435  
FXUS66 KEKA 040710  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
1210 AM PDT SAT OCT 4 2025  
   
SYNOPSIS  
 
DRIER AND WARMER WEATHER IS FORECAST FOR THE NEXT SEVERAL DAYS AS  
A RIDGE OF HIGH PRESSURE BUILDS OVER THE WEST COAST. THE NEXT  
CHANCE FOR RAIN MAY BE LATE NEXT WEEK AS ANOTHER TROUGH APPROACHES  
THE REGION.  
 
 
   
DISCUSSION  
 
THE TROUGH AND UPPER LOW THAT BROUGHT RAIN SHOWERS TO NORTHWEST  
CALIFORNIA IS BEGINNING TO MOVE INLAND ALLOWING FOR DRIER AIR TO  
FILTER OVER THE AREA FROM THE NORTH. THIS DRIER AIR AND NORTHERLY  
FLOW HAS ENDED THE SHOWER ACTIVITY AND WE SHOULD GO INTO A DRIER  
PATTERN FOR THE NEXT SEVERAL DAYS. A SHORTWAVE DIVING SOUTH ON THE  
WEST SIDE OF THE DEPARTING LOW MAY BRING SOME CLOUD COVER AND A FEW  
SHOWERS TO AREAS JUST NORTH OF DEL NORTE COUNTY SATURDAY INTO  
SATURDAY NIGHT. HOWEVER, AS THE SHORTWAVE PASSES TO THE SOUTH, EAST-  
NORTHEASTERLY FLOW IS FORECAST TO DEVELOP RESULTING IN DRY, OFFSHORE  
WINDS AND WARMING TEMPERATURES ALOFT. THE VAST MAJORITY OF MODEL  
GUIDANCE IS INDICATING RIDGING WILL BUILD OVER THE REGION FOR EARLY  
NEXT WEEK WITH TEMPERATURES WARMING TO NEAR NORMAL ACROSS THE REGION  
SUNDAY THROUGH TUESDAY.  
 
THE NEXT WEATHER CHALLENGE COMES LATER IN THE WEEK WHEN AN UPPER LOW  
MAY CUT-OFF FROM THE FLOW OFF OF THE NORTHERN CALIFORNIA COAST. THE  
OPERATIONAL RUNS OF THE GFS AND ECMWF ARE BOTH PREDICTING THIS LOW  
TO BE PRESENT OFF OUR COAST AROUND THE 9TH OR 10TH. BEING THIS MANY  
DAYS OUT, HOWEVER, IT'S ESSENTIAL TO CHECK THE ENSEMBLE CLUSTER  
ANALYSIS TO SEE IF THE OPERATIONAL RUNS ARE OUTLIERS DESPITE THEIR  
CONSISTENCY. AND LO AND BEHOLD (NO PUN INTENDED), THE ECMWF  
OPERATIONAL RUN IS ONLY ONE OF 16% OF THE ECMWF ENSEMBLE INDICATING  
THIS OUTCOME. THE OTHER 84% EITHER TAKES THE LOW DOWN THE COAST AS A  
SLIDER OR NEVER CUTS THE LOW OFF AT ALL. THE GFS ENSEMBLE ON THE  
OTHER HAND, AND ALSO THE CANADIAN ENSEMBLE, IS MUCH MORE  
CONFIDENT IN THE CUT-OFF LOW SOLUTION WITH ABOUT 90% IN THIS CAMP.  
THUS, DESPITE THE OPERATIONAL RUN AGREEMENT, THERE REMAINS  
UNCERTAINTY AS TO THE FINAL TRAJECTORY OF THE LOW PRESSURE SYSTEM.  
REGARDLESS, RAIN CHANCES WILL BE ON THE INCREASE LATE WEEK AND  
DEPENDING ON THE LOWS PROGRESSION, COULD BRING WIDESPREAD WETTING  
RAINS TO THE REGION AND A PERIOD OF GUSTY SOUTH WINDS NEAR THE  
COAST. IF THE CUT-OFF LOW SOLUTION DEVELOPS, THE UPPER LEVELS MAY  
BE QUITE COLD RESULTING IN STEEP LAPSE RATES AND THE POTENTIAL FOR  
THUNDERSTORMS. RPA  
 
 
   
AVIATION  
 
LOW CLOUDS AND STRATUS ARE CURRENTLY VISIBLE ON SATELLITE OVER  
HUMBOLDT COUNTY AND AREAS OFF THE COAST. MVFR CEILINGS ARE BEING  
OBSERVED AT ACV WITH THIS DEEP MARINE LAYER. A WEAK MARINE  
INVERSION ALONG WITH OFFSHORE FLOW MAY KEEP THE DEL NORTE AND  
MENDOCINO COASTS CLEAR TONIGHT, THOUGH SOME BRIEF IMPACTS ARE  
POSSIBLE NEAR SUNRISE. GENERALLY, CEILINGS ARE FORECAST TO REMAIN  
MVFR WITH BRIEF PERIODS OF IFR. INLAND AREAS OUTSIDE HUMBOLDT WILL  
LARGELY REMAIN VFR OVERNIGHT INTO SATURDAY. WINDS ARE LIKELY TO  
BE GUSTY AGAIN ALONG THE COAST, WITH AFTERNOON GUSTS NEARING OR  
EXCEEDING 20 KTS. HIGHER GUSTS ARE POSSIBLE AT CEC. JB  
 
 
   
MARINE  
 
NORTHERLIES HAVE CONTINUED TO INCREASE EARLY THIS MORNING AND  
CONFIDENCE IS GROWING FOR GALE FORCE GUSTS IN THE SOUTHERN WATERS  
(SOUTH OF CAPE MENDOCINO) STARTING THIS MORNING. THESE ARE LIKELY  
TO CONTINUE INTO THE AFTERNOON AND INTO SUNDAY. ELSEWHERE, PEAK  
GUSTS TODAY RANGE BETWEEN 20-30 KTS. TONIGHT INTO SUNDAY MORNING,  
WINDS INCREASE FURTHER WITH GALES BRIEFLY POSSIBLE IN THE NORTHERN  
OUTER WATERS. NEARSHORE WATERS ARE UNLIKELY TO SEE GALES, EXCEPT  
AROUND CAPE MENDOCINO, BUT STEEP SEAS PROPAGATING NEARSHORE FROM  
THESE WINDS ARE POSSIBLE. GENERALLY, THE SEA STATE WILL BE  
DOMINATED BY SHORT PERIOD SEAS OF 5-9 FT THROUGH THE WEEKEND. HIGH  
PRESSURE WEAKENS BY SUNDAY AFTERNOON INTO EARLY WEEK, AND WINDS  
WILL LIKELY EASE. JB  
 
 
   
EKA WATCHES/WARNINGS/ADVISORIES  
 
CA...  
NONE.  
NORTHWEST CALIFORNIA COASTAL WATERS...  
SMALL CRAFT ADVISORY UNTIL 11 AM PDT SUNDAY FOR PZZ455.  
 
SMALL CRAFT ADVISORY UNTIL 3 AM PDT SUNDAY FOR PZZ470.  
 
GALE WARNING FROM 3 AM TO 11 AM PDT SUNDAY FOR PZZ470.  
 
SMALL CRAFT ADVISORY UNTIL 3 AM PDT EARLY THIS MORNING FOR  
PZZ475.  
 
GALE WARNING UNTIL 11 AM PDT SUNDAY 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  
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