871
FXUS66 KEKA 071144
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
344 AM PST SAT NOV 7 2009
SYNOPSIS
A WEAK DISTURBANCE WILL BRING SCATTERED SHOWERS TO THE
NORTH COAST TODAY...ALTHOUGH INTERVALS OF SUNSHINE CAN ALSO BE
EXPECTED. DRY WEATHER WILL RETURN SUNDAY BEFORE THE NEXT STORM
SYSTEM IMPACTS THE REGION LATE MONDAY INTO TUESDAY.
DISCUSSION
EARLY MORNING SATELLITE IMAGERY SHOWS A WEAK SHORTWAVE
MOVING INTO OREGON WITH A LARGE AND DEEP GULF OF ALASKA VORTEX
SLOWLY PUSHING EAST. AS THE TAIL END OF THE SHORTWAVE PUSHES
SOUTHEAST AND CLIPS NW CA THIS MORNING...LOW AND MID LEVEL
MOISTURE WILL INCREASE WITH A CHANCE OF SHOWERS AND INCREASED
CLOUDS...ESPECIALLY OVER DEL NORTE COUNTY. A FAIR AMOUNT OF SUN
CAN BE EXPECTED IN BETWEEN THE SHOWERS TODAY. COOLER AIR BEHIND
THE FRONT THAT PASSED YESTERDAY WILL KEEP TEMPERATURES NEAR
NORMAL TODAY. MOISTURE LESSENS RAPIDLY AT H85 AND ABOVE BY EARLY
AFTERNOON UNTIL THE NEXT EMBEDDED SHORTWAVE RESULTS IN SHALLOW
MOISTURE RETURN THIS EVENING AND EARLY TONIGHT. THE BEST LIFT AND
FORCING WITH BOTH SHORTWAVES WILL REMAIN WELL OFF TO THE NORTH SO
WE ANTICIPATE JUST SCATTERED SHOWERS AND RELATIVELY LOW QPF
THROUGH TONIGHT ALTHOUGH A FEW SHOWERS COULD BECOME LOCALLY
HEAVY. OTHERWISE...A LARGE LONG PERIOD NW SWELL FROM THE STRONG
LOW NEAR ALASKA WILL CONTINUE TO RESULT IN HIGH SURF AND BREAKER
HEIGHTS OVER 25 FEET ALONG THE REDWOOD AND MENDOCINO COASTS
THROUGH AT LEAST LATE TONIGHT.
FOR SUNDAY...RISING H5 HEIGHTS AND THICKNESSES SHOULD ENSURE A
MAINLY DRY ACROSS THE ENTIRE NORTH COAST. SOUTHWESTERLY FLOW
ALOFT INCREASES MARKEDLY LATE SUNDAY NIGHT INTO EARLY MONDAY IN
ADVANCE OF A DEEPER SHORTWAVE TROUGH AND COLD FRONT. THIS SYSTEM
WILL MOVE SLOWER THAN ITS PREDECESSORS AND BRING A CHANCE OF RAIN
MONDAY INTO TUESDAY...WITH THE BEST CHANCE MONDAY NIGHT INTO
EARLY TUESDAY BEHIND THE FRONT ITSELF...BEFORE IT BECOMES MORE
DIFFUSE.
A RATHER PROGRESSIVE PATTERN TO PERSIST THROUGH THE EXTENDED
PERIOD WITH BROAD BUT WEAK TROUGHING OVER THE PAC NW. RECENT
FORECAST MODELS SUGGEST ANOTHER STORM SYSTEM WILL THREATEN THE
REGION TOWARD THE END OF NEXT WEEK...ALTHOUGH THIS SOLUTION
VARIES FROM EARLIER MODEL RUNS. WE MAINTAINED SLIGHT CHANCE POPS
FOR THE EXTENDED. A SIGNIFICANT SPREAD AMONG MODEL ENSEMBLES ADDS
TO LOW CONFIDENCE AND UNCERTAINTY FOR THIS PERIOD. BETTWY
AVIATION
WEAK RIDGE EXTENDING INTO THE REGION FROM THE
SOUTHWEST WILL CREATE FAVORABLE CONDITIONS FOR IFR IN THE
INTERIOR VALLEYS...EARLY THIS MORNING AND AGAIN LATE TONIGHT
THROUGH EARLY SUNDAY MORNING. TAIL END OF A TROUGH WILL GENERATE
A FEW SPOTTY LIGHT SHOWERS AND OCCASIONAL MVFR
CONDITIONS...PRIMARILY ACROSS THE NORTH COAST THIS MORNING. DJB
MARINE
MAIN STORY CONTINUES TO BE THE LARGE NW SWELL. SWELL
PEAKED LATE AFTERNOON/EARLY EVENING YESTERDAY. HIGHEST REPORT WAS
FROM CDIP BUOY #13...COMING IN AT 27 FEET AT 17 SECONDS. ENP HAS
SWELL UP TO 18 FT AT 15 SECONDS CLEAR THROUGH SUNDAY AFTERNOON.
THE DURATION OF THE EVENT IS WAY TOO LONG AND HAVE SCALED HEIGHTS
DOWNWARD THROUGH SUNDAY. WITH SWELL PERIODS OF 15-17 SECONDS
THERE IS STILL A CHANCE FOR DANGEROUSLY HIGH SURF.
NEXT FRONT AND WIND EVENT IS EXPECTED MONDAY. GFS HAS WIND
RAMPING UP TO NEAR GALE - 30 KTS. GFS HAS BEEN INCONSISTENT ON
THE STRENGTH OF THE SOUTH WINDS...SO FOR NOW WILL STAY WITH 20-30
KTS. DJB
EKA WATCHES/WARNINGS/ADVISORIES
CA...HIGH SURF ADVISORY UNTIL 9 AM PST SUNDAY FOR CAZ001-002.
NORTHWEST CALIFORNIA COASTAL WATERS...
HAZARDOUS SEAS WARNING UNTIL 9 AM PST SUNDAY FOR PZZ450-455-470-
475.
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