013
FXUS66 KEKA 152126
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
226 PM PDT FRI AUG 15 2025
SYNOPSIS
A WEAK EARLY SEASON COLD FRONT WILL BRING SLIGHT, LIGHT
RAIN POTENTIAL TO THE COAST EARLY SATURDAY WITH SHOWERS POSSIBLE
INLAND. ANY MEASURABLE RAIN POTENTIAL WILL REMAIN NORTH OF CAPE
MENDOCINO. WARMER AND DRIER WEATHER GRADUALLY RETURNS NEXT WEEK.
DISCUSSION
THE EFFECTS OF AN APPROACHING UPPER LEVEL
TROUGH HAVE BEEN ON FULL DISPLAY TODAY. GUSTY NORTHWEST WINDS HAS
QUICKLY BUILD IN THIS AFTERNOON, ESPECIALLY OR THE SOUTHERN HALF OF
THE AREA WITH GUSTS OF 30 TO 40 MPH IN EXPOSED AREAS. CONDITIONS
HAVE ALSO CONTINUED TO COOL AND MOISTEN WITH MARINE AIR ADVECTING
INLAND. HIGHS HAVE GENERALLY FALLEN BELOW 90. MID AND UPPER LEVEL
CLOUDS HAVE JUST STARTED TO ARRIVE ALONG SHORE: THE FIRST SIGNS OF
MOISTURE APPROACHING ALONG THE TROUGH.
A PLUME OF MOISTURE WILL MOVE ONSHORE EARLY SATURDAY WITH IMPRESSIVE
PWATS FOR AUGUST BETWEEN 1 AND 1.5 INCHES. ACTUAL INSTABILITY AND
SYNOPTIC LIFT WILL BE MARGINAL AT BEST, BUT NORTHWEST WIND AT THE
SURFACE SHOULD HELP PRODUCE AT LEAST SOME LIFT TO GENERATE LIGHT
PRECIPITATION ALONG THE COAST EARLY SATURDAY MORNING. THERE IS AN
80% CHANCE FOR AT LEAST TRACE AMOUNTS OF RAIN ALONG THE DEL NORTE
COAST AND A 60% CHANCE OF WETTING RAIN. SIMILARLY FOR HUMBOLDT BAY,
THERE IS A 65% CHANCE OF AT LEAST TRACE AMOUNTS OF RAIN AND A 30%
CHANCE OF WETTING RAIN. DESPITE THE RAIN, INCREASED INSTABILITY WILL
DISRUPT THE MARINE LAYER, LIKELY HELPING IN BETTER COASTAL CLEARING
THIS WEEKEND, AT LEAST WHEN ITS NOT RAINING. CHANCES OF WETTING RAIN
QUICKLY DIMISH INLAND AND FURTHER SOUTH WITH NEAR 0% CHANCE OF ANY
WETTING RAIN SOUTH OF THE KING RANGE.
RAIN WILL FOCUS ON THE COAST IN THE MORNING WITH MOISTURE PUSHING
INLAND BY THE AFTERNOON. ANY RAIN FALLING OVER THE INTERIOR WILL
MOST LIKELY FALL AS SCATTERED AND INCONSISTENT SHOWERS. THERE IS A
GENERAL 40% CHANCE OF ANY GIVEN POINT IN TRINITY COUNTY SEEING
WETTING RAIN, THOUGH ACTUAL COVERAGE WOULD BE VERY SPLOTCHY AT BEST.
COLDER AIR MOVING IN BEHIND THE MOISTURE WILL DEEPEN INSTABILITY,
BRINING A VERY SLIGHT CHANCE OF THUNDERSTORMS (<15%) SATURDAY
EVENING AND AGAIN SUNDAY AFTERNOON.
