000
FXUS66 KEKA 161039
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
339 AM PDT THU MAY 16 2013

.SYNOPSIS...LIGHT RAIN WILL DECREASE TO SHOWERS THIS MORNING AND
AFTERNOON AS A WEAK STORM SYSTEM MOVES THROUGH THE REGION. DRIER
AIR WILL ARRIVE ON FRIDAY. EXPECT A DRYING AND WARMING TREND THIS
WEEKEND WITH OVERNIGHT AND MORNING LOW CLOUDS AND FOG ALONG THE
COAST.

&&

.SHORT TERM...TODAY THROUGH SATURDAY.
A SHORTWAVE ROUNDING THE BASE OF AN UPPER LEVEL TROUGH WILL CONTINUE
TO MOVE THROUGH NORTHWEST CALIFORNIA TODAY. THE BEST UPLIFT ALONG
THE COAST WILL OCCUR VERY EARLY THIS MORNING AS A BAND OF LIGHT RAIN
CONTINUES TO MOVE ONSHORE. RAINFALL RATES IN THIS BAND HAVE RANGED
FROM A TRACE TO A FEW HUNDREDTHS OF AN INCH PER HOUR. RAIN CHANCES
WILL DECREASE THROUGH THE MORNING...BECOMING VERY LOW THIS AFTERNOON
AS THE TROUGH AXIS MOVES EAST. THE BAND OF RAIN ALONG THE COAST WILL
MOVE INLAND AND EAST OF THE ENTIRE CWA BY LATE THIS MORNING. WEAK
INSTABILITY OVER THE HIGHER TERRAIN...ASSOCIATED WITH THE COOLER AIR
ALOFT WITHIN THE TROUGH...WILL TRIGGER SOME AFTERNOON SHOWERS. LAPSE
RATES THROUGHOUT THE ATMOSPHERIC COLUMN WILL REMAIN WEAK SO NO
THUNDER IS ANTICIPATED.

THE TROUGH WILL BEGIN TO MOVE EAST OF THE AREA TONIGHT INTO FRIDAY
RAPIDLY DECREASING THE RAINFALL CHANCES FOR NORTHWEST CALIFORNIA. A
FEW SHOWERS MAY LINGER OVER THE MOUNTAINS FRIDAY AFTERNOON...BUT
GENERALLY FRIDAY WILL BE DRY WITH DECREASING CLOUD COVER AND
SLIGHTLY WARMER TEMPERATURES ACROSS THE INTERIOR. NORTHWEST ONSHORE
FLOW AT THE COAST WILL CONTINUE TO BRING HIGH BOUNDARY LAYER
MOISTURE TO COASTAL LOCATIONS RESULTING IN GREATER CLOUD COVERAGE
AND COOLER TEMPS.

ANOTHER SHORTWAVE WILL MOVE INTO THE PACIFIC NORTHWEST ON THE WEST
SIDE OF THE UPPER TROUGH AS THE TROUGH CONTINUES TO MOVE EAST INTO
THE INTERIOR ROCKIES ON SATURDAY. A WEAK FRONT ASSOCIATED WITH THIS
SHORTWAVE MAY BRING A FEW SHOWERS TO DEL NORTE COUNTY FOR SATURDAY
AFTERNOON. OTHERWISE DRY CONDITIONS WILL PERSIST ACROSS NORTHWEST
CALIFORNIA. INTERIOR VALLEY FOG/LOW CLOUDS WILL BE LIKELY SATURDAY
MORNING WITH LOW LEVEL MOISTURE FROM THE RAINS TODAY LINGERING
ACROSS THE REGION. ADDITIONALLY COASTAL STRATUS IS ANTICIPATED
...POSSIBLY THROUGHOUT THE DAY...AS NORTHWEST FLOW PERSISTS. RPA

