Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 261245
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
445 AM PST WED NOV 26 2014

.SYNOPSIS...HIGH PRESSURE OVER THE REGION WILL MAINTAIN DRY WEATHER
CONDITIONS THROUGH TONIGHT. A SERIES OF STORMS WILL BRING A
RETURN OF WET WEATHER CONDITIONS DURING THE THANKSGIVING WEEKEND.

&&

.SHORT TERM (THROUGH SATURDAY)...HIGH PRESSURE WILL BRING ANOTHER
DRY AND MOSTLY SUNNY DAY TO NORTHWESTERN CA TODAY. INLAND VALLEYS
ARE SEEING SOME THICK FOG THIS MORNING...BUT WILL CLEAR OUT BY
MIDDAY AS WELL. TEMPERATURES THIS AFTERNOON WILL BE SIMILAR TO
YESTERDAY...FIVE TO 15 DEGREES ABOVE SEASONAL NORMALS.

WATER VAPOR SHOWS A COLD FRONT APPROACHING THE AREA. THIS WILL
BRING A SIGNIFICANT PATTERN CHANGE TO THE AREA ONCE IT MOVES
ONSHORE. MODELS ARE IN FAIRLY GOOD AGREEMENT ON THE TIMING OF THIS
RAINFALL STARTING IN THE MORNING ON THURSDAY IN DEL NORTE
COUNTY AND STALLING OUT OVER THE OREGON/CALIFORNIA BORDER FOR
MUCH OF THURSDAY BRINGING SIGNIFICANT RAIN TO DEL NORTE COUNTY
AND MUCH LIGHTER AMOUNTS IN NORTHERN HUMBOLDT COUNTY. RAPID RIVERS
RISES ARE POSSIBLE ON THE SMITH RIVER BY FRIDAY NIGHT...ALTHOUGH
NO FLOODING IS EXPECTED AT THIS TIME. SNOW LEVELS WILL BE HIGH
WITH THIS FRONT...6000 TO 7000 FT. LATE THURSDAY NIGHT INTO FRIDAY
MORNING THIS FRONT WILL START TO MOVE ACROSS THE AREA BRINGING
RAIN TO THE REST OF THE AREA. MODELS ARE IN GOOD AGREEMENT ON
WIDESPREAD RAIN FRIDAY AFTERNOON AND FRIDAY NIGHT. RAINFALL
AMOUNTS VARY QUITE A BIT BETWEEN MODELS...BUT IN GENERAL AMOUNT
LOOK TO BE MODERATE...ENOUGH TO CAUSE SOME RIVER RISES...BUT
FLOODING IS NOT EXPECTED. SATURDAY THE RAINFALL LOOKS TO TAPER OFF
IN THE AFTERNOON...ALTHOUGH THERE WILL LIKELY STILL BE SOME AREAS
OF RAIN. MKK

.LONG TERM (SATURDAY NIGHT THROUGH WEDNESDAY)...SATURDAY NIGHT THE
GFS AND ECMWF SHOW ANOTHER DISTURBANCE MOVING ONSHORE AND BRINGING
RAIN TO AREAS A BIT FARTHER SOUTH. THE GFS CENTERS IT OVER
MENDOCINO COUNTY...WHILE THE ECMWF HAS IT FARTHER SOUTH...OVER THE
SF BAY AREA. THERE IS GENERAL AGREEMENT ON SOME BREAKS IN THE RAIN
ON SUNDAY MORNING WITH THE NEXT SYSTEM SLOWING DOWN. THIS IS ABOUT
WHERE THE AGREEMENT IN THE MODELS COMES TO AN END. THE 00Z ECMWF
HAS STARTED TO CUT THIS SYSTEM OFF AND THEN SLOWLY MOVE IT ONSHORE
ON TUESDAY. THE 00Z GFS WAS MUCH FASTER AND MORE CONSISTENT WITH
PREVIOUS RUNS...SO FOR THE TIME BEING THE FORECAST REMAINS MUCH THE
SAME. HOWEVER THE 06Z GFS IS ALSO SLOWING THE SYSTEM DOWN AND
TRYING TO CUT OFF LIKE THE ECMWF...ALBEIT STILL MOVING IT THROUGH
FASTER THAN THE ECMWF. FOR NOW WENT WITH CHANCE POPS ON TUESDAY
AND TUESDAY NIGHT TO ACCOUNT FOR THE SLOWER ECMWF SOLUTION.
OVERALL CONFIDENCE IS VERY LOW STARTING ON MONDAY WITH
DRASTICALLY DIFFERENT TIMING ON THIS SYSTEM AND THE TENDENCY FOR
MODELS TO STRUGGLE WITH CUTOFF LOWS. MKK

&&

.AVIATION...MOSTLY VFR CONDITIONS WILL PREVAIL AGAIN TODAY AS VALLEY
FOG DISSIPATES AND POCKETS OF CLOUDS ALONG PARTS OF THE COAST ERODE
BY LATE THIS MORNING. HIGH CLOUD COVER WILL STREAM OVER THE REGION
AND INCREASE THROUGH THE DAY AS THE APPROACHING FRONT GETS CLOSER TO
THE COAST. CEILINGS WILL SLOWLY LOWER INTO THE AFTERNOON BUT ARE NOT
EXPECTED TO IMPACT AVIATION OPERATIONS UNTIL LATE IN THE TAF PERIOD.
CEILING AND SLIGHT VISIBILITY REDUCTIONS SHOULD REMAIN WITHIN THE
MVFR CATEGORY TONIGHT. KML

&&

.MARINE...SOUTHERLY WINDS WILL INCREASE ACROSS THE COASTAL WATERS
THIS AFTERNOON AHEAD OF AN APPROACHING FRONT. THE HIGHEST WINDS AND
STEEPEST SEAS WILL BE OFFSHORE NORTH OF CAPE MENDOCINO. AS A RESULT
A SMALL CRAFT ADVISORY WAS ISSUED FOR MARINE ZONE 470 BEGINNING THIS
AFTERNOON. WINDS SOUTH OF THE CAPE WILL BE WEAKER BUT SHOULD STILL
FLUCTUATE NEAR 20 KNOTS. A LARGE SW-W SWELL WILL BUILD ACROSS THE
WATERS ON THANKSGIVING DAY CAUSING THE SEA STATE TO RISE TO AROUND
10 T0 13 FT. A SMALL CRAFT ADVISORY WAS ADDED FOR MARINE ZONE 475
BEGINNING THURSDAY AFTERNOON FOR THE BUILDING SEA STATE. I HELD OFF
ON ISSUING ADVISORIES FOR THE INNER COASTAL WATERS AT THIS TIME BUT
THEY MAY BE NEEDED BY FRIDAY. WE WILL MONITOR THE SWELL FOR TIMING
OF ANY SUBSEQUENT ADVISORIES. SOUTHERLY WINDS WILL PERSIST THROUGH
THE WEEKEND AS THE LOW PRESSURE SYSTEM DIVES SOUTHWARD ALONG THE
WEST COAST. BY EARLY NEXT WEEK MODELS FALL COMPLETELY OUT OF PHASE
THUS LITTLE CHANGES WERE MADE LATE IN THE FORECAST. KML

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 PM PST
     FRIDAY FOR PZZ470.

     SMALL CRAFT ADVISORY FROM 3 PM THURSDAY TO 9 PM PST FRIDAY
     FOR PZZ475.

&&

$$

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