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000
FXUS66 KEKA 092352
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
352 PM PST MON DEC 9 2013

.SYNOPSIS...COLD WEATHER CONDITIONS WILL SLOWLY MODERATE THROUGH
MID WEEK. A WEAK FRONT WILL BRING AN INCREASE IN MOISTURE AND A
CHANCE OF LIGHT RAIN TOWARD THE END OF THE WEEK...PRIMARILY NORTH
OF CAPE MENDOCINO.

&&

.DISCUSSION...CLEAR SKIES PREVAILED ACROSS THE REGION AGAIN TODAY.
THERE WERE A FEW PATCHES OF FOG AND LOW OVERCAST IN THE INTERIOR
VALLEYS AGAIN THIS MORNING. IT WAS NOT AS EXTENSIVE AS YESTERDAY
MORNING AND BURNED OFF FASTER. THE BOUNDARY LAYER SHOULD DRY OUT
A BIT MORE TONIGHT. LOCAL MOISTURE SOURCES WILL PROBABLY BE
SUFFICIENT TO ALLOW MORE PATCHES OF FOG TO FORM INLAND AGAIN TONIGHT.
TEMPERATURES SHOULD BE HIGHER TONIGHT AS A RIDGE ALOFT BUILDS IN
FROM THE WEST. THE WARMING ALOFT WILL MOST LIKELY SHOW UP ACROSS
THE HIGHER ELEVATIONS. WITH DEW POINTS IN THE TEENS AND 20S AS OF
3PM...THE VALLEYS WILL STILL BE COLD TONIGHT. SLOW MODIFICATION OF
THE ARCTIC AIR MASS WILL CONTINUE THROUGH MID WEEK AS OFFSHORE
FLOW WEAKENS AND A RIDGE ALOFT BRINGS GREATER WARMING EACH DAY. A
WEAK SHORT-WAVE TROUGH WILL RIDE OVER THE RIDGE ON TUESDAY AND
PROBABLY SPREAD SOME HIGH LEVEL CLOUDS OVER THE REGION. THE NAM12
AND GFS DO SHOW BETTER ONSHORE FLOW TUESDAY INTO WEDNESDAY FOR
PERHAPS FOG AND LOW CLOUD PRODUCTION ALONG THE COAST. NAM12
X-SECTIONS INDICATE AN INVERSION SETTING UP ON TUESDAY AND THEN
STRENGTHENING TUE NIGHT AND WED. WITH WEAK NORTHERLY FLOW OVER THE
WATERS AND SLIGHT RH INCREASES...THERE WILL BE BETTER CHANCES FOR
FOG AND LOW CLOUD GROWTH. THE GFS SHOWS SLIGHT OFFSHORE FLOW
CONTINUING TUE NIGHT AND WED...SO I DID NOT HIT THE LOW OVERCAST
TO HEAVY ALONG THE COAST AT THIS TIME. THE AIR ALOFT WILL WARM UP
CONSIDERABLY ON WED AS A 500MB RIDGE AXIS MOVES OVER THE AREA. THERE
WILL BE CHANCES FOR FOG AND LOW CLOUD AT THE COAST AGAIN WED NGT
AND THU AS THE INVERSION HOLDS. THE MODELS WERE IN GOOD AGREEMENT
WITH SHIFTING THE RIDGE AXIS EAST OF THE FORECAST AREA WED NIGHT
AS SHORT-WAVE TROUGH MOVES TOWARD THE WEST COAST. THE TIMING OF
THIS WAVE LOOKED ABOUT THE SAME FROM THE GFS...GEM AND ECMWF. THE
DIFFERENCES WERE MAINLY IN PRECIP GENERATION. TREND IN THE MODEL
DATA HAS BEEN TO GO SLOWER AND DRIER. IF ANYTHING THE CONSENSUS
LOOKED TO BE FOR PRECIP TO COME-IN ON THE BACKSIDE OF THE SHORT-
WAVE TROUGH AS SURFACE NORTHERLY FLOW KICKS IN. THE PRECIP SEEMS
SHALLOW IN NATURE WITH LIGHT MISTY RAIN A GOOD BET ALONG THE COAST
LATE IN THE DAY THU INTO THU NIGHT. OVERALL THIS SYSTEM WILL BRING
AN INCREASE IN MOISTURE...BUT NOT MUCH IN THE WAY OF RAIN. THE
SURFACE FRONT...IF ONE IS LEFT...MAY NOT MOVE ONTO THE NORTH COAST
TIL EARLY FRIDAY MORNING.

&&

LONG TERM...(FRI THRU TUE)...A WEAK FRONTAL SYSTEM PROGGED TO
AFFECT THE AREA ON FRIDAY WILL MOVE OUT BY SATURDAY WITH HIGH
PRESSURE BUILDING OVER THE WEST COAST. DISCREPANCIES STILL EXIST
ON THE PLACEMENT AND STRENGTH OF THE FRONT. THE MODELS HINT AT
ANOTHER POSSIBLE FRONTAL SYSTEM RIDING OVER THE TOP OF THE RIDGE
ON SUNDAY...HOWEVER...CONFIDENCE IN THIS SOLUTION IS LOW AT THIS
TIME. HAVE LOWERED POPS FURTHER IN THE LONG TERM TO ACCOUNT FOR
THE TREND FOR HIGH PRESSURE TO CONTINUE TO BUILD OVER NORTHWEST
CALIFORNIA INTO NEXT WEEK...AS A REX BLOCK LOOKS TO TAKE HOLD.
TEMPERATURES WILL GRADUALLY INCREASE THROUGH THE LONG TERM WITH
HIGHER HEIGHTS OVERHEAD. STP

&&

.AVIATION...VFR CONDITIONS AND LIGHT WINDS TO LIGHT AND VARIABLE
WINDS ARE OCCURRING AT KCEC, KACV AND KUKI THIS AFTERNOON AND WILL
CONTINUE THROUGH THIS EVENING. THE WINDS WILL BECOME LIGHT AND
VARIABLE TO CALM OVERNIGHT WITH MOSTLY CLEAR SKIES AND VFR
CONDITIONS AT KCEC, KACV AND KUKI.

&&

.MARINE...A HIGH PRESSURE RIDGE OFFSHORE AND A COASTAL LOW PRESSURE
TROUGH INCREASED THE PRESSURE GRADIENT AND THE WINDS AND SEAS ACROSS
THE WATERS. HOWEVER THE PRESSURE GRADIENT WILL CONTINUE TO RELAX
TONIGHT AND TUESDAY AND THE WINDS AND SHORT PERIOD SEAS WILL
DECREASE. THE NEAR SHORE WATERS WILL REMAIN FAIRLY LOW THROUGH THE
WEEK. THE WINDS AND SEAS WILL INCREASE THURSDAY AND FRIDAY AS A LOW
PRESSURE TROUGH MOVES ACROSS THE AREA.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...CA...NONE.

NORTHWEST CALIFORNIA COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL
3 AM PST TUESDAY PZZ470-475.

&&

$$

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