916  
FXUS66 KEKA 022216  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
316 PM PDT TUE SEP 2 2025  
   
SYNOPSIS
 
ISOLATED DRY THUNDERSTORMS REMAIN POSSIBLE IN THE  
INTERIOR LATE THIS AFTERNOON AND EVENING. HOT TEMPERATURES LIKELY  
THROUGH WEDNESDAY FOR THE INTERIOR. STRATUS LIKELY FOR THE  
COASTAL AREAS WITH MARGINAL SHORT-LIVED CLEARING IN THE AFTERNOONS  
FOR THE COMING DAYS. ANOTHER UPPER LEVEL LOW/TROUGH WILL BRING A  
SLIGHT CHANCE OF SHOWERS, PERHAPS SOME THUNDERSTORMS, ACROSS THE  
NORTHERN PORTIONS OF THE AREA THURSDAY AND FRIDAY.  
 

 
   
DISCUSSION
 
AN UPPER LEVEL LOW/TROUGH CONTINUE TO APPROACHES  
SLOWLY FROM THE SOUTH TODAY, WHILE MOISTURE HAS SURGED ACROSS THE  
AREA. RADAR IMAGERY SHOWED SHOWERS FROM SOUTHEAST MOVING ACROSS  
TRINITY COUNTY, WHILE SURFACE OBSERVATIONS REPORTED FEW HUNDREDTHS  
OF AN INCH. CLOUDINESS WILL CONTINUE TO DIMINISH FROM SOUTH TO  
NORTH DURING THE NEXT HOUR OR SO, ALLOWING A SURFACE HEATING WITH  
HIGH TEMPERATURES RAPIDLY CLIMBING TO MID 90'S AND REACHING OR  
EXCEEDING 100F ACROSS THE INTERIOR. THE PROGRESSIVE AFOREMENTIONED  
DISTURBANCE WILL BRING AN INCREASING INSTABILITY AND BREEZY WINDS  
LATE THIS AFTERNOON AND EVENING. BREEZY EASTERLY WINDS HAVE BEEN  
DEVELOPED WITH GUSTS FROM 25 TO AROUND 30 MPH OVER THE HIGHER  
TERRAIN. DRY LOW LEVELS AND DCAPE OVER 1000 J/KG SUPPORT GUSTY  
OUTFLOW WINDS OF UP TO 40-60 MPH FOR ANY STORMS THAT DO FORM.  
 
TONIGHT, LINGERING CHANCES (15%) OF SHOWERS AND THUNDERSTORMS ARE  
EXPECTED OVER THE NORTHEASTERN PORTION OF TRINITY COUNTY WITH  
SHOWERS AS THE TROUGH CONTINUE TO MOVE NORTHWARD. CAMS SHOW WEAK  
RETURNS OVER THE TRINITY HORN WHILE MODERATE TO STRONG RETURNS  
FARTHER EAST AND NORTH OF THE AREA.  
 
ON WEDNESDAY, THE SHORTWAVE DISTURBANCE BEGINS TO MOVE NORTHWARD AND  
THE WEATHER QUIETS DOWN. AN APPROACHING UPPER LEVEL TROUGH IS  
EXPECTED TO GRADUALLY APPROACH THE AREA FROM THE WEST PUSHING THE  
WARMER AIR RIDGING OFF TO THE EAST. THIS MAY HELP TO WEAKEN THE  
LOW LEVEL INVERSION, ALLOWING A PERIOD OF CLEARING SKIES LONG THE  
COASTAL AREAS.  
 
THURSDAY AND FRIDAY, AN UPPER LEVEL LOW/TROUGH WILL APPROACHES  
THE AREA. THE WINDS ALOFT SHIFT TO THE SOUTHWEST. THIS WILL BRING  
A SLIGHT CHANCES (10-20%) OF SHOWERS ACROSS THE NORTHERN PORTION  
OF THE FORECAST AREA, ESPECIALLY FOR DEL NORTE COUNTY. GFS AND NAM  
SUGGEST AN INCREASING INSTABILITY OVER INTERIOR DEL NORTE AND  
NORTHERN TRINITY COUNTIES ON THURSDAY AND FRIDAY. SOUNDING MODELS  
SHOW ELEVATED INSTABILITY WITH AN INVERTED V OVER TRINITY COUNTY  
ON THURSDAY. TEMPERATURES ARE EXPECTED TO DIMINISH BY A DEGREE OR  
TWO IN MOST AREAS AND ANOTHER FEW DEGREES THURSDAY.  
 
