Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 021200
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
500 AM PDT WED SEP 2 2015

.SYNOPSIS...TEMPERATURES WILL REMAIN NEAR OR BELOW NORMAL FOR THE
NEXT SEVERAL DAYS AS A TROUGH SITS OVER THE WEST COAST. A FEW
LIGHT SHOWERS ARE EXPECTED NORTH OF CAPE MENDOCINO TODAY...AND
ISOLATED SHOWERS OR THUNDERSTORMS ARE POSSIBLE OVER THE INTERIOR
ON FRIDAY. OTHERWISE...LITTLE TO NO RAIN IS EXPECTED.

&&

.DISCUSSION...AN UPPER TROF CONTINUES OVER THE PAC NW. ANOTHER
SHORTWAVE AND ATTENDANT SURFACE COLD FRONT ARE MAKING THEIR WAY
ACROSS THE N 1/2 OF THE AREA EARLY THIS MORNING. MULTI-LAYERED
CLOUDINESS IS AFFECTING AREAS N OF CAPE MENDOCINO...AND LIGHT RAIN
HAS BEEN REPORTED AT KCEC FOR ABOUT AN HOUR THUS FAR. RAINFALL
AMOUNTS HAVE BEEN LIGHT ALONG THE COAST. ONLY A FEW MORE
HUNDREDTHS ARE EXPECTED...WITH PERHAPS A TENTH OF AN INCH IN SOME
OF THE WINDWARD N DEL NORTE MOUNTAINS. IMPROVING CONDITIONS ARE
EXPECTED THIS AFTERNOON...WITH A FEW LINGERING SHOWERS OVER HIGHER
INLAND TERRAIN OF E DEL NORTE...N HUMBOLDT... AND N TRINITY
COUNTIES.

THE W COAST UPPER TROF IS FORECAST TO DIG THRU FRI NIGHT...THEN
LIFT NE RAPIDLY ON SAT AND SUN. AS THE TROF DIGS...AN UPPER LOW
WILL NEARLY CUT OFF IN THE BASE OF THE TROF OVER N CA. THIS
FEATURE WILL SUPPORT OUR NEXT CHANCE OF RAIN...ISOLATED TO LOW END
CHANCE SHOWERS OVER MAINLY THE INTERIOR FOR FRI INTO FRI NIGHT.
INCREASED INSTABILITY MAY SUPPORT AN ISOLATED THUNDERSTORM OR TWO
OVER TRINITY COUNTY FRI AFTERNOON AND EVENING. THE DEPARTING LOW
WILL LEAVE A WEAK...BAGGY TROF JUST SE OF THE AREA VERY EARLY NEXT
WEEK WITH MORE RIDGING EXPECTED THEREAFTER.

WITH THE TROF OVER THE W COAST...TEMPERATURES WILL REMAIN NEAR TO
BELOW NORMAL THRU SAT. TEMPERATURES WILL WARM TO ABOVE CLIMO OVER
THE INTERIOR BY NEXT WEEK. HAVE ADJUSTED DAYTIME HIGHS UPWARDS
ANOTHER DEGREE OR SO FOR THIS PERIOD TO COME MORE IN LINE WITH MOS
GUIDANCE. /SEC

&&

.AVIATION...A PASSING WEAK COLD FRONT WILL RESULT IN PERIODS OF
LIGHT RAIN AT COASTAL SITES THIS MORNING...WITH DIMINISHING
INTENSITY BY LATE MORNING. MVFR/IFR CIGS WILL LIKELY LIFT THIS
AFTERNOON...AND WITH OFFSHORE WINDS DEVELOPING OVERNIGHT THEY WILL
LIKELY STRUGGLE TO REDEVELOP...PARTICULARLY AT CEC. ACV WILL STAND
A BETTER CHANCE AT SEEING LOW CIGS AGAIN TONIGHT...BUT CONFIDENCE
IS LOW AT THIS STAGE AND WILL REPRESENT THIS POSSIBILITY WITH A
SCT MENTION FOR NOW. VFR CONDITIONS EXPECTED AT UKI. /BRC

