Weather Service Report


416 
FXUS66 KEKA 302239
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
339 PM PDT TUE SEP 30 2014

.SYNOPSIS....A DRYING AND WARMING TREND WILL BEGIN TODAY AND
CONTINUE THROUGH THE END OF THE WEEK AS A STRONG RIDGE OF HIGH
PRESSURE BUILDS ACROSS THE REGION.

&&

.SHORT TERM...IN THE WAKE OF THE COLD FRONT THAT MOVED PASSED THE
AREA LAST NIGHT GUSTY WINDS HAVE SET UP ALONG THE COAST AND SKIES
HAVE MOSTLY CLEAR. TONIGHT WITH CLEAR SKIES AND COOL TEMPERATURES
ALOFT SURFACE TEMPERATURES WILL DROP TO SOME OF THE COLDEST SO FAR
THIS FALL. GUSTY WINDS WILL PERSIST OVER THE RIDGETOPS...BUT THE
INTERIOR VALLEYS SHOULD DECOUPLE TONIGHT ONCE THE SUN GOES DOWN.
MOST VALLEYS WILL DROP INTO THE 40S BUT TRINITY COUNTY SHOULD SEE
A FEW OF THE COLDEST VALLEYS DROP INTO THE MID 30'S WHICH WILL
ALLOW SOME FROST TO FORM. CONFIDENCE IS LOW ON THIS AS DEWPOINTS
HAVE NOT DROPPED YET. WITH THE DRIER AIR AND SUBSIDENCE DEWPOINTS
ARE EXPECTED TO DROP RAPIDLY THIS AFTERNOON AND EVENING. ALSO THE
WINDS WILL NEED TO DECOUPLE IN THE VALLEYS AND THIS CAUSE A FEW
AREAS TO STAY WARMER THAN EXPECTED. WENT AHEAD AND ISSUED THE
FROST ADVISORY TO GET THE WORD OUT EVEN THOUGH CONFIDENCE IS LOW.
ALONG THE COAST THERE MAY BE A FEW AREAS OF PATCHY FOG...ALTHOUGH
THIS IS EXPECTED TO BE LIMITED TO AROUND HUMBOLDT AND ARCATA BAY
AS WELL AS THE EEL RIVER VALLEY. HIGH PRESSURE AND OFFSHORE FLOW
SHOULD KEEP THE REST OF THE COAST CLEAR.

OFFSHORE FLOW AND HIGH PRESSURE SHOULD PERSIST THROUGH THURSDAY.
TEMPERATURES INLAND WILL WARM A BIT EACH DAY. THURSDAY MORNING
WILL LIKELY BE A FEW DEGREES WARMER THAN WEDNESDAY MORNING AS THE
AIRMASS ALOFT WARMS SIGNIFICANTLY. MKK

.LONG TERM (FRI THRU TUE)...UPPER LEVEL RIDGING WILL DOMINATE THE
WEATHER ACROSS NORTHWEST CALIFORNIA THROUGH THE WEEKEND WITH DRY
CONDITIONS...MOSTLY CLEAR SKIES...AND ABOVE NORMAL TEMPERATURES.
THE WARMEST DAY LOOKS TO BE FRIDAY WITH HIGH TEMPERATURES ACROSS
INTERIOR VALLEYS A GOOD 5 TO 10 DEGREES ABOVE NORMAL FOR THIS TIME
OF YEAR. TEMPERATURES WILL GRADUALLY COOL TOWARDS MORE SEASONAL
VALUES BY MONDAY AND TUESDAY. MODELS CONTINUE TO INDICATE DRY
CONDITIONS THROUGH AT LEAST THE MIDDLE OF THE COMING WEEK AS
RIDGING PERSISTS OVER THE WEST COAST. STP