ON FRIDAY AND SATURDAY, MORE SIGNIFICANT COOLING IS EXPECTED WITH  
INTERIOR HIGHS IN THE HIGH 80'S TO LOW 90'S FRIDAY AND THE 80S  
MAINLY ON SATURDAY. THE COASTAL INVERSION WILL BE FAIRLY WEAK BY  
THIS POINT AND IT MAY ALLOW THE COAST TO CLEAR OUT ALLOWING  
WEEKEND TEMPERATURES IN THE MID 60S. /ZVS  
 

 
   
AVIATION...18Z TAFS)
 
STRATUS OFFSHORE CONTINUES TO IMPACT THE  
COASTAL TERMINALS LATE THIS MORNING. SOME LIFTING AND SCATTERING IS  
ALREADY OCCURRING AROUND ACV, AND THIS IS LIKELY TO CONTINUE INTO  
THE AFTERNOON HOURS. LIGHT ONSHORE WINDS WILL SUPPORT STRATUS  
REMAINING RIGHT OFF THE COAST WITH BRIEF IFR IMPACTS POSSIBLE INTO  
THE EVENING. AN EDDY OFFSHORE CONTINUES TO REINFORCE STRATUS AT CEC,  
SO CONFIDENCE IS LOWER ON SIGNIFICANT IMPROVEMENT AT CEC THIS  
AFTERNOON. SOME BRIEF CLEARING IS STILL POSSIBLE, BUT IT WILL BE  
SHORT LIVED. MOST MODELS ARE SUGGESTING A SHALLOW MARINE LAYER AGAIN  
THIS EVENING AND OVERNIGHT, WITH LIFR CEILINGS AND VISIBILITIES.  
THERE IS SOME UNCERTAINTY AS AN AREA OF LOW PRESSURE MOVES OVERHEAD,  
WHICH MAY DEEPEN THE MARINE LAYER SLIGHTLY AND RAISE CEILING HEIGHTS  
FROM WHAT IS FORECAST. STILL THIS MAY ONLY RAISE CEILINGS FROM LIFR  
TO IFR. THE INTERIOR AREAS, INCLUDING UKI, REMAIN VFR WITH MAINLY  
HIGH CLOUDS AND BREEZY WINDS THIS AFTERNOON. THUNDERSTORM ACTIVITY  
IS LIKE TO REMAIN TO THE NORTH AND EAST THIS AFTERNOON AND EVENING,  
PRIMARILY IN TRINITY AND SISKIYOU COUNTIES. JB  
 

 
   
MARINE
 
NORTHERLY WINDS CONTINUE WITH GUSTS UP TO 25-35 KTS  
POSSIBLE IN THE LEE OF CAPE MENDOCINO THIS AFTERNOON. THE OUTER  
WATERS NORTH OF THE CAPE FORECAST TO SEE WIND GUSTS OF AROUND 15-20  
KTS, WHILE NEARSHORE AREAS CONTINUE TO SEE LIGHT WINDS. SEAS REMAIN  
STEEP IN THE OUTER WATERS. A BRIEF LULL IS POSSIBLE THIS EVENING AND  
OVERNIGHT NORTH OF CAPE MENDOCINO, BUT STEEP WAVES OF 6-7 FT RETURN  
BY WEDNESDAY MORNING.  
 
