776
FXUS66 KEKA 130539
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
1039 PM PDT WED AUG 12 2026
AVIATION 06Z UPDATE
STRATUS REMAINS ALONG MOST OF THE NORTH
COAST AS WELL AS MOST OF SOUTHERN MENDOCINO COASTLINE LEADING TO
CONTINUED IFR/LIFR CONDITIONS. SOUTHERLY WINDS NEAR THE COAST ARE
EXPECTED THROUGH THE OVERNIGHT HOURS AS IS -DZ WITHIN THE FOG.
WIDESPREAD CLEARING IS POSSIBLE FOR THURSDAY, BUT NOT EXPECTED
THROUGH MOST OF THE DAY. INLAND AREAS WILL EXPERIENCE CONTINUED
TERRAIN ENHANCED WINDS AND CLEAR SKIES THROUGH THE EVENING. AREAS
WITHIN THE TRINITY AND KLAMATH RIVER VALLEYS WILL BE SMOKEY
LEADING TO MOUNTAIN OBSCURATION AND SLANT/SFC VISIBILITY ISSUES
THROUGH THE WEEK AS WELL.
PREV DISCUSSION
/ISSUED 429 PM PDT WED AUG 12 2026/
WHAT HAS CHANGED...
DECREASED FORECAST THUNDERSTORM COVERAGE, OTHERWISE NO
SIGNIFICANT CHANGES TO THE FORECAST/DISCUSSION.
KEY MESSAGES...
* WARM, NEAR-NORMAL TEMPERATURES EXPECTED FOR THE INTERIOR TODAY.
COOLER TEMPERATURES ARE LIKELY LATE WEEK INTO THE WEEKEND.
* SMOKEY CONDITIONS LIKELY FROM THE MP18 FIRE, FOCUSED IN THE
TRINITY RIVER VALLEY.
* SLIGHT CHANCE OF INTERIOR THUNDERSTORMS THURSDAY INTO SATURDAY.
* MINOR COASTAL FLOODING IS POSSIBLE AROUND HUMBOLDT BAY AT THE
MIDNIGHT HIGH TIDE TONIGHT.
SYNOPSIS...INTERIOR TEMPERATURES TREND BELOW NORMAL LATE IN THE
WEEK. COASTAL AREAS CONTINUE TO HAVE NEAR NORMAL TEMPERATURES WITH
OVERNIGHT STRATUS CLEARING IN THE AFTERNOONS ALONG WITH BREEZY
NORTHWEST WINDS. THERE IS A SLIGHT CHANCE FOR DRY THUNDERSTORMS IN
THE INTERIOR THURSDAY AND INTO SATURDAY.
DISCUSSION...SMOKE FROM THE MP 18 FIRE CONTINUES TO IMPACT AIR
QUALITY OVER NORTHERN CALIFORNIA, PARTICULARLY IN THE INTERIOR
VALLEYS OF HUMBOLDT AND TRINITY COUNTIES. DEPENDING ON FIRE
CONTAINMENT, EXPECT A SIMILAR PATTERN TO CARRY THROUGH THE WEEK.
THE LOW LEVEL INVERSION IS SHOWING SIGNS OF WEAKENING AS MORE OF A
TROUGHING PATTERN DEVELOPS, AND THIS COMBINED WITH SOME
ATMOSPHERIC INSTABILITY WILL HELP CLEAR OUT THE SMOKE MORE
EFFICIENTLY OVER THE COMING AFTERNOONS.
THE TROUGHING WILL CONTINUE TO LOWER INTERIOR DAYTIME HIGHS.
TEMPERATURES WILL BE LOWERING TO BELOW NORMALS THROUGH THE EXTENDED
FORECAST. THE MARINE LAYER IS DEEPENING AND EXTENDING FARTHER
INLAND, AND WILL BE CONDUCIVE TO PRODUCING LIGHT DRIZZLE OVER THE
COMING DAYS.
THE BROAD TROUGHING AND EMBEDDED DISTURBANCES WILL ALSO BRING LOW
CHANCES FOR SOME SHOWERS OR PERHAPS DRY THUNDERSTORM ACTIVITY. A
WEAK SURGE OF MONSOON MOISTURE ASSOCIATED WITH A SHORTWAVE
DISTURBANCE MAY CLIP PORTIONS OF THE SOUTHERN ZONES THURSDAY, BUT
EVEN THE MOST AGGRESSIVE MODES KEEP THE BULK OF THE MOISTURE SE OF
LAKE COUNTY AT THIS TIME. THIS DAY WILL STILL BE WATCHED REGARDING
ANY DRY LIGHTNING POTENTIAL THROUGH TRINITY COUNTY (5-10%),
ESPECIALLY IF THE MOISTURE FLUX NUDGES NORTHWEST AT ALL.
A SECONDARY WAVE WILL MOVE NE OVER NORTHERN CALIFORNIA FRIDAY INTO
SATURDAY MORNING. THIS DISTURBANCE WILL CARRY HIGHER INSTABILITY AND
MOISTURE (THOUGH STILL MEAGER), GIVING A SLIGHTLY HIGHER CHANCE FOR
SOME THUNDERSTORM ACTIVITY. THIS IS MAINLY EXPECTED IN SISKIYOU
COUNTY, BUT COULD IMPACT PORTIONS OF SURROUNDING COUNTIES (5-10%
OVER TRINTY COUNTY NORTHWARD THROUGH FAR EASTERN DEL NORTE COUNTY,
AND 10-15% OVER SISKIYOU COUNTY AND FAR NORTHEAST DEL NORTE).
