837
FXUS66 KEKA 092037
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
137 PM PDT THU JUL 9 2026
KEY MESSAGES
* COASTAL STRATUS AND FOG: MARINE LOW CLOUDS AND AREAS OF FOG
WILL AFFECT THE IMMEDIATE COAST, BRINGING COOL DAYTIME
TEMPERATURES AND OVERNIGHT DAMPNESS.
* INTERIOR HEAT: AN UPPER-LEVEL RIDGE WILL EXPAND WESTWARD,
CAUSING TEMPERATURES TO RISE ABOVE NORMAL ACROSS INLAND VALLEYS
INCLUDING LAKE, TRINITY, AND INTERIOR MENDOCINO COUNTIES
THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK.
SYNOPSIS
SHALLOW COASTAL STRATUS AND FOG WILL PERSIST ALONG THE
IMMEDIATE COAST WITH LIMITED AFTERNOON CLEARING THROUGH FRIDAY,
WITH AREAS ONLY SLIGHTLY FURTHER INLAND THAN THE BEACHES
EXPERIENCING PERIODIC AFTERNOON CLEARING. INLAND AREAS WILL
REMAIN DRY AND HOT UNDER A BUILDING UPPER- LEVEL RIDGE.
DISCUSSION
AN UPPER-LEVEL RIDGE OVER THE SOUTHWEST US IS
EXPANDING WESTWARD OVER NORTHWEST CALIFORNIA. SUBSIDENCE ALOFT IS
COMPRESSING THE MARINE LAYER, KEEPING IT SHALLOW AND CONFINED TO
THE COAST AND ADJACENT LOWER VALLEYS OVERNIGHT TO EARLY/MID
MORNING. INLAND AREAS WILL EXPERIENCE WARMING, WITH AFTERNOON
HIGH TEMPERATURES IN THE MID TO UPPER 90S BECOMING WIDESPREAD
ACROSS THE INTERIOR VALLEYS OF TRINITY, MENDOCINO, AND LAKE
COUNTIES THIS AFTERNOON.
EARLY NEXT WEEK, THE PLACEMENT OF THE UPPER RIDGE WILL DETERMINE
THE TRACK OF POTENTIAL MONSOONAL MOISTURE. CURRENT GUIDANCE
INDICATES A CONTINUING WARMING TREND FOR THE INTERIOR, WITH A LOW
PROBABILITY OF THUNDERSTORM DEVELOPMENT OVER NORTHEASTERN TRINITY
COUNTY.
AVIATION
AS HIGH PRESSURE BUILDS INTO THE AREA, A VERY TYPICAL
SUMMER PATTERN WILL TAKE HOLD OF TERMINALS IN NORTHWEST
CALIFORNIA. SHALLOW, DIURNAL COASTAL STRATUS WILL CONTINUE TO
AFFECT COASTAL TERMINALS WITH OVERNIGHT AND EARLY MORNING
CONDITIONS AT LIFR/IFR AND AFTERNOON/EVENING CONDITIONS AT VFR.
WINDS ALONG THE NORTHERN HUMBOLDT AND DEL NORTE COASTS WILL MOST
LIKELY HAVE NIGHTLY REVERSAL WINDS (WINDS FROM THE SOUTH). INLAND
TERMINALS WILL REMAIN VFR THROUGH THE TAF PERIOD.
MARINE
THE SURFACE PRESSURE GRADIENT BETWEEN AN OFFSHORE
SURFACE HIGH PRESSURE SYSTEM AND AN INLAND SURFACE THERMAL LOW IS
TIGHTENING. SOUTH OF CAPE MENDOCINO, SUSTAINED NORTHWEST WINDS OF
20 TO 25 KNOTS ARE GENERATING STEEP, WIND-DRIVEN SEAS. A GALE
WARNING FOR THE SOUTHERN OUTER WATERS IS OUT STARTING AT 5PM
TODAY TO 8AM FRIDAY MORNING DUE TO POTENTIAL GUSTS UP TO 40
KNOTS. FOR THE NORTHERN OUTER WATERS, WINDS OF 20 TO 25 KNOTS
COMBINED WITH STEEP 9-FOOT WAVES AT SHORT 8-SECOND PERIODS SATISFY
ADVISORY CRITERIA. ALL COASTAL MARINE ZONES ARE CURRENTLY UNDER A
SMALL CRAFT ADVISORY.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 11 AM PDT FRIDAY FOR PZZ415-450.
SMALL CRAFT ADVISORY UNTIL 10 PM PDT FRIDAY FOR PZZ455-470.
SMALL CRAFT ADVISORY UNTIL 5 PM PDT THIS AFTERNOON FOR
PZZ475.
GALE WARNING FROM 5 PM THIS AFTERNOON TO 8 AM 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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