247
FXUS66 KEKA 202159
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
158 PM PST FRI NOV 20 2009
SYNOPSIS
A COLD FRONT WILL MOVE SOUTH OF THE AREA THIS EVENING
WITH RAIN SHOWERS...AND HIGHER ELEVATION SNOW...TO CONTINUE THROUGH
LATE TONIGHT. ANOTHER DISTURBANCE WILL BRING ADDITIONAL
PRECIPITATION TO NORTHWEST CALIFORNIA LATE SATURDAY INTO SUNDAY.
SNOW IS EXPECTED AT THE HIGHER ELEVATIONS. WARMER DRY WEATHER IS
EXPECTED FOR EARLY NEXT WEEK.
DISCUSSION
A COLD FRONT HAS MOVED SOUTHEAST OF THE CWA PER HPC
FRONTAL ANALYSIS...WITH A BAND OF HEAVIER SHOWERS MOVING AWAY FROM
THE AREA ALONG WITH THE FRONT. RAINFALL TOTALS FROM AROUND THE AREA
INCLUDE 1.54 INCHES IN CRESCENT CITY AND 2.02 IN HONEYDEW...WITH
MOST AREAS IN HUMBOLDT AND TRINITY REPORTING 0.70 TO 1.60 INCHES OF
PRECIP. IN MENDOCINO COUNTY RAINFALL TOTALS RANGE FROM 1.00 TO 1.50
INCHES ALONG THE COAST TO AROUND 1.00 INLAND. ONLY A FEW SNOW TOTALS
ARE AVAILABLE SO FAR...WITH INDICATIONS THAT A TRACE TO 1 INCH OF
SNOW FELL BETWEEN 2000 TO 3000 FT ACROSS TRINITY COUNTY AND THE
NORTHERN MOUNTAINS OF MENDOCINO. EXPECT THE SAME MAY BE TRUE FOR THE
FAR EASTERN HUMBOLDT MOUNTAINS SUCH AS SOUTH FORK PASS. SHOWERS WILL
CONTINUE BEHIND THE FRONT...WITH MODERATE SHOWERS POSSIBLE AT TIMES
THROUGH THE AFTERNOON AND EVENING. UNDER HEAVIER SHOWERS SNOW
FLURRIES MAY MIX DOWN TO NEAR 2000 FT OR BELOW. THAT SAID...THE
COASTAL HILLS MAY SEE A LIGHT DUSTING OF SNOW BUT FOR THE MOST PART
SNOW LEVEL WILL BE IN NEAR 2500 FT THROUGH THE NIGHT.
A VERY WEAK RIDGE WILL ALLOW PARTIAL CLEARING AND DRYING ON SATURDAY
AS TODAY'S STORM MOVES INTO THE GREAT BASIN...AND ANOTHER SHORT WAVE
TROUGH APPROACHES THE PACIFIC NORTHWEST. THE NEXT STORM APPEARS TO
BE QUITE VIGOROUS...BUT THE MAIN BULK OF ENERGY IS FORECAST TO TRACK
THROUGH THE PACIFIC NORTHWEST. UNDER THIS SCENARIO NORTHWEST
CALIFORNIA WILL BE ON THE SOUTHERN EDGE OF THE STORM...WITH A WARMER
AIR MASS AND QPF TOTALS ON THE ORDER OF 0.50 INCHES WITH LESS OVER
MENDOCINO AND UP TO 0.75 OVER THE SMITH RIVER BASIN.
THE LONGER TERM FORECAST SHOWS THE SUNDAY STORM MOVING INLAND FAIRLY
RAPIDLY SUNDAY NIGHT...WITH AN UPPER RIDGE DEVELOPING OVER THE E PAC
BY MONDAY. A SHORT WAVE TROUGH ON MONDAY WILL TRY TO BREAK DOWN THE
RIDGE BUT THE EFFECT SHOULD REMAIN WELL NORTH OF THE CWA. UPPER
RIDGING WILL THEN RETURN FOR TUESDAY AND WEDNESDAY. MODEL
CONSISTENCY IS SURPRISINGLY GOOD THROUGH EARLY TUESDAY...WITH
GFS...ECMWF AND CANADIAN IN FAIRLY CLOSE AGREEMENT IN STRENGTH AND
PLACEMENT OF FEATURES OVER THE EASTERN PACIFIC/GULF OF ALASKA
REGION. MORE SIGNIFICANT DIFFERENCES BEGIN TO APPEAR ON
WEDNESDAY...AS THE MODELS WORK ON BRINGING ANOTHER STRONG LOW
THROUGH THE GULF OF ALASKA. THE INDICATIONS ARE THAT A COLD FRONT
ASSOCIATED WITH THE LOW WILL SWING ACROSS THE PACIFIC NORTHWEST AND
NORTHERN CALIFORNIA THURSDAY INTO FRIDAY. THE GFS MAY BE SLOWING
DOWN THE TIMING WITH SUCCESSIVE RUNS...SO WILL NEED TO KEEP AN EYE
ON MODEL TIMING AND CONSISTENCY FOR THE HOLIDAY TIME PERIOD. CMC
MARINE
WESTERLY WINDS WILL DIMINISH TONIGHT BEHIND AN EXITING
COLD FRONT...HOWEVER A PERSISTENT WESTERLY SWELL WILL CONTINUE TO
RESULT IN HAZARDOUS CONDITIONS FOR SMALL CRAFT. ANOTHER TROUGH OF
LOW PRESSURE WILL BRING INCREASE WINDS AND BUILDING WAVES TO THE
WATERS FOR THE LATTER HALF OF SATURDAY AND SUNDAY...WHEN A SMALL
CRAFT ADVISORY CONTINUES. ENP/HANSON PLOTS SHOWING A LONGER PERIOD
SWELL TRAIN TO AFFECT THE WATERS BY MID WEEK. HENRY
AVIATION
MVFR CONDITIONS WITH SCT SHRA ARE EXPECTED TO CONTINUE
THROUGH LATE TONIGHT AS AN UPPER LEVEL LOW MOVES EASTWARD OVER THE
REGION. HIGH PRESSURE WILL BUILD INTO THE REGION FOR LATE TONIGHT
AND SATURDAY. CLEARING SKIES...RESIDUAL MOISTURE AND RADIATIONAL
COOLING MAY RESULT IN AREAS OF RADIATIONAL FOG WITH IFR/MVFR
CONDITIONS. HENRY
EKA WATCHES/WARNINGS/ADVISORIES
CA...WINTER WEATHER ADVISORY THROUGH MIDNIGHT PST TONIGHT FOR CAZ004.
NORTHWEST CALIFORNIA COASTAL WATERS...SMALL CRAFT ADVISORY FROM 4 PM
SATURDAY TO 4 PM PST SUNDAY FOR PZZ450.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST SATURDAY
FOR PZZ450.
SMALL CRAFT ADVISORY UNTIL 4 AM PST MONDAY FOR PZZ470-475.
SMALL CRAFT ADVISORY UNTIL 4 PM PST SUNDAY FOR PZZ455.
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