THERE WOULD BE A POTENTIAL FOR NOCTURNAL ACTIVITY LATE FRIDAY AS
WELL IF STORMS OCCUR AT ALL. THAT SAID, THIS IS STILL A VERY LOW
CONFIDENCE FORECAST; HOWEVER, IT WILL STILL BE WATCHED VERY
CLOSELY DUE TO HISTORICAL POOR MODEL HANDLING OF THE SETUP TYPE
AND THE IMPACT EVEN A LITTLE LIGHTNING WOULD HAVE REGARDING FIRE
POTENTIAL OVER THE VERY DRY VEGETATION. SMOKE FROM THE ONGOING
MP18 FIRE NEAR HOOPA WILL LIKELY DAMPEN INSTABILITY (CAPE) OVER
THE AFTERNOON HOURS.
MARINE...STRONG NORTHERLIES WITH GALE CONDITIONS CONTINUE IN THE
OUTER WATERS. THESE WINDS ARE GENERATED STEEP AND HAZARDOUS SEAS UP
TO 12 FT AT 10 TO 11 SECONDS. THESE LARGER SEAS WILL PERIODICALLY
MIGRATE INTO THE INNER WATERS FOLLOWING THE AFTERNOON/EVENING
STRONGER WIND SURGES. SEAS OF UP TO 11 FT HAVE OCCASIONALLY BEEN
OBSERVED AT THE NORTH SPIT BUOY. NORTHERLY WINDS WILL DROP BELOW
25KTS THURSDAY AFTERNOON AS TROUGHING ENTERS THE REGION. THE
NORTHERLIES WILL DROP MORE SUBSTANTIALLY FRIDAY AND ESPECIALLY
THROUGH THE WEEKEND AS TROUGHING WEAKENS THE PRESSURE GRADIENT.
FIRE WEATHER...MINIMUM RH AND OVERNIGHT RECOVERIES WILL CONTINUE TO
IMPROVE WITH MOISTENING WESTERLY FLOW AND LOWER DAYTIME HIGHS FROM
THE BREAKDOWN OF THE RIDGE OF HIGH PRESSURE. A TROUGHING PATTERN
THEN TAKES SHAPE, WHICH WILL MAINTAIN GOOD RECOVERIES AND ALSO
INCREASES CHANCES FOR A DEEPENED MARINE LAYER TO INFILTRATE FARTHER
INTO THE INTERIOR.
A WEAK SURGE OF MONSOON MOISTURE ASSOCIATED WITH A SHORTWAVE
DISTURBANCE MAY CLIP PORTIONS OF THE SOUTHERN ZONES THURSDAY, BUT
EVEN THE MOST AGGRESSIVE MODES KEEP THE BULK OF MOISTURE SE OF LAKE
COUNTY AT THIS TIME. THIS DAY WILL STILL BE WATCHED REGARDING ANY
DRY LIGHTNING POTENTIAL THROUGH TRINITY COUNTY (5 TO 10%),
ESPECIALLY IF THE MOISTURE FLUX NUDGES NORTHWEST AT ALL.
A SECONDARY WAVE WILL MOVE NE OVER NORTHERN CALIFORNIA FRIDAY INTO
SATURDAY MORNING. THIS DISTURBANCE WILL CARRY HIGHER INSTABILITY AND
MOISTURE (THOUGH STILL MEAGER), GIVING A SLIGHTLY HIGHER CHANCE FOR
SOME THUNDERSTORM ACTIVITY (5-10% OVER TRINTY COUNTY NORTHWARD
THROUGH FAR EASTERN DEL NORTE COUNTY, AND 15% OVER SISKIYOU COUNTY
AND FAR NORTHEAST DEL NORTE). THERE WOULD BE A POTENTIAL FOR
NOCTURNAL ACTIVITY LATE FRIDAY AS WELL IF STORMS OCCUR AT ALL. STORM
MOVEMENT FRIDAY WOULD BE TO THE NORTH/NORTHEAST AROUND 20 MPH.
SMOKE FROM THE ONGOING MP18 FIRE NEAR HOOPA WILL LIKELY DAMPEN
INSTABILITY (CAPE) OVER THE AFTERNOON HOURS, FURTHER LOWERING
CONFIDENCE ON THUNDERSTORM COVERAGE.
COASTAL FLOODING...MEASURED SEA LEVELS CONTINUE TO RUN APPROXIMATELY
0.7 TO 0.84 FT ABOVE THE PREDICTED TIDE LEVEL IN HUMBOLDT BAY.
THE TIDE GAGE AT THE NORTH SPIT MEASURED 8.82 FT AT THE HIGHEST
PEAK LAST NIGHT WITH A 0.84 FT ANOMALY WHICH DROVE THE PREDICTED
TIDE OF 7.98 FT NEAR THE COASTAL FLOOD ADVISORY RANGE OF 8.9. THE
PREDICTED HIGH TIDE OVERNIGHT WILL BE AROUND 7.84FT AND WITH A
SIMILAR ANOMALY IT WILL BE JUST UNDER THE CRITERIA FOR AN
ADVISORY, BUT THE WEAKENING NORTHERLY WINDS MAY SLIGHTLY ENHANCE
THE ANOMALY. /EYS
EKA WATCHES/WARNINGS/ADVISORIES
CA...
COASTAL FLOOD ADVISORY UNTIL 1 AM PDT THURSDAY FOR CAZ103.
NORTHWEST CALIFORNIA COASTAL WATERS...
COASTAL FLOOD ADVISORY UNTIL 1 AM PDT THURSDAY FOR PZZ415.
SMALL CRAFT ADVISORY UNTIL 9 AM PDT THURSDAY FOR PZZ450-455.
GALE WARNING UNTIL 9 AM PDT THURSDAY FOR PZZ470-475.
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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