Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 201255
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
455 AM PST SAT DEC 20 2014

.SYNOPSIS...A WARM FRONT WILL BRING RAIN TO THE REGION THROUGH
THE WEEKEND. HEAVY RAIN IS EXPECTED TODAY.  THEN...BUILDING HIGH
PRESSURE WILL DRY THE AREA OUT EARLY NEXT WEEK.

&&

.DISCUSSION...THE INITIAL WARM FRONT HAS MOVED OVER THE AREA.
STRONG WARM AIR ADVECTION AND DEEP MOISTURE WILL CONTINUE TO
STREAM OVER THE AREA TODAY BRINGING RAIN TO THE AREA. RAIN IS
CURRENTLY FALLING ACROSS THE ENTIRE AREA. THE HEAVIEST RAIN IS
DEFINITELY IN DEL NORTE COUNTY WHERE OVER AN INCH HAS FALLEN FROM
5PM THROUGH 4AM. MUCH LIGHTER AMOUNTS WERE REPORTED ELSEWHERE.
TONIGHT THIS PLUME OF MOISTURE STARTS TO SHIFT TO THE NORTH.
SUNDAY RAIN WILL CONTINUE IN DEL NORTE COUNTY WITH VERY LIGHT
RAIN OR DRIZZLE ELSEWHERE. MODELS ARE STILL IN SLIGHT
DISAGREEMENT ON EXACTLY HOW FAR NORTH IT WILL SHIFT ON SUNDAY BUT
GENERALLY TOOK A BLEND OF THE MODELS. ADDITIONAL RAINFALL AMOUNTS
ARE EXPECTED TO RANGE FROM 3.5 INCHES IN THE HILLS OF DEL NORTE
COUNTY TO AROUND A HALF INCH IN SOUTHERN MENDOCINO COUNTY AND
EASTERN TRINITY COUNTY. AROUND AN INCH IS EXPECTED IN THE HUMBOLDT
BAY REGION. NO RIVER IS EXPECTED AT THIS POINT...ALTHOUGH A SLIGHT
SHIFT IN THE STRENGTH OR DURATION COULD BRING SOME MINOR FLOODING
TO THE SMITH RIVER. SNOW LEVELS ARE CURRENTLY AROUND 5000 FEET AND
WILL CONTINUE TO BUILD THROUGH THE WEEKEND.

MONDAY AND TUESDAY HEIGHTS CONTINUE TO BUILD OVER THE AREA WITH
CONDITIONS STARTING TO DRY OUT. MONDAY IN THE NORTH SKIES WILL
LIKELY BE SLOW TO CLEAR OUT AND THERE MAY BE SOME LINGERING
DRIZZLE. ANY AREAS THAT DO MANAGE TO CLEAR OUT WILL LIKELY SEE
WIDESPREAD VALLEY FOG. BY TUESDAY MOST OF THE MID LEVEL CLOUDS
SHOULD BE GONE...HOWEVER WIDESPREAD VALLEY FOG IS LIKELY.
TEMPERATURES WILL BE SLOW TO WARM IN THESE INTERIOR VALLEYS AS
WELL AND THEY MAY NOT MAKE IT INTO THE 50S.

WEDNESDAY THERE CONTINUES TO BE SOME DIFFERENCES IN THE MODELS
WITH THE NEXT SYSTEM. THE 00Z ECMWF HAS MORE PRECIP AND IS QUITE A
BIT COLDER. THE ECMWF SOLUTION COULD BRING SEVERAL INCHES OF SNOW
AS LOW AS 3500 FT IN TRINITY COUNTY...WHILE THE 00Z GFS WOULD
BRING A LESS THAN AN INCH OF SNOW ABOVE 5000 FEET. CONTINUED WITH
A BLEND OF THE MODELS AND MADE FEW CHANGES TO THE FORECAST. AT
THIS POINT IT IS DIFFICULT TO CHOOSE A MODEL. THE GFS HAS
CONTINUED TO TREND WARMER...WHILE THE ECMWF CONTINUES TO BOUNCE
AROUND. BOTH MODELS DO AGREE THAT ANY COLD SNAP WILL BE SHORT
LIVED.

THURSDAY LEFT SOME SLIGHT CHANCE POPS IN PLACE...ALTHOUGH IT
GENERALLY LOOKS LIKE THE RIDGE IS BUILDING IN AND IT WILL BE
DRY FOR CHRISTMAS. FRIDAY MODELS ARE IN GOOD AGREEMENT ON THE
RIDGE BUILD IN AND DRY CONDITIONS ACROSS THE AREA. SATURDAY THE
GFS KEEPS THE RIDGE IN PLACE AND STILL LOOKS LIKE IT WILL BE
DRY...HOWEVER THE ECMWF IS HINTING AT A SHORTWAVE TROUGH MOVING
OVER THE TOP OF THE RIDGE AND THE CANADIAN ACTUALLY BRINGS A FRONT
OVER THE AREA. THIS WILL NEED TO BE MONITORED AS IT GETS CLOSER.
MKK

&&

.AVIATION...MORNING RADAR SHOWS RAIN ACROSS MOST OF NORTHWEST
CALIFORNIA. THIS RAIN IS ASSOCIATED WITH AN APPROACHING FRONT THAT
WILL CROSS THE REGION TODAY. EXPECT MVFR TO PREVAIL. THOUGH, PERIODS
OF IFR IS LIKELY IN SOME OF THE HEAVIER RAIN BANDS. ADDITIONALLY,
GUSTY SOUTHERLY WINDS ARE EXPECTED AHEAD OF THE FRONT TODAY,
ESPECIALLY ALONG THE REDWOOD COAST AND OVER THE HIGHER TERRAIN.

