682
FXUS66 KEKA 140713
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
1213 AM PDT THU AUG 14 2025
SYNOPSIS
WARM WEATHER WILL CONTINUE TO RAPIDLY DECLINE AS GUSTY
NORTHWEST WINDS HELP PULL IN COOLER MARINE AIR THURSDAY AND FRIDAY.
COOL WEATHER WILL CONTINUE THIS WEEKEND WITH MIDLEVEL CLOUDS AND
POSSIBLY EVEN WETTING RAIN FOR THE NORTHERN HALF OF THE AREA.
DISCUSSION
TEMPERATURES CONTINUE TO COOL AS AN EASTERN PACIFIC
CUTOFF LOW STRENGTHENS AND ORGANIZES. THE UPPER WAVE IS FORMING
AN OMEGA BLOCKING PATTERN ON SYNOPTIC SCALE WITH A DEEPER LOW OVER
EASTERN CANADA. A CONSIDERABLE SLUG OF MOISTURE WILL TAKE AIM AT
THE PACNW JUST BEFORE THE WEEKEND, LIKELY TO ARRIVE IN THE COASTAL
NORTHERN AREAS OF OUR CWA BY FRIDAY WITH HEAVIER PRECIPITATION
HITTING THE OREGON COAST.
THIS PROPER, DEEP WAVE TROUGH WILL SWEEP ACROSS THE PACNW AND
HELP DEEPEN AND LIFT MARINE INFLUENCE INLAND. HIGHS WILL BOTTOM
OUT THIS WEEKEND IN THE LOW 90S FOR THE INTERIOR ALONGSIDE
SIGNIFICANT HIGH AND MIDLEVEL CLOUDS. GUSTY NORTHWEST WINDS WILL
ACCOMPANY A DIFFUSE SURFACE COLD FRONT AS THE COOLER AIR SWEEPS
INLAND AS SOON AS THURSDAY AFTERNOON BUT ESPECIALLY ON FRIDAY.
GUSTS ON EXPOSED RIDGES AND IN CHANNELED VALLEYS COULD EASILY
REACH 30 MPH OR MORE EACH AFTERNOON, ESPECIALLY IN LAKE AND
MENDOCINO COUNTIES WHERE THERE IS EVEN A 10 TO 20% CHANCE OF
ISOLATED GUSTS OVER 40 MPH ALONG HIGH TERRAIN.
THE HIGHEST UNCERTAINTY IN THE FORECAST HAS TO DO WITH THE
POTENTIAL FOR PRECIPITATION THIS WEEKEND. THERE IS HIGH CONFIDENCE
THAT A PLUME OF MOISTURE REMINISCENT OF AN ATMOSPHERIC RIVER WILL
ACCOMPANY THE DEEP TROUGH (PRECIPITABLE WATER 1 TO 1.5 INCHES), BUT
THERE IS MUCH LESS CERTAINTY REGARDING EITHER INSTABILITY OF LIFT
SUFFICIENT TO PRODUCE RAIN. CURRENTLY, THERE IS A WIDE RANGE IN THE
FORECAST. THE GREATEST CHANCE OF RAIN WOULD BE ALONG THE COAST NORTH
OF HUMBOLDT BAY AND DUE TO SHOWERS OVER HIGH TERRAIN IN TRINITY
COUNTY. ABOUT 70% OF MODELS SHOW AT LEAST A TRACE OF RAIN IN
CRESCENT CITY ON SATURDAY WITH NEARLY 40% SHOWING EVEN WETTING RAIN.
THOSE CHANCES FALL RAPIDLY FURTHER SOUTH IN EUREKA. RAIN IN THE
INTERIOR WOULD LIKELY FALL IN SHOWERS OVER HIGH TERRAIN, SOME OF
WHICH COULD BECOME ISOLATED THUNDERSTORMS (15% OR LESS).
THUNDERSTORMS WOULD BE FAIRLY WET WITH ABOUT A 30% CHANCE WETTING
RAIN ACROSS INTERIOR TRINITY COUNTY. THERE IS LITTLE TO NO POTENTIAL
FOR WETTING RAIN FOR THE SOUTHERN HALF OF THE AREA. /JHW
AVIATION...(06Z TAFS)
THE MARINE LAYER WILL FURTHER DEEPEN INTO
EARLY THURSDAY, AND WILL ALLOW FOR A FURTHER PUSH EASTWARD OF
STRATUS INTO EARLY THURSDAY, WITH LIFR CONDITIONS LIKELY EVEN TO
KNEELAND AIRPORT.
