188
FXUS66 KEKA 130723
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
1223 AM PDT WED AUG 13 2025
SYNOPSIS
HOT AND DRY WEATHER WILL CONTINUE TO SLOWLY EASE THROUGH
MIDWEEK WITH SHALLOW MARINE AIR ALONG THE SHORE. GUSTY NORTHWEST
WIND WILL ACCOMPANY BUILDING MARINE INFLUENCE LATE IN THE WEEK.
DISCUSSION
HIGH PRESSURE WILL SUCCUMB TO A TROUGH LOBE,
ELONGATING FROM THE UPPER WAVE PATTERN OVERNIGHT INTO WEDNESDAY
AND LASTING A FEW DAYS AS TEMPERATURES EASE AND THE POSSIBILITY OF
DRIZZLE OR LIGHT ACCUMULATION ARISE FOR ADJACENT COASTAL AREAS OF
THE CWA. NO DEFINITE SIGNS OF UPLIFTING AIR/INSTABILITY WITH THIS
SHORTWAVE AS TROUGH DYNAMICS LACK VORTICITY AND SHEAR. IT IS MORE
LIKELY THAT THERE WILL BE STRATIFORM PRECIPITATION AND MOSTLY
OFFSHORE WITH SOME NEAR SHORE ACCUMULATION. HIGH RESOLUTION MODEL
SOUNDINGS SHOW SATURATED BOUNDARY LAYER WITH A WARM AIR MASS
ALOFT, INDICATIVE OF A DRIZZLE EVENT.
AROUND FRIDAY, A PROPER, DEEP WAVE TROUGH WILL SWEEP ACROSS THE
PACIFIC NORTHWEST AND HELP DEEPEN AND LIFT MARINE INFLUENCED AIR
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 /EYS
AVIATION
(06Z TAFS)
OVERNIGHT INTO WEDNESDAY: A WEAK SHORTWAVE APPROACHES FROM THE
SOUTHWEST, FURTHER DEEPENING THE MARINE LAYER. THIS CREATES A HIGH
PROBABILITY (70-100%) OF LIFR (LOW INSTRUMENT FLIGHT RULES)
CONDITIONS PERSISTING AT THE COAST. WHILE THE DURATION OF FOG IS
UNCERTAIN, TEMPORARY BOUTS ARE EXPECTED THROUGH EARLY MORNING AS THE
SHORTWAVE TROUGH PASSES AND THE MARINE LAYER DEEPENS. THIS SHOULD
ALSO WEAKEN THE INVERSION, POTENTIALLY LEADING TO BETTER CLEARING BY
WEDNESDAY.
CRESCENT CITY (KCEC):
- SKY COVER: MEAN SKY COVER REMAINS NEAR 100 PERCENT UNTIL 16Z,
THEN SLOWLY DECREASES TO 50 PERCENT BY 01Z BEFORE INCREASING TO 80%
BY 06Z WED EVENING.
- CEILING LEVEL: MEAN CEILING LEVEL REMAINS BETWEEN 100 AND 300
FEET FOR THE ENTIRE FORECAST. THERE'S UP TO 80% CHANCE OF CEILINGS
BELOW 500 FEET, PEAKING NEAR 13Z WEDNESDAY.
- WINDS: NEAR CALM UNTIL 17Z WEDNESDAY, THEN GRADUALLY
INCREASING AND PEAKING AROUND 00Z THURSDAY WITH MEAN SUSTAINED
VALUES OF 8 KTS AND GUSTS TO 12 KTS FROM AROUND 270 DEGREES.
- VISIBILITY: DETERMINISTIC VISIBILITY DOWN TO 1/4SM UNTIL IT
IMPROVES AROUND 15Z WEDNESDAY, PEAKING AT 4SM BY 21Z, THEN WORSENING
AFTERWARD. THE GREATEST PROBABILITY (AROUND 50%) OF VISIBILITY LESS
THAN ONE MILE IS NEAR 12-13Z, INDICATING LOWER CONFIDENCE IN
VISIBILITY COMPARED TO CEILING FORECASTS.
ARCATA (KACV):
- SKY COVER: MEAN SKY COVER REMAINS 80-100% UNTIL 18Z WEDNESDAY,
DECREASING TO ABOUT 50% BY 00Z THURSDAY BEFORE INCREASING AGAIN
WEDNESDAY EVENING.
- CEILINGS: DETERMINISTIC CEILINGS REMAIN BETWEEN 100 AND 500
FEET FOR THE ENTIRE FORECAST, PEAKING BETWEEN 20Z AND 23Z WEDNESDAY.
- WINDS: MEAN SUSTAINED WIND SPEEDS ARE FORECAST TO REMAIN 6 KTS
OR LESS THROUGHOUT THE FORECAST PERIOD, PEAKING AT 6 KTS WITH GUSTS
TO 7 KTS AROUND 23Z WEDNESDAY.
- VISIBILITY: DETERMINISTIC FORECASTS SHOW 1/4 SM VISIBILITY
UNTIL 15Z WEDNESDAY WITH SOME IMPROVEMENT PEAKING AT 2.5 SM BETWEEN
19Z AND 23Z WEDNESDAY. THE CHANCE OF VISIBILITY BELOW 1SM PEAKS AT
40% NEAR 13Z, REFLECTING LOWER CONFIDENCE IN LOW VISIBILITY VALUES
COMPARED TO HIGHER CONFIDENCE IN LOWER CEILINGS.
UKIAH (UKI):
- SKY COVER: MEAN SKY COVER REMAINS 20% OR LOWER FOR THE ENTIRE
FORECAST PERIOD.
- CEILINGS: MEAN CEILINGS DO NOT DROP BELOW 20K FEET. DESPITE
DETERMINISTIC CEILINGS, THERE'S A 40% CHANCE OF CEILINGS BELOW 2K
FEET.
- WINDS: MEAN WINDS REMAIN LIGHT, WITH AN INCREASE IN THE
AFTERNOON, PEAKING AT 6KTS WITH GUSTS TO 14KTS FROM AROUND 290
DEGREES AROUND 23Z.
- VISIBILITY: THE CHANCE OF VISIBILITY LESS THAN 5SM REMAINS
BELOW 20-% FOR THE ENTIRE FORECAST PERIOD./MH
MARINE
WINDS ARE FORECAST TO STRENGTHEN FROM WEDNESDAY, PEAKING ON
THURSDAY WITH SUSTAINED SPEEDS OF 20-25 KTS AND ISOLATED GUSTS UP TO
30 KTS. GALE-FORCE GUST POTENTIAL EXISTS AROUND CAPE MENDOCINO.
SHORT-PERIOD SEAS ARE EXPECTED TO BUILD UP TO 9 FEET OVER THE OUTER
WATERS FROM WEDNESDAY EVENING THROUGH THURSDAY NIGHT. WINDS AND SEAS
WILL DIMINISH ON FRIDAY AND ARE LIKELY TO REMAIN LOW THROUGH THE
WEEKEND. /MH
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.
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