868
FXUS66 KEKA 082127
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
227 PM PDT WED JUL 8 2026
KEY MESSAGES
* PERSISTENT STRATUS: SEASONABLY COOL CONDITIONS ALONG THE IMMEDIATE
COAST WILL ALTERNATE WITH TYPICAL NIGHT AND MORNING LOW CLOUDS AND
FOG.
* BUILDING INTERIOR HEAT: A ROBUST RIDGE OF HIGH PRESSURE WILL
MAXIMIZE TEMPERATURE ANOMALIES ACROSS ALL INLAND VALLEYS,
INCLUDING LAKE, TRINITY, AND INTERIOR MENDOCINO COUNTIES, STARTING
LATE THIS WEEK.
SYNOPSIS
DIURNAL, SHALLOW COASTAL STRATUS IS ANTICIPATED FOR
COASTAL AND NEAR COASTAL AREAS WITH BETTER CHANCES FOR SCATTERING
OR CLEARING EACH AFTERNOON THROUGH THE END OF THE WEEK. INLAND
AREAS WILL REMAIN DRY AND HOT UNDER A BUILDING UPPER-LEVEL RIDGE.
DISCUSSION
THE FRINGES OF AN UPPER LEVEL TROUGH CENTERED OVER
BRITISH COLUMBIA AND AN UPPER LEVEL RIDGE OVER THE SOUTHWEST US
ARE INTERACTING WITH EACH OTHER OVER NORTHWEST CALIFORNIA. LAST
NIGHT AND THIS MORNING, THE UPPER LEVEL LOW BROUGHT MORE ZONAL
FLOW TO THE REGION WHICH AIDED IN DEEPENING COASTAL STRATUS AND
THEN LED TO CLEARING/SCATTERING STRATUS THIS AFTERNOON FOR MOST
COASTAL AREAS DUE TO ATMOSPHERIC MIXING. INLAND AREAS WILL
EXPERIENCE HEATING AS THE UPPER RIDGE STRENGTHENS AND MOVES
WESTWARD LATE THIS WEEK AND INTO THE WEEKEND. HIGH
TEMPERATURES IN THE MID TO UPPER 90S WILL BECOME WIDESPREAD
ACROSS THE INTERIOR VALLEYS OF TRINITY, MENDOCINO, AND LAKE
COUNTIES BY THURSDAY. SUBSIDENCE WILL COMPRESS THE MARINE LAYER,
KEEPING IT SHALLOW AND CONFINED TO THE COAST AND IMMEDIATE
VALLEYS.
LATE THIS WEEKEND AND INTO NEXT WEEK, THE PLACEMENT OF THE UPPER
RIDGE OVER THE SOUTHWEST WILL DETERMINE THE PATH OF MONSOONAL
MOISTURE OVER THE WESTERN US. NEXT WEEK HAS THE POTENTIAL TO HEAT
UP AND DRY OUT MORE THAN THE END OF THIS WEEK, AS WELL. THE
MONSOONAL MOISTURE COULD CAUSE INSTABILITY IN THE ATMOSPHERE,
MAINLY OVER NORTHEASTERN TRINITY COUNTY EARLY NEXT WEEK. AS OF
NOW, CHANCES FOR ISOLATED THUNDERSTORMS LOOK LOW, BUT THIS PATTERN
WILL BE MONITORED FOR ANY POTENTIAL IMPACTS TO NORTHWEST
CALIFORNIA. /JLW
AVIATION
CHANCES FOR LONGER PERIODS OF CLEARED OR SCATTERED
LOW CLOUDS ARE EXPECTED TO CONTINUE THIS AFTERNOON AND EVENING FOR
COASTAL TERMINALS. AS HIGH PRESSURE BECOMES MORE DOMINANT IN THE
REGION LATE THIS WEEK, COASTAL STRATUS IS EXPECTED TO BE LESS
WIDESPREAD AND MORE SHALLOW. IFR/LIFR CONDITIONS ARE EXPECTED TO
REDEVELOP FOR TERMINALS IN THE HUMBOLDT BAY AREA AND NEARSHORE
AREAS OF THE EEL RIVER VALLEY. ALONG THE DEL NORTE COAST, COASTAL
STRATUS DEVELOPMENT COULD BE STAVED OFF AS NORTHERLY WINDS
INCREASE CLOSER TO SHORE. VFR CONDITIONS ARE FORECAST FOR INLAND
TERMINALS THROUGHOUT THE TAF PERIOD. /JLW
MARINE
THE PRESSURE GRADIENT BETWEEN THE OFFSHORE LOWER LEVEL HIGH
AND THE INLAND THERMAL LOW IS TIGHTENING ACROSS THE WATERS. WINDS
SOUTH OF CAPE MENDOCINO ARE SUSTAINED AT 20 TO 25 KNOTS,
PRODUCING STEEP, WIND-DRIVEN SEAS IN THE SOUTHERN MARINE ZONES. A
GALE WATCH HAS BEEN HOISTED FOR THE SOUTHERN OUTER WATERS FOR
THURSDAY AS WIDESPREAD FREQUENT GUSTS OVER 34 KNOTS SEEMS TO BE
INCREASINGLY LIKELY.
IN THE NORTHERN OUTER WATERS, WIND SPEEDS ARE MODELED TO INCREASE
TO 20 TO 25 KNOTS WITH WAVE HEIGHTS REACHING 9 FEET AT A SHORT 8-
SECOND DOMINANT PERIOD LATE TONIGHT. THROUGHOUT THE NORTHERN
MARINE ZONES, STEEP SEAS WILL CREATE HAZARDOUS CONDITIONS FOR
SMALL CRAFT. AS A RESULT, SMALL CRAFT ADVISORIES HAVE BEEN ADDED
FOR THE NORTHERN MARINE ZONES, AS WELL, FOR THURSDAY AND FRIDAY.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 11 AM PDT
FRIDAY FOR PZZ415-450.
SMALL CRAFT ADVISORY UNTIL 10 PM PDT FRIDAY FOR PZZ455.
SMALL CRAFT ADVISORY UNTIL 10 PM PDT FRIDAY FOR PZZ470.
SMALL CRAFT ADVISORY UNTIL 5 AM PDT THURSDAY FOR PZZ475.
GALE WATCH FROM LATE TONIGHT THROUGH THURSDAY EVENING 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.
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