LIFR CEILINGS OF 200 TO 400FT AGL HAVE REDEVELOPED AND WILL CONTINUE
THROUGH THURSDAY MORNING FOR ACV AND CEC AND SOUTHWARD THROUGH
SHELTER COVE. SOUNDINGS SHOW A SIMILAR INVERSION HEIGHT AROUND ACV
BUT A SLIGHTLY SHALLOWER LEVEL FARTHER NORTH AT CEC. DURATION OF FOG
LOOKS LIMITED TO TEMPO CRITERIA, WITH HIGHEST CHANCES FROM 11-15Z
THURSDAY (30%). CHANCES ARE SLIGHTLY HIGHER AT CEC THROUGH THIS
PERIOD (40%).
MODELS HINT AT STRATUS MAKING A PUSH UP THE RUSSIAN RIVER VALLEY
INTO EARLY THURSDAY, BUT CONFIDENCE REMAINS BELOW THRESHOLDS FOR TAF
INCLUSION. SOUTHERLY WINDS ARE EXPECTED OVERNIGHT, THOUGH.
THERE IS HIGHER CONFIDENCE FOR THE INVERSION TO GREATLY WEAKEN
THURSDAY AND CONTRIBUTE TO BETTER CLEARING THROUGHOUT THE DAY.
CLEARING IS FORECAST TO QUICKLY OCCUR SOUTH OF THE CAPE AROUND
SHELTER COVE EARLY THURSDAY MORNING BY 9Z, BUT MAY NOT FULLY OCCUR
ELSEWHERE ALONG THE COAST BEYOND 18Z THURSDAY.
WINDS REMAIN RELATIVELY LIGHT THROUGH THIS PERIOD. A SOUTHERLY WIND
REVERSAL WILL BRING SOME SOUTHERLY GUSTS ALONG THE FAR NORTH COAST
TO CEC INTO THURSDAY MORNING. NORTHERLIES WILL INCREASE ACROSS THE
REGION ON THURSDAY, BECOMING BREEZY IN THE AFTERNOON.
MARINE
SMALL CRAFT NORTHERLY WINDS WILL CONTINUE OVER THE
OUTER MARINE ZONES. SEAS ARE 5-7 FEET FROM LONG PERIOD SOUTHERLY
SWELLS AND A SHORT PERIOD NORTHWEST SWELL. THE SOUTH SWELL PERIOD
WILL MOSTLY BE AT 15 SECONDS THROUGH THURSDAY. NORTHERLY WINDS WILL
CONTINUE TO STRENGTHEN THURSDAY AT 20-25 KTS WITH ISOLATED 30 KTS
AND GALE STRENGTH GUSTS AROUND CAPE MENDOCINO. SHORT PERIOD SEAS ARE
FORECAST TO BUILD UP TO 9 FEET OVER THE OUTER WATERS THROUGH
THURSDAY NIGHT. WINDS AND SEAS WILL EASE FRIDAY, LIKELY REMAINING
LOW THROUGH THE WEEKEND. JJW
FIRE WEATHER
HOT AND DRY WEATHER RAPIDLY PULLS BACK, THOUGH
FIRE DANGER INDICES REMAIN VERY ELEVATED AS FUELS LAG. MODERATELY
ELEVATED CONDITIONS WILL PERSIST OVER THE NEXT COUPLE DAYS WITH
HIGHS DROPPING BACK INTO THE 90S AND AND RH BACK AROUND 25
PERCENT. RH RECOVERIES, HOWEVER, WILL ESPECIALLY IMPROVE WITH
RECOVERIES GENERALLY OVER 0 PERCENT, ESPECIALLY AT LOWER
ELEVATIONS. STRONG NORTHWEST WINDS WILL BUILD IN DURING THE
AFTERNOONS THURSDAY AND FRIDAY AHEAD OF A ONSHORE MARINE PUSH.
GUSTS IN EXCESS OF 30 MPH ARE MOST LIKELY ON RIDGES EXPOSED TO THE
NORTHWEST AND IN CHANNELED VALLEYS, ESPECIALLY ALONG THE RUSSIAN
RIVER AND AROUND CLEAR LAKE. COOLER AND MORE MOIST CONDITIONS WILL
PERSIST INTO THIS WEEKEND WITH POTENTIAL FOR LIGHT WETTING RAIN
ALONG THE NORTH COAST (40% CHANCE) AND WET SHOWERS AND
THUNDERSTORMS IN TRINITY COUNTY (30% CHANCE). /JHW
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY FROM 11 AM THURSDAY TO 8 PM PDT FRIDAY
FOR PZZ455.
SMALL CRAFT ADVISORY UNTIL 9 PM PDT THURSDAY FOR PZZ470.
SMALL CRAFT ADVISORY UNTIL 8 PM PDT FRIDAY 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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