THE STRONG WINDS IN THE LEE OF THE CAPE START TO EASE SOMEWHAT  
TONIGHT INTO WEDNESDAY AS A LOW PRESSURE SYSTEM MOVES UP FROM THE  
SOUTH. STILL, NORTHERLY GUSTS OF 15-20 KTS ARE LIKELY IN THE OUTER  
WATERS WEDNESDAY AFTERNOON. BY THURSDAY, A BROAD TROUGH APPROACHES  
THE AREA FROM THE NORTH WHICH FINALLY EASES THE NORTHERLY WINDS,  
ESPECIALLY NORTH OF CAPE MENDOCINO. A SERIES OF SHORTWAVES LATE WEEK  
INTO THE WEEKEND WILL MAINTAIN MILDER CONDITIONS CONDITIONS. WINDS  
MAY TURN SOUTHERLY AT TIMES, DEPENDING ON HOW FAR SOUTH THE TROUGH  
DIPS. JB  
 

 
   
FIRE WEATHER
 
TEMPERATURES CLIMBING RAPIDLY TO ABOVE NORMAL  
ACROSS THE INTERIOR AS THE SURGE OF MOISTURE CONTINUES TO MOVE  
NORTHWARD AND THE SKY CLEAR OUT FROM SOUTH TO NORTH. THERE REMAIN  
SLIGHT CHANCE (15%) OF ISOLATED DRY THUNDERSTORMS IN THE INTERIOR  
THROUGH THIS EVENING WITH INCREASING INSTABILITY THIS AFTERNOON  
AND EVENING, PRIMARILY FOR TRINITY COUNTY. DIURNAL, TERRAIN  
DRIVEN WINDS FORECASTED WITH BREEZY AFTERNOON WINDS OUTSIDE OF ANY  
GUSTY WINDS FROM THUNDERSTORMS. GUSTY AND ERRATIC OUTFLOW WINDS  
OF 40 TO 60 MPH ARE POSSIBLE WITH ANY STORMS THAT DO FORM. EVEN  
IF NO STORMS FORM, FIRE DANGER IS EXPECTED TO INCREASE. THE  
OVERALL ATMOSPHERIC INSTABILITY WILL INCREASE VENTILATION/MIXING  
ALLOWING FOR MORE FIRE GROWTH AND THE POTENTIAL FOR PLUME  
DOMINATED POTENTIAL. THE HIGH MIXING HEIGHTS WILL ALSO MIX DOWN  
WIND GUSTS OF 25 TO 30 MPH IN THE HIGHER TERRAIN AND EXPOSED  
AREAS. A RED FLAG WARNING REMAIN IN EFFECT UNTIL 8PM PDT THIS  
EVENING FOR FIRE WEATHER ZONES 204 AND 283.  
 
WINDS TREND DOWNWARD WEDNESDAY, BUT WARM TEMPERATURES AND VERY LOW  
AFTERNOON RH WITH POOR OVERNIGHT RECOVERIES IN THE HIGH ELEVATIONS  
ARE FORECAST TO CONTINUE THROUGH THURSDAY. AN APPROACHING UPPER  
LEVEL LOW/TROUGH WILL BRING A SLIGHT CHANCES (10-20%) OF  
PRECIPITATION ACROSS THE NORTHERN PORTION OF THE AREA THURSDAY  
AND FRIDAY. THIS WILL BRING AN INCREASING INSTABILITY, WITH THE  
POTENTIAL OF ISOLATED THUNDERSTORMS ACROSS INTERIOR DEL NORTE AND  
NORTHERN TRINITY COUNTIES. COOLER WEATHER WITH BELOW NORMAL  
TEMPERATURES AND GENERALLY HIGHER RELATIVE HUMIDITY IS EXPECTED  
FOR THIS WEEKEND.  
 

 
   
EKA WATCHES/WARNINGS/ADVISORIES
 
 
CA...  
RED FLAG WARNING UNTIL 8 PM PDT THIS EVENING FOR CAZ204-283.  
 
NORTHWEST CALIFORNIA COASTAL WATERS...  
SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR  
PZZ455.  
 
SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR  
PZZ470.  
 
SMALL CRAFT ADVISORY FROM 3 AM WEDNESDAY TO 3 PM PDT  
THURSDAY FOR PZZ470.  
 
SMALL CRAFT ADVISORY UNTIL 3 PM PDT THURSDAY 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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