THE TROUGH OVER THE WEST COAST.
THE CHALLENGE LIES IN WHERE EXACTLY THIS LOW GOES AND THIS WILL
IMPACT THE DETAILS OF HOW MUCH RAIN OCCURS AND WHERE IT WILL BE.
HERE ARE SOME PROBABILITIES OF RAINFALL TOTALS FROM 5AM SUNDAY
THROUGH 5AM WEDNESDAY. THERE IS A 70 TO 80 PERCENT CHANCE OF
EXCEEDING AN INCH IN DEL NORTE COUNTY, A 50 TO 60 PERCENT CHANCE
ON THE HUMBOLDT COAST, AND AROUND 40 TO 50 PERCENT CHANCE IN THE
MOUNTAINS OF INTERIOR HUMBOLDT AND TRINITY COUNTIES. THE
PROBABILITIES DROP OFF QUICKLY IN MENDOCINO AND LAKE COUNTIES FOR
AN INCH, HOWEVER FOR A TENTH OF AN INCH THERE IS A 40 TO 70
PERCENT CHANCE IN MENDOCINO AND LAKE COUNTIES WITH THE HIGHEST IN
THE NORTHERN MOUNTAINS. THE NBM IS HIGHLIGHTING THUNDERSTORMS WITH
THIS SYSTEM AS THE TROUGH MOVES OVERHEAD. CONFIDENCE THIS WILL
ALSO KEEP TEMPERATURES COOLER AND HIGHS WILL LIKELY BE IN THE 60S
TO LOW 70S. MKK
AVIATION...04/18Z TAFS
MAINLY LIFR CONDITIONS ALONG THE COASTAL
TERMINALS. LOW CLOUDS ARE EXPECTED TO LIFT TO IFR THIS AFTERNOON,
AND PERHAPS TO MVFR LATE IN THE AFTERNOON. A DEEPER MARINE LAYER IS
EXPECTED TO DEVELOP TONIGHT AS AN UPPER LEVEL TROUGH APPROACHES FROM
THE WEST. EXPECT VARIABLE CONDITIONS BETWEEN LIFR/ IFR/MVFR
CONDITIONS ATE THE COASTAL TERMINALS TONIGHT THROUGH FRIDAY MORNING.
PATCHY DRIZZLE IS EXPECTED TO OCCUR ALONG THE COAST WITH THIS
SATURATED LAYER. SURFACE WINDS FROM WSW AROUND 5 KTS, BECOMING VERY
LIGHT S WINDS AND VARIABLE AFTER 05/03Z.
FOR INLAND AREAS: VFR CONDITIONS WITH HIGH LEVEL CLOUDS STREAMING
ACROSS THE AREA, INCLUDING IN KUKI. LATE TONIGHT INTO FRIDAY
MORNING, HIGH-RES MODEL GUIDANCE SUGGEST SOME LOW CLOUDS DEVELOPING
IN THE VICINITY OF UKI WITH A DEEPER MARINE LAYER. THERE IS A 20%
CHANCE FOR CEILING HEIGHT AT 1000 FEET OR LOWER BY EARLY FRIDAY
MORNING. VERY LIGHT AND VARIABLE WINDS, BECOMING S AT AROUND 10 KTS
AFTER 19Z, SHIFTING TO NNE AFTER 05/00Z, THEN VERY LIGHT AND
VARIABLE WINDS THROUGH FRIDAY MORNING. /ZVS
MARINE
GENTLE TO MODERATE BREEZES ACROSS THE OUTER WATERS, WHILE
LIGHT TO GENTLE OVER THE INNER WATERS. LOCALIZE GUSTY WINDS UP TO 25
KTS ARE EXPECTED TO DEVELOP DOWNWIND OF CAPE MENDOCINO LATE THIS
AFTERNOON THROUGH TONIGHT. STEEP SHORT PERIOD SEAS WILL CONTINUE TO
GENERATE HAZARDOUS CONDITIONS FOR SMALL CRAFT THROUGH THIS
AFTERNOON.
CONDITIONS ARE EXPECTED TO CONTINUE IMPROVING FRIDAY AND INTO THE
WEEKEND AS AN UPPER LEVEL TROUGH APPROACHES FROM THE WEST AND THE
SURFACE PRESSURE GRADIENT RELAXES. WINDS SHIFT TO SOUTHERLY AND
SLIGHTLY INCREASE AHEAD OF AN ASSOCIATED FRONTAL SYSTEM THIS
WEEKEND. SMALL, MID- PERIOD NW AND SW SWELLS WILL PERSIST THROUGH
THE WEEKEND. OVERALL RELATIVELY CALM CONDITIONS ARE FORECASTED FOR
THIS WEEKEND THROUGH EARLY NEXT WEEK. /ZVS
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 3 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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