978
FXUS66 KEKA 122137
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
237 PM PDT TUE AUG 12 2025
SYNOPSIS
HOT AND DRY WEATHER WILL CONTINUE TO SLOWLY EASE THROUGH
MIDWEEK WITH SHALLOW MARINE AIR ALONG SHORE. GUSTY NORTHWEST WIND
WILL ACCOMPANY BUILDING MARINE INFLUENCE LATE IN THE WEEK.
DISCUSSION
HIGH PRESSURE SITTING OVER THE AREA TODAY
HAS JUST STARTED TO DECAY, ALLOWING FOR THE HOTTEST INTERIOR VALLEYS
TO DROP BACK CLOSE TO 100. A SHALLOW BUT PERSISTENT MARINE LAYER HAS
BLANKETED THE COAST KEEPING CONDITIONS GENERALLY COOL IN THE UPPER
50S. HIGH PRESSURE WILL CONTINUE TO WEAKEN THROUGH THE END OF THE
WEEK AS A SHORTWAVE TROUGH GRADUALLY FORMS ALONG SHORE. TH SETUP
WILL HELP FURTHER EASE INTERIOR HIGHS BY ABOUT 10 DEGREES OVER THE
NEXT 2 DAYS. LIFTING WITH THIS SHORTWAVE WILL BE TOO WEAK TO
PROPERLY LIFT MARINE INFLUENCE MUCH INLAND BUT WILL BE STRONG ENOUGH
TO LIFT THE MARINE LAYER ALONG COAST, PERHAPS EVEN ENOUGH FOR SOME
VERY LIGHT DRIZZLE, ESPECIALLY ALONG THE MENDOCINO COAST OVER THE
NEXT COUPLE OF NIGHTS.
AROUND FRIDAY, A PROPER, DEEP WAVE TROUGH WILL SWEEP ACROSS THE
PACIFIC NORTHWEST AND HELP DEEPEN AND LIFT MARINE INFLUENCE INLAND.
HIGHS WILL BOTTOM OUT THIS WEEKEND IN THE LOW 90S FOR THE INTERIOR
ALONGSIDE WISPY MID AND HIGH LEVEL 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. A RELATIVELY TROUGHY PATTERN WILL MOST LIKELY PERSIST
THROUGH NEXT WEEK, MAINTAINING COOLER AND MORE MOIST CONDITIONS. SUCH
CONDITIONS MAY BRING A SLIGHT CHANCE OF THUNDERSTORMS EARLY NEXT
WEEK BUT THAT THREAT IS CURRENTLY VERY UNCERTAIN. /JHW
AVIATION
THE ONCE PERSISTENT RIDGE OF HIGH PRESSURE
OVER THE REGION IS WEAKENING, AND THE MARINE LAYER IS RESPONDING WITH
SOME SLIGHT DEEPENING. THE LOW LEVEL INVERSION IS STILL STRONG ON
TUESDAY, AND LIFR CIGS AND VIS WILL REMAIN POSSIBLE TODAY. VISIBLE
SATELLITE REVEALS A GOOD AMOUNT OF WEAKNESS AND SOME CLEARING
THROUGHOUT THE COASTAL MARINE LAYER. THIS WILL AMOUNT TO A SLIGHTLY
BETTER OPPORTUNITY FOR PERIODS OF CLEARING AND VFR AT THE COASTAL
TERMINALS, THOUGH THE WINDOW MAY BE SMALL WITH THE STRONG INVERSION.
A WEAK SHORTWAVE WILL PUSH IN FROM THE SW OVERNIGHT AND THROUGH
WEDNESDAY. SOUNDINGS SHOW A SLIGHT AMOUNT OF ADDITIONAL MARINE LAYER
DEEPENING. CHANCES FOR LIFR ARE HIGH AT THE COAST THROUGH THIS
PERIOD (70-90%). THERE IS SOME QUESTION ON THE DURATION OF FOG
TONIGHT, CURRENTLY ANTICIPATING AT LEAST TEMPO BOUTS OF FOG THROUGH
THE EARLY MORNING HOURS AS THE SHORTWAVE ENERGY MOVES THROUGH AND
THE MARINE LAYER DEEPENS SOME. THIS WILL ALSO HAVE A WEAKENING
EFFECT ON THE INVERSION WEDNESDAY, PERHAPS PROMOTING BETTER
CLEARING. JJW
MARINE
NORTHERLY WINDS REMAIN LIGHT TODAY OVER ALL 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 16
SECONDS TODAY. NORTHERLY WINDS WILL BEGIN TO RESTRENGTHEN WEDNESDAY
AND WILL BE THE STRONGEST THURSDAY AT 20-25KTS WITH ISOLATED 30KTS
AND GALE STRENGTH GUSTS AROUND CAPE MENDOCINO. SHORT PERIOD SEAS ARE
FORECAST TO BUILD UP TO 9 FEET OVER THE OUTER WATERS WEDNESDAY
EVENING THROUGH THURSDAY NIGHT. WINDS AND SEAS WILL EASE FRIDAY,
LIKELY REMAINING LOW THROUGH THE WEEKEND. JJW
FIRE WEATHER
PERSISTENT HOT AND DRY WEATHER HAS HELPED INCREASE
FIRE DANGER ALL ACROSS THE AREA WITH ERC FORECAST FOR NEAR RECORD
VALUES OVER THE NEXT COUPLE OF DAYS. THANKFULLY, CONDITIONS WILL
GENERALLY QUICKLY EASE OVER THE NEXT COUPLE OF DAYS WITH HIGHS
DROPPING BACK INTO THE 90S AND AND RH BACK AROUND 25 PERCENT. RH
RECOVERIES WILL ESPECIALLY IMPROVE WITH RECOVERIES GENERALLY BACK
ABOVE 70 PERCENT TONIGHT. THERE REMAINS A VERY LOW CHANCE OF
ISOLATED THUNDERSTORMS AS LOW PRESSURE BUILDS ALONG THE COAST (LESS
THAN 5%) TONIGHT INTO WEDNESDAY EVENING. ALL THAT SAID, CONDITIONS
WILL STILL BE GENERALLY WARM AND DRY AND FUELS WILL BE SLOW TO
RESPOND. 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 A VERY SLIGHT CHANCE OF THUNDERSTORMS EARLY NEXT WEEK.
/JHW
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
NONE.
NOTE: THE FULL FORECAST DISCUSSION IS NOW REGULARLY ISSUED BETWEEN
10 AM/PM AND 1 PM/AM. ADDITIONAL UPDATES WILL BE ISSUED AS NEEDED.
VISIT US AT HTTPS://WWW.WEATHER.GOV/EUREKA
FOLLOW US ON FACEBOOK AND TWITTER AT:
HTTPS://WWW.FACEBOOK.COM/NWSEUREKA
HTTPS://WWW.TWITTER.COM/NWSEUREKA
FOR FORECAST ZONE INFORMATION
SEE THE FORECAST ZONE MAP ONLINE:
HTTPS://WWW.WEATHER.GOV/IMAGES/EKA/ZONEMAP.PNG
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page