&&

.AVIATION....MORNING CLOUD COVER QUICKLY SCATTERED MAKING FOR A 
MOSTLY SUNNY DAY ACROSS NORTHERN CALIFORNIA. AFTERNOON WINDS BECAME 
GUSTY AS THE OFFSHORE RIDGE AND THERMAL TROUGH ALONG THE CALIFORNIA 
COAST INCREASED THE PRESSURE GRADIENT. DUE TO THIS SETUP, OFFSHORE 
FLOW WILL DEVELOP OVERNIGHT KEEPING NW CALIFORNIA MOSTLY CLEAR 
THROUGH TOMORROW MORNING. SOME GROUND FOG MAY DEVELOP AROUND 
HUMBOLDT BAY EARLY WEDNESDAY MORNING OTHERWISE EXPECT VFR TO PREVAIL 
THROUGH THE TAF PERIOD. THE ONLY AVIATION CONCERN IS THE POTENTIAL 
FOR LOW LEVEL WIND SHEAR AS THE WINDS DECOUPLE OVERNIGHT MAKING  
WINDS LIGHT NEAR THE SURFACE AND GUSTY ALOFT. \KML

&&

.MARINE...NORTHERLY WINDS INCREASED SUBSTANTIALLY THIS AFTERNOON AS 
AN OFFSHORE RIDGE INTERACTED WITH A THERMAL TROUGH ALONG THE 
CALIFORNIA COAST AND STRENGTHENED THE PRESSURE GRADIENT. THE 18Z 
ASCAT PASS SHOWED GALE FORCE WINDS SOUTH OF CAPE MENDOCINO. THERE 
WAS ONLY A SLIVER OF ASCAT DATA AVAILABLE FOR THE NORTHERN WATERS 
WHICH SHOWED WINDS IN LOWER TO MID 20 KT RANGE. THE HAZARDOUS SEAS 
WARNING WAS CONTINUED FOR THE NORTHERN OUTER WATERS AS GALE FORCE 
WINDS ARE EXPECTED TO REMAIN MARGINAL. NEVER THE LESS, SEAS WILL 
REMAIN STEEP AND WINDS WILL BE GUSTY THROUGH WEDNESDAY AFTERNOON. 

CONDITIONS WILL EASE STARTING THURSDAY THROUGH THE WEEKEND AS AN 
APPROACHING LOW PRESSURE SYSTEM CAUSES THE GRADIENT TO RELAX. OVER 
THE WEEKEND TWO SEPARATE LONG PERIOD WAVE SYSTEMS WILL IMPACT THE 
COASTAL WATERS...ONE OUT OF THE NW AND THE OTHER OUT OF THE SW. 
OTHERWISE THE FORECAST REMAINS WELL ON TRACK WITH GOOD CONSISTENCY 
IN THE MODELS AND LITTLE CHANGES WERE MADE IN THE EXTENDED
FORECAST. 

&&

.FIRE WEATHER...OFFSHORE FLOW RESULTING FROM BUILDING HIGH
PRESSURE IN THE PACIFIC NORTHWEST AND A STRENGTHENING THERMAL
TROUGH OVER CENTRAL CALIFORNIA HAS RESULTED IN GUSTY
NORTHEASTERLY WINDS IN THE HIGHER ELEVATIONS OF NORTHWEST
CALIFORNIA AND THIS IS EXPECTED TO CONTINUE THROUGH WEDNESDAY
MORNING. ADDITIONALLY...THE NORTHEAST FLOW WILL ALLOW MUCH DRIER
AIR TO FILTER INTO THE AREA. THIS WILL RESULT IN POOR RH
RECOVERIES ON RIDGETOPS EACH NIGHT AND LOW RH VALUES ACROSS THE
INTERIOR FALLING INTO THE TEENS OR POSSIBLY SINGLE DIGITS DURING
THE AFTERNOON HOURS WEDNESDAY THROUGH THE END OF THE WEEK. WITH
RECENT RAINFALL LIKELY REDUCING THE RECEPTIVENESS OF FUELS...THE
POTENTIAL FOR RAPID FIRE GROWTH IS CURRENTLY REDUCED. THUS ONLY A
HEADLINE FOR THE WIND AND LOW RH VALUES WILL BE INCLUDED IN THE
FIRE WEATHER FORECAST AT THIS TIME. MKK/RPA

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY UNTIL 3 AM PDT WEDNESDAY FOR PZZ450-455.

     SMALL CRAFT ADVISORY UNTIL 9 AM PDT THURSDAY FOR PZZ470.

     HAZARDOUS SEAS WARNING UNTIL 3 AM PDT THURSDAY FOR PZZ470.

     SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR PZZ475.

     GALE WARNING UNTIL 9 AM PDT WEDNESDAY FOR PZZ475.

&&

$$

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