&&

.MARINE...WINDS THROUGHOUT THE WATERS REMAINED MOSTLY LIGHT
OVERNIGHT...AND AS A RESULT THE SEA STATE CONTINUES TO BE
DOMINATED BY A MID PERIOD NORTHWESTERLY SWELL RUNNING AT ABOUT 6
TO 7 FEET AND 11 TO 12 SECONDS. THIS WILL BEGIN TO CHANGE LATER
TODAY..THOUGH...AS NORTHERLY WINDS WILL BEGIN TO RAMP UP FOLLOWING
THE PASSAGE OF A WEAK COLD FRONT DURING THE DAY TODAY. SOME LIGHT
RAIN WILL CONTINUE ACROSS THE NORTHERN WATERS THROUGH THE EARLY
AFTERNOON...BUT IS EXPECTED TO DISSIPATE GRADUALLY THROUGH THE DAY
AND WILL NOT PRESENT MUCH IN THE WAY OF IMPACTS.

WINDS ARE EXPECTED TO BEGIN RAMPING UP DURING THE AFTERNOON AS HIGH
PRESSURE NUDGES IN FROM THE WEST...AND WILL LIKELY REACH SMALL CRAFT
ADVISORY LEVELS IN THE LEE OF THE CAPE FIRST BEFORE SPREADING INTO
MUCH OF THE REMAINDER OF THE WATERS.  THUS...ADDED SMALL CRAFT
ADVISORIES FOR ALL WATERS...BEGINNING SOUTH OF THE CAPE AT 3 PM AND
NORTH OF THE CAPE AND 9 PM.  WINDS WILL LIKELY INCREASE INTO THE
FRESH TO STRONG CATEGORY BY OVERNIGHT TONIGHT...PERHAPS WITH A FEW
NEAR GALE FORCE GUSTS IN THE LEE OF CAPE MENDOCINO.  STEEPER
NORTHWESTERLY WIND WAVES WILL BUILD IN RESPONSE...WHICH WILL BE IN
ADDITION TO THE GRADUALLY DECAYING MID PERIOD NORTHWESTERLY SWELL
ALREADY PRESENT.  AS A RESULT...EXPECT SEAS TO REACH 8 TO 11 FEET BY
TOMORROW MORNING ACROSS MUCH OF THE WATERS...WITH A MIX OF PERIODS
RANGING FROM 6 OR 7 SECONDS TO 11 OR 12 SECONDS AS THE SHORTER
PERIOD WAVES GRADUALLY BUILD.  THESE SHORTER PERIOD WAVES ARE NOT
REFLECTED WELL IN THE COASTAL WATERS FORECAST PRODUCT...AND BOATERS
SHOULD BE AWARE THAT SEAS WILL LIKELY BE A BIT STEEPER THAN THE 10
TO 11 SECONDS LISTED THERE.  WINDS AND SEAS WILL LIKELY REMAIN
ELEVATED FOR THE FORESEEABLE FUTURE...ALTHOUGH A BRIEF MODEST
REDUCTION IN WIND SPEEDS AND SEAS WILL BE POSSIBLE FRIDAY BEFORE
RAMPING BACK UP AGAIN OVER THE WEEKEND. /BRC

&&

.FIRE WEATHER...LOW-LEVEL MOISTURE HAS AIDED IN RH RECOVERIES
TONIGHT...WITH LINGERING DRY AIR OVER THE MOUNTAIN RIDGES OF THE
TRINITY HORN AND THE YOLLA BOLLYS. RH VALUES WILL DROP ONCE AGAIN
ACROSS MANY OF THE INTERIOR RIDGES TONIGHT...BUT SUBSIDENCE IS NOT
EXPECTED TO BE AS STRONG AS OVER THE PAST 24-36 HOURS. LATER IN
THE WEEK...NIGHTTIME MOISTURE LEVELS WILL GRADUALLY INCREASE.
DRIER AIR IS EXPECTED EARLY NEXT WEEK AS WEAK OFFSHORE FLOW
DEVELOPS AND TEMPERATURES WARM.

AS MENTIONED ABOVE...A DIGGING UPPER TROF AND NEARLY CUT OFF LOW
MAY BRING ENOUGH INSTABILITY FOR AN ISOLATED THUNDERSTORM OR TWO
FRI AFTERNOON AND EVENING OVER TRINITY COUNTY...PERHAPS EXTENDING
S INTO THE YOLLA BOLLYS. /SEC

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 9 AM FRI
     FOR PZZ450-470.
     SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 AM FRI
     FOR PZZ455.
     SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM MON
     FOR PZZ475.

$$

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