146  
FXUS66 KEKA 222230  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
330 PM PDT FRI SEP 22 2017  
   
SYNOPSIS
 
FROST WILL ONCE AGAIN BE POSSIBLE ACROSS SOME INTERIOR  
VALLEYS TONIGHT, BUT A WARMING AND DRYING TREND IS EXPECTED TO  
UNFOLD BEGINNING TOMORROW. BY EARLY NEXT WEEK, TEMPERATURES ARE  
EXPECTED TO CLIMB BACK ABOVE NORMAL.  
 

 
   
DISCUSSION
 
AFTER AN EXTENDED WET AND COOL PERIOD THROUGHOUT THE  
REGION, A STEADY WARMING AND DRYING TREND IS EXPECTED TO UNFOLD  
OVER THE NEXT SEVERAL DAYS AS HIGH PRESSURE RECLAIMS THE WEST  
COAST. MUCH LIKE LAST NIGHT, FROST WILL AGAIN BE A POSSIBILITY  
ACROSS SEVERAL INTERIOR VALLEY LOCATIONS OVERNIGHT TONIGHT,  
PARTICULARLY IN TRINITY AND NORTHERN MENDOCINO COUNTIES. WHILE  
TEMPERATURES OVERALL ARE EXPECTED TO BE SLIGHTLY WARMER THAN THEY  
WERE THE NIGHT BEFORE, A FEW PROTECTED POCKETS WILL LIKELY SEE  
TEMPERATURES IN THE LOW TO MID 30S YET AGAIN. FROST POTENTIAL WILL  
STEADILY DIMINISH TOMORROW NIGHT AND BEYOND.  
 
TEMPERATURES WILL GRADUALLY CLIMB EACH DAY FROM SATURDAY  
UNTIL MONDAY, EVENTUALLY REACHING INTO THE 90S THROUGHOUT  
INTERIOR VALLEYS. INTERIOR TEMPERATURES WILL HOVER IN THE LOW TO  
MID 90S FROM MONDAY UNTIL AT LEAST FRIDAY, ALTHOUGH A VERY SLOW  
COOLING TREND IS EXPECTED TO CLOSE OUT THE WEEK. COASTAL  
TEMPERATURES ARE EXPECTED TO REACH SLIGHTLY ABOVE NORMAL THANKS  
TO THE DEVELOPMENT OF OFFSHORE WINDS, PARTICULARLY TUESDAY AND  
BEYOND AS THE INLAND THERMAL TROUGH SLIDES OFFSHORE IN RESPONSE TO  
AN APPROACHING UPPER LEVEL TROUGH. GIVEN THAT HIGH PRESSURE WILL  
DOMINATE AREA WEATHER FOR QUITE SOME TIME, PRECIPITATION WILL BE  
HARD TO COME BY FOR AT LEAST THE NEXT WEEK. /BRC  
 

 
   
AVIATION
 
A SLOW BUILDING RIDGE OF HIGH PRESSURE AND OFFSHORE  
FLOW WILL PRODUCE VFR CONDITIONS ACROSS MUCH OF NW CALIFORNIA'S  
AVIATION DISTRICT IN THE NEXT 24 HOURS. THE NORTHEASTERLY OFFSHORE  
FLOW WILL SURELY BE QUITE DETRIMENTAL TO ANY SIGNIFICANT MARINE  
LAYER CLOUD DEVELOP DURING THE TAF PERIOD TOO. TODAY HOWEVER,  
SKIES WERE MOSTLY CLEAR THIS MORNING EXCEPT AROUND HUMBOLDT BAY  
(AND A FEW OTHER PLACES) WHERE MORNING SHALLOW FOG/STRATUS BRIEFLY  
FORMED, BUT SWIFTLY DISSIPATED AROUND SUNRISE. ALSO, RESIDUAL  
MOISTURE ALLOWED FOR A FEW POCKETS OF FOG TO FORM ALONG SOME RIVER  
VALLEYS. INLAND AREAS: AS THE DEPARTING UPPER TROF SHIFTED  
EASTWARD...RESIDUAL MOISTURE, MOUNTAIN LIFT AND HEAT ENERGY CAUSED  
ENOUGH INSTABILITY TO PRODUCE SMALL CUMULUS BUILDUPS OVER  
INTERIOR RANGES. /TA  
 

 
   
MARINE
 
STRONG NORTHERLY WINDS HAVE BEGUN TO DEVELOP ACROSS THE  
WATERS TODAY, AND THESE WINDS WILL PERSIST THROUGH THE WEEKEND AND  
INTO THE MIDDLE OF NEXT WEEK. AS A RESULT, BUILDING STEEP SEAS CAN  
BE EXPECTED THROUGHOUT MUCH OF THE WATERS OVER THE NEXT SEVERAL  
DAYS. THE STRONGEST WINDS ARE EXPECTED TO BE LOCATED TO THE  
IMMEDIATE SOUTH OF PROMINENT CAPES AND POINTS, AS IS OFTEN THE  
CASE WITH NORTHERLY WINDS IN THIS REGION.  
 
BY WEDNESDAY, AN APPROACHING TROUGH OF LOW PRESSURE WILL HELP TO  
WEAKEN THE PRESSURE GRADIENT, AND WINDS WILL BEGIN TO SUBSIDE.  
AS A RESULT, STEEP SEAS WILL GRADUALLY SUBSIDE, AND RELATIVELY  
TRANQUIL CONDITIONS WILL DEVELOP FOR THE AND HALF OF THE WEEK.  
/BRC  
 

 
   
FIRE WEATHER
 
WARMING AND DRYING CONDITIONS ARE EXPECTED TO  
GRADUALLY UNFOLD THROUGHOUT THE REGION BETWEEN SATURDAY AND EARLY  
NEXT WEEK. WHILE MANY AREAS SAW CONSIDERABLE RAINFALL THIS PAST  
WEEK, PORTIONS OF EASTERN TRINITY AND MOST OF MENDOCINO AND LAKE  
COUNTIES DID NOT, AND FUELS HAVE THE POTENTIAL TO DRY QUICKLY.  
THIS WILL ESPECIALLY APPLY TO MONDAY AND TUESDAY, AS WELL ABOVE  
NORMAL TEMPERATURES ARE EXPECTED TO DEVELOP IN ADDITION TO GUSTY  
NOCTURNAL NORTHEASTERLY WINDS AT HIGH ELEVATIONS. WHILE THE WORST  
CONDITIONS ARE EXPECTED TO UNFOLD TO THE SOUTH AND EAST OF THE  
REGION, PERIODS OF CRITICAL FIRE WEATHER WILL BE POSSIBLE DURING  
THIS TIME FRAME. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH THE  
REST OF THE WEEK, BUT OFFSHORE WIND SPEEDS WILL BEGIN TO DIMINISH  
WEDNESDAY AND BEYOND. /BRC  
 

 
   
EKA WATCHES/WARNINGS/ADVISORIES
 
 
CA...FROST ADVISORY FROM 1 AM TO 8 AM PDT SATURDAY FOR CAZ107-108-110-  
111.  
 
NORTHWEST CALIFORNIA COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 8 PM PDT TUESDAY FOR PZZ470-475.  
 

 
 

 
 
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