.LONG TERM....SATURDAY NIGHT THROUGH THURSDAY.
SUNDAY AND MONDAY THE GFS AND ECMWF REMAIN IN GOOD AGREEMENT ON
HIGH PRESSURE BUILDING INTO THE REGION. OFFSHORE FLOW IS EXPECTED
TO SET UP WITH THIS HIGH PRESSURE KEEPING COASTAL CLOUDS TO A
MINIMUM. THIS WILL BRING GUSTY NORTHERLY WINDS OF 20 TO 30 MPH
SUNDAY THROUGH TUESDAY AFTERNOONS TO THE COAST. INLAND
TEMPERATURES WILL WARM AGAIN...PEAKING ON MONDAY IN THE MID TO
UPPER 80S. TUESDAY WILL BE NEARLY AS WARM. ALONG THE IMMEDIATE
COAST TEMPERATURES ARE EXPECTED TO REMAIN NEAR 60 WITH GUSTY
NORTHERLY WINDS KEEPING THEM A BIT COOLER THAN WOULD OTHERWISE BE
EXPECTED IN THIS OFFSHORE FLOW. TUESDAY NIGHT INTO WEDNESDAY THE
GFS AND ECMWF ARE IN GOOD AGREEMENT ON AN A FAIRLY DEEP UPPER
LEVEL TROUGH MOVING OVER THE AREA. CURRENT MODEL RUNS CONTINUE TO
SHOW THIS SYSTEM TO BE FAIRLY DRY...BUT PUT CLIMO POPS (SLIGHT
CHANCE) IN. THIS WILL NEED TO BE WATCHED. INLAND AREAS WILL SEE
SOME FAIRLY DRAMATIC COOLING WITH THIS TROUGH...AS MUCH AS 10 TO
20 DEGREES LOWER ON HIGH TEMPERATURES THAN MONDAY. SOME INLAND
AREAS COULD SEE SOME FROST...BUT THE EXACT STRENGTH AND POSITION
OF THE LOW WILL IMPACT THIS. THE BEST CHANCE LOOKS TO BE IN THE
VALLEYS OF TRINITY COUNTY. THURSDAY THIS TROUGH STARTS TO MOVE OUT
OF THE AREA. THERE BEGINS TO BE SOME SUBTLE DIFFERENCES IN THE GFS
AND ECMWF...BUT THEY OVERALL THEY AGREE ON THE PATTERN. MKK


&&

.AVIATION..A BAND OF RAIN HAS BROUGHT LOWER CIGS TO COASTAL
LOCATIONS THIS MORNING WITH LIFR OCCURRING AT CEC. AS THIS BAND
MOVES EAST...CIGS SHOULD LIFT SLIGHTLY INTO IFR OR MVFR FOR LATER
THIS MORNING. AN UPPER TROUGH WILL BEGIN TO MOVE EAST OF THE COAST
THIS AFTERNOON POSSIBLY MIXING OUT COASTAL STRATUS FOR A SHORT
PERIOD...BUT GENERALLY LOWER CIGS WITH MVFR OR LOWER CONDITIONS ARE
EXPECTED TO PREVAIL FOR COASTAL TERMINALS.

ACROSS THE INTERIOR LOWERING CIGS ARE EXPECTED TODAY WITH MVFR
POSSIBLE FOR TERMINALS NORTH OF MENDOCINO COUNTY. CLOUDS WILL LOWER
IN MENDOCINO COUNTY THROUGH THE DAY...BUT WITH LITTLE RAINFALL NOW
ANTICIPATED...CEILINGS WILL LIKELY STAY ABOVE MVFR THROUGH THE
AFTERNOON. SOME LOWER CLOUDS ARE MORE LIKELY TONIGHT AS HIGH AND MID
CLOUDS MOVE EAST...TEMPERATURES COOL AND LOW LEVEL RH REMAINS HIGH.
RPA


&&

.MARINE...TODAY A WEAK TROUGH IS MOVING ACROSS THE AREA. THIS IS
BRINGING LIGHT WINDS TO THE WATERS THIS MORNING. SEAS ARE CURRENTLY
AROUND 4 TO 5 FEET AT 10 SECONDS. THEY ARE EXPECTED TO PERSIST
THROUGH FRIDAY NIGHT. SATURDAY NORTHERLY WINDS AND SEAS WILL BEGIN
TO BUILD AS HIGH PRESSURE STARTS TO MOVE BACK INTO THE AREA.
CONFIDENCE IS BUILDING ON THE HIGH PRESSURE STRENGTHENING AND
BRINGING NEAR GALES TO GALES SUNDAY THROUGH TUESDAY. STEEP SHORT
PERIODS WAVES LOOK TO PEAK AROUND 14 FT ON MONDAY. BUMPED THE WINDS
UP TO BE IN LINE WITH MOST OF THE NEW MODEL GUIDANCE. THE GFS
CONTINUES TO SHOW SLIGHTLY HIGHER WINDS...BUT IT USUALLY RUNS A BIT
HIGH ON THE SURFACE WINDS.

MID-WEEK ANOTHER UPPER LEVEL TROUGH WHICH WILL DIMINISH THE WINDS ON
WEDNESDAY AND THURSDAY.

THE LONG PERIOD SOUTHERLY WAVE REMAINS FAIRLY CONSISTENT IN THE WAVE
WATCH MODEL. IT IS SHOWING IT BUILDING INTO THE AREA ON SATURDAY AT
AROUND 3 FT AT 20 SECONDS. BUOYS 51203 AND 51204 AROUND HAWAII HAVE
STARTED TO SHOW THIS SWELL. IT MAY BE COMING IN A BIT SLOWER THAN
PREVIOUSLY EXPECTED...BUT IT IS STILL THERE. THIS WILL NEED TO BE
MONITORED. MKK



&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...NONE.
&&

$$

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