&&

.MARINE...THE MORNING BUOY OBSERVATIONS SHOW GUSTY SOUTHERLY WINDS.
WAVE HEIGHTS RANGE FROM 17-20 FT WITH MIXED SEAS, SHORT PERIOD WIND-
DRIVEN WAVES FROM THE SOUTH AND LONGER PERIOD WESTERLY SWELL. THE
0535Z ASCAT PASS SHOWED WINDS OF 20-25 KT NORTH OF CAPE MENDOCINO
AND WINDS OF 10-20 KT SOUTH OF IT. THESE CONDITIONS ARE ASSOCIATED
WITH AN APPROACHING FRONT. A FEW GUSTS TO GALE FORCE ARE NOT OUT OF
THE QUESTION NORTH OF CAPE MENDOCINO THIS MORNING, BUT DON`T EXPECT
THEM TO BE LONG ENOUGH IN TIME OVER A LARGE ENOUGH AREA TO WARRANT A
GL.W. IN ADDITION TO THE WINDS IS THE LONG PERIOD WESTERLY SWELL,
WHICH IS CURRENTLY PEAKING. SWELL DECAY CALCULATIONS BASED ON
OFFSHORE BUOY #2 HAS THE SWELL GRADUALLY SUBSIDING TODAY. THESE
CALCULATIONS INDICATE THE SE.W (HAZ SEAS WARNING) AND SU.Y (HIGH
SURF ADVISORY) IS ON TRACK TO EXPIRE THIS MORNING AND AFTERNOON
RESPECTIVELY. BUT WOULDN`T BE SURPRISED TO SEE ONE OR BOTH
EXTENDED A FEW HOURS IF THE LOCAL BUOY OBSERVATIONS SHOW
OTHERWISE. SC.Y`S (SMALL CRAFT ADVISORIES) WILL THEN BE UP FOR
THE SEAS THROUGH EARLY NEXT WEEK. EXPECT THE SOUTHERLY WINDS AND
WAVES TO IMPROVE THIS EVENING AND TONIGHT AS THE FRONT MOVES
INLAND. THE SAME CAN BE SAID OF THE WESTERLY SWELL, WHICH WILL
SLOWLY SUBSIDE THIS WEEKEND. MODELS ARE IN GOOD AGREEMENT SHOWING
LIGHTER WINDS EARLY NEXT WEEK AS HIGH PRESSURE BUILDS OVER THE
REGION. THE CONSMODEL SHOWS THE PRESSURE GRADIENT STRENGTHENING
SOUTH OF CAPE MENDOCINO LATE MONDAY INTO TUESDAY FOLLOWED BE NEAR
GALES AGAIN TOWARDS THE SECOND HALF OF NEXT WEEK. THE FORECAST
REFLECTS THIS.

&&

.SURF ZONE...A HIGH SURF ADVISORY REMAINS IN EFFECT THRU THIS
AFTERNOON FOR OUR ENTIRE COASTLINE. BREAKERS ARE LIKELY AROUND 22
TO 25 FT AT THE PRESENT TIME. THESE BREAKERS WILL SLOWLY DIMINISH
THROUGH THE DAY TODAY DROPPING TO 16 TO 21 FT BY LATE THIS
AFTERNOON. MKK/SEC

&&

.COASTAL FLOODING...ASTRONOMICAL TIDES WILL BE HIGH TODAY AND WITH
THE SOUTHERLY WINDS WATER LEVELS ARE RUNNING AROUND 1 FOOT HIGHER
THAN ASTRONOMICAL. THIS INDICATES THAT THERE WILL BE MINOR SALT
WATER FLOODING IN KING SALMON AND IN THE ARCATA BOTTOMS. ALONG THE
COAST THAT IS NOT PROTECT BY THE BAY HIGH SURF WILL LIKELY PUSH
THE WATER LEVELS HIGHER. THIS MAY IMPACT AREAS IN THE CRESCENT
CITY HARBOR. THERE IS THE POSSIBILITY THAT THE COMBINATION OF THE
HIGH SURF AND GUSTY SOUTH WINDS SOME WATER MAY REACH HWY 101 IN
THE EXPOSED AREAS. THIS WILL NEED TO BE MONITORED. THE MENDOCINO
COUNTY COAST MAY ALSO SEE THE HIGH SURF PUSH WATER UP INTO LOW
LYING AREAS. THIS WOULD MAINLY BE CAMPGROUNDS IN THE RIVER VALLEYS
AT THE COAST AND LOW LYING ROADS ALONG THE IMMEDIATE COAST.
CONFIDENCE IS LOW ON THIS AND IT WILL NEED TO BE MONITORED. HIGH
ASTRONOMICAL TIDES WILL CONTINUE...PEAKING ON MONDAY. HOWEVER
SOUTHERLY WINDS WILL DIMINISH SO THE OVERALL MAY NOT INCREASE TOO
MUCH. MKK

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     HIGH SURF ADVISORY UNTIL 6 PM PST THIS EVENING FOR CAZ001-002.

     COASTAL FLOOD ADVISORY FROM 8 AM THIS MORNING TO NOON PST
     TODAY FOR CAZ001.

     COASTAL FLOOD ADVISORY FROM 8 AM TO 11 AM PST THIS MORNING
     FOR CAZ002.

NORTHWEST CALIFORNIA COASTAL WATERS...
     HAZARDOUS SEAS WARNING UNTIL 9 AM PST THIS MORNING
     FOR PZZ450-455-470-475.

    SMALL CRAFT ADVISORY UNTIL 3 PM PST MONDAY FOR PZZ470.

    SMALL CRAFT ADVISORY UNTIL 3 PM PST MONDAY FOR PZZ475.

&&

$$

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