THERE IS HIGH MODEL CONFIDENCE THAT WEAK HIGH PRESSURE AND HENCE
WARMER AND DRIER WEATHER WILL GRADUALLY REASSERT ITSELF THROUGH NEXT
WEEK. THOUGH THERE IS A RANGE OF UNCERTAINTY BY THE END OF NEXT
WEEK, THERE IS LITTLE CHANCE OF EXTREME HEAT (20% OR LESS) RETURNING
WITH HIGHS MOST LIKELY STAYING JUST AT OR BELOW 100 FOR INTERIOR
LOCATIONS. /JHW
AVIATION
AFTER A PERIOD OF SUNSHINE ALONG THE NORTH
COAST, STRATUS PUSH BACK INLAND THIS AFTERNOON. VARIABLE CONDITIONS
AT CEC, ACV AND AROUND HUMBOLDT BAY, WITH MIXING CLOUDS. MEANWHILE,
VFR CONDITIONS ACROSS MUCH OF THE MENDOCINO COAST AND INTERIOR,
INCLUDING UKI. SURFACE WINDS FROM WNW AT 5-10 KTS FOR ACV AND CEC,
WHILE BREEZY WINDS FROM 10-15 KTS AND HIGHER GUSTS HAVE DEVELOPED
AGAIN ACROSS THE INTERIOR AND UKI THIS AFTERNOON.
THE MARINE IS EXPECTED TO DEEPEN TONIGHT AS AN UPPER LEVEL TROUGH
DIG SOUTHWARD. HIGH AND MID LEVEL CLOUDS WILL CONTINUE TO SPREAD
ACROSS THE NORTHERN PORTION OF THE FORECAST AREA TONIGHT AHEAD OF AN
ASSOCIATED WEAK COLD FRONT, WITH LIGHT RAIN OR SPRINKLES ARRIVING
FIRST AT CEC AROUND 11Z AND THEN SPREADING SOUTH TO ARRIVE AT ACV
AROUND 13Z. THE COLD FRONT WILL SLOW MOVE SOUTH AND EAST THROUGHOUT
THE DAY ON SATURDAY, WITH INCREASING CLOUD COVER ACROSS THE
INTERIOR. ISOLATED SHRA WILL MOST LIKELY ACROSS THE INTERIOR FARTHER
NORTH OF LAKE COUNTY SATURDAY AFTERNOON. /ZVS
MARINE
MODERATE TO STRONG NORTHERLY WINDS CONTINUE DOWNWIND OF
CAPE MENDOCINO, WHILE LIGHTER WINDS ACROSS THE NORTHERN WATERS.
NORTHERLY WINDS ARE EXPECTED TO DIMINISH INTO SATURDAY. SHORT-PERIOD
SEAS WILL CONTINUE TO SUBSIDE THROUGH TONIGHT AS WINDS DIMINISH.
FOR THE WEEKEND, NORTHERLIES WILL BE GENERALLY LIGHT TO MODERATE
BREEZES ACROSS THE COASTAL WATERS. ALTHOUGH, EXPECT FRESH BREEZES
LEEWARD OF CAPE MENDOCINO EACH AFTERNOON. A NW SWELL WILL BUILD IN
SATURDAY AFTERNOON, AND PEAKING TO AROUND 5 TO 6 FEET AT AROUND 10
SECONDS SATURDAY NIGHT/EARLY SUNDAY.
RELATIVELY CALM CONDITIONS WITH LIGHT TO GENTLE BREEZES AND LOW SEAS
WILL CONTINUE EARLY TO MID NEXT WEEK, BEFORE NORTHERLY WINDS
INCREASE AGAIN BY MID WEEK. /ZVS
FIRE WEATHER
NORTHWEST WINDS GUSTING OVER 30 MPH IN EXPOSED AREAS
THIS AFTERNOON WILL CONTINUE TO ENHANCE FIRE DANGER, PARTICULARLY
AROUND THE RUSSIAN RIVER VALLEY AND CLEAR LAKE WHERE WINDS RE
HIGHEST. THAT SAID, GUSTY WIND IS ALSO PULLING IN COOLER AND MORE
MOIST MARINE AIR. RAIN CHANCE AND VERY HIGH RH RECOVERIES OVER THE
WEEKEND WILL GREATLY SUBDUE FIRE WEATHER CONCERNS, THOUGH SLIGHT
CHANCES FOR THUNDERSTORMS OVER TRINITY COUNTY SATURDAY EVENING AND
AGAIN SUNDAY AFTERNOON (15% CHANCE) WILL GENERATE SOME POSSIBLE
IGNITIONS. OTHERWISE, WARM AND DRY WEATHER WILL GRADUALLY RETURN
THROUGH NEXT WEEK. /JHW
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR
PZZ455-475.
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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