Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 312209
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
309 PM PDT FRI OCT 31 2014

.SYNOPSIS...COLDER AIR HAS FILTERED IN OVER NORTHWEST CALIFORNIA
BEHIND A COLD FRONT. SOME SHOWERS WILL CONTINUE TO IMPACT PORTIONS
OF NORTHWEST CALIFORNIA THROUGH SATURDAY AFTERNOON. OTHERWISE A
GENERAL DRYING TREND IS EXPECTED INTO SUNDAY. THE NEXT SYSTEM MAY
BRING SOME VERY LIGHT RAIN TO DEL NORTE AND NORTHERN HUMBOLDT
COUNTIES MONDAY AND TUESDAY.


&&

.DISCUSSION...THE COLD FRONT THAT BROUGHT RAIN LAST NIGHT AND THIS
MORNING HAS MOVED WELL INLAND AND SOUTH OF THE AREA LEAVING BEHIND
PARTLY TO MOSTLY CLOUDY SKIES. A FEW SHOWERS HAVE FORMED OVER THE
MOUNTAINS AS THE ATMOSPHERE HAS DESTABILIZED...BUT IN GENERAL NOT
MUCH HAS HAPPENED TODAY. THIS IS LIKELY BECAUSE THE REGION IS STUCK
BETWEEN JET MAXES IN AN AREA OF SUBSIDENCE BEHIND THE FRONT. MODELS
ARE INDICATING THAT THE BEST INSTABILITY WILL REMAIN JUST OFF THE
COAST WHILE THE UPPER LOW SLIDES SOUTH. THIS IS AN ADJUSTMENT FROM A
FEW DAYS AGO WHEN THE COLDEST AIR WAS FORECAST TO MOVE OVER
NORTHWEST CALIFORNIA. THUS CHANCES FOR THUNDERSTORMS FOR THE
REMAINDER OF THE AFTERNOON AND EVENING HOURS HAVE BEEN REMOVED OVER
LAND. THE JET ON THE BACKSIDE OF THE UPPER TROUGH WILL MOVE CLOSER
TO THE REGION ON SATURDAY...POSSIBLY BRING A FEW STRAY SHOWERS TO
THE REGION BEFORE CONDITIONS DRY OUT FOR SATURDAY NIGHT THROUGH
SUNDAY NIGHT.

MUCH COOLER AIR WILL CONTINUE TO MOVE INTO THE REGION BEHIND THE
COLD FRONT TONIGHT THROUGH SUNDAY. THIS WILL ALLOW OVERNIGHT LOW
TEMPERATURES TO DROP ACROSS THE INTERIOR...ESPECIALLY IN THE
VALLEYS. LOW LEVEL MOISTURE WILL LIKELY ALLOW FOG TO FORM...BUT IN
AREAS WHERE FOG DOES NOT FORM FROST IS EXPECTED IN TRINITY AND
EASTERN MENDOCINO COUNTIES SATURDAY AND SUNDAY NIGHTS. CONFIDENCE IN
FROST COVERAGE IS NOT HIGH AT THIS TIME SINCE FOG WILL BE A CONCERN.
HOWEVER SEVERAL VALLEYS IN TRINITY COUNTY...EVEN WITH THE FOG...MAY
FALL TO NEAR FREEZING SO THIS WILL NEED TO BE LOOKED AT CLOSELY OVER
THE NEXT 24 HOURS.

MODELS ARE IN GREAT AGREEMENT ON THE NEXT UPPER LEVEL SHORTWAVE
MOVING INTO THE PACIFIC NORTHWEST MONDAY INTO TUESDAY. THIS WAVE
WILL BE ACCOMPANIED BY A WARM FRONT WHICH WILL RESULT IN WARM AIR
ADVECTION OVER AREAS NORTH OF CAPE MENDOCINO. THE BEST UPPER LEVEL
DYNAMICS AND MOISTURE LOOKS TO BE AIMED NORTH OF HUMBOLDT BAY WITH
SLIGHT CHANCE TO CHANCE POTENTIAL FOR RAIN MONDAY AND TUESDAY IN DEL
NORTE COUNTY AND NORTHERN HUMBOLDT COUNTY.

UPPER LEVEL RIDGING WILL BUILD OVER THE WEST COAST ON WEDNESDAY
BRINGING A RETURN TO DRY CONDITIONS AND WARMER TEMPERATURES. HIGHS
WILL PUSH BACK INTO THE 70S IN MANY INTERIOR VALLEYS ONLY TO BE
COOLED BACK DOWN QUICKLY ON THURSDAY AS THE NEXT SYSTEM ARRIVES. THE
ECMWF INDICATES A MUCH MORE POTENT SYSTEM WITH ANOTHER ROUND OF RAIN
FOR THE AREA WHILE THE GFS WASHES THE FRONT OUT AS IT APPROACHES THE
COAST AND KEEPS MOST LOCATIONS DRY. THUS THERE IS SIGNIFICANTLY HIGH
UNCERTAINTY IN THE EXTENDED FORECAST. RPA


&&

.AVIATION...VFR CONDITIONS WITH TEMPORARY MVFR CONDITIONS AT TIMES
DUE TO REDUCED CEILINGS AS ISOLATED SHOWERS MOVE THROUGH THE AREA
WILL CONTINUE AT KCEC AND KACV THIS AFTERNOON AND EVENING. WINDS
WILL REMAIN LIGHT TO CALM THROUGH EARLY SATURDAY MORNING. PATCHY FOG
EARLY SATURDAY MORNING MAY REDUCE CEILINGS AND VISIBILITIES AT KCEC
AND KACV TO MVFR CONDITIONS. MVFR TO VFR CONDITIONS WILL CONTINUE AT
KUKI THROUGH TONIGHT. THE LOWER CONDITIONS ARE DUE TO ISOLATED
SHOWERS MOVING THROUGH THE AREA REDUCING CEILINGS AND/OR
VISIBILITIES. VFR CONDITIONS AND LIGHT WINDS TO CALM CONDITIONS WILL
OCCUR AT UKI SATURDAY.


&&

.MARINE...SEAS WILL CONTINUE TO INCREASE THIS EVENING AND TONIGHT IN
THE WAKE OF A WEAK COLD FRONT AND LOW PRESSURE TROUGH. SMALL CRAFT
ADVISORIES ARE IN EFFECT ACROSS ALL OF THE WATERS THIS AFTERNOON AND
SATURDAY DUE TO THE ELEVATED SEAS. WINDS WILL BECOME NORTHERLY BY
TONIGHT. THE SEAS WILL DIMINISH SUNDAY. HOWEVER THE SEAS WILL
INCREASE SLIGHTLY MONDAY AND TUESDAY AS A NORTHWESTERLY SWELL MOVES
ACROSS THE WATERS. WINDS WILL REMAIN LIGHT TO MODERATE THROUGH THE
MIDDLE OF NEXT WEEK.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY UNTIL 9 PM PDT SATURDAY FOR PZZ450-470.

     SMALL CRAFT ADVISORY UNTIL 2 AM PST SUNDAY FOR PZZ455-475.

&&

$$

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