Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 282257
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
357 PM PDT THU APR 28 2016

.SYNOPSIS...A DRY COLD FRONT WILL BRING A SLIGHT PUSH OF LOW
CLOUDS FRIDAY MORNING. BRISK NORTHERLY WINDS WILL FOLLOW LATER ON
FRIDAY WITH BREEZY CONDITIONS AT THE COAST EXPECTED INTO SATURDAY.
AN OFFSHORE WIND FLOW WILL BRING WARMER WEATHER ON SUNDAY.

&&

.DISCUSSION...SATELLITE IMAGERY SHOWED A DECAYING COLD FRONT WEST
OF WASHINGTON AND OREGON OVER THE OFFSHORE WATERS THIS AFTERNOON.
THE MID LEVEL TROUGH WEST OF BRITISH COLUMBIA WILL PUSH THE FRONT
SOUTHWARD TOWARD THE FAR NW CAL COAST FRIDAY MORNING. STRONG
SURFACE RIDGING WILL LIKELY ERODE THE SURFACE BOUNDARY BEFORE IT
REACHES THE NORTH COAST ON FRIDAY. ANY RAIN FROM THE FRONT WILL
LIKELY STAY NORTH OF THE FORECAST AREA AS THE 500MB SHORT-WAVE
SWOOPS DOWN IN BRISK NORTHWESTERLY FLOW ALOFT IN THE AFTERNOON AND
EVENING. THERE WILL BE AN INCREASE IN LOW LEVEL CLOUDS MAINLY OUT
TOWARD THE COAST AND INTO THE NORTH COAST RIVER VALLEYS. THE
BRISK NORTHERLY FLOW SHOULD MIX OUT THE COASTAL LOW CLOUDS FRIDAY
NIGHT AS SURFACE HIGH PRESSURE SPRINGS BACK UP OFFSHORE. RIDGE
ALOFT AND AT THE SURFACE WILL CONTINUE TO BUILD ON SATURDAY. WARMING
IN THE INTERIOR AND AT THE COAST IS EXPECTED...HOWEVER BRISK
NORTHERLY WINDS AT THE COAST WILL PROBABLY MAKE FOR A LESS THAN
IDEAL DAY TO HEAD TO THE BEACHES. MORE WARMING IS EXPECTED ON
SUNDAY AS AN OFFSHORE FLOW DEVELOPS AND THE THERMAL TROUGH PUSHES
OFFSHORE OVER THE COASTAL WATERS. THIS WILL BE THE WARMEST DAY
BOTH AT THE COAST AND ACROSS THE INTERIOR. THERE IS STILL SOME
UNCERTAINTY ON HOW WARM IT WILL GET ON SUNDAY. IT WILL DEPEND ON
HOW FAST THE SEA BREEZES DEVELOP. CURRENT INDICATIONS ARE FOR
WINDS TO REMAIN LIGHT WESTERLY ON THE AFTERNOON AND EXPECT HIGH
TEMPS TO APPROACH 70F OR EXCEED 70F BY A FEW DEGREES.

THE RIDGE ALOFT WILL BEGIN TO BREAK DOWN AND SHIFT EASTWARD ON
MONDAY AS A DISTINCT ONSHORE FLOW PATTERN EMERGES. THE COAST WILL
LIKELY SEE A RETURN OF STRATUS AND PERHAPS FOG MON INTO TUE. THE
TIMING IS STILL NOT CERTAIN THOUGH. BOTH THE GFS AND ECMWF SHOW A
SPLITTING UPPER TROUGH APPROACHING BY TUE. THIS TROUGH WILL BRING
A COOLING TREND ACROSS THE INTERIOR NEXT WEEK. BOTH MODELS WERE IN
GENERALLY GOOD AGREEMENT BUT DIFFERED ON THE RATE OF EASTWARD
PROGRESSION AND EXACTLY WHERE AND WHEN THE CUT-OFF LOW WILL FORM.
THE LATEST GFS AND ECMWF HAVE TRENDED A BIT SLOWER AND FARTHER
WEST AND SOUTH WITH THE LOCATION OF THE CUT-OFF. CONTINUED TO
LEAN TOWARD THE SLOWER ECMWF AND KEEP A BROAD BRUSH AND VAGUE
SLIGHT CHANCE OR CHANCE OF SHOWERS WED INTO THU. THUNDERSTORMS
WILL BE A DISTINCT POSSIBILITY...HOWEVER THE DETAILS REMAIN VERY
ELUSIVE AT THIS POINT WITH TOO MUCH VARIABILITY IN THE DATA. THE
ECMWF DOES SHOW WRAP AROUND EASTERLY FLOW DEVELOPING ON THU AS
SHORT-WAVE ENERGY PIN-WHEELS WESTWARD INTO NW CA. THUS FEEL THIS
WILL BE THE BEST DAY FOR TSTMS.

&&

.AVIATION...VFR CONDITIONS PREVAILED ACROSS MOST OF NORTHERN
CALIFORNIA AS OF LATE THIS AFTERNOON WITH THE EXCEPTION OF HUMBOLDT
BAY WHERE MVFR CEILINGS BEGAN TO IMPACT KACV. TYPICALLY ONCE THESE
CEILINGS START TO DEVELOP THEY STAY. THERE COULD BE SOME
FLUCTUATIONS EARLY THIS EVENING OTHERWISE EXPECT MFR TO STICK AROUND
HUMBOLDT BAY THROUGH THE NIGHT. THIS SHOULD EVENTUALLY SPREAD TO TO
KCEC AND OTHER PARTS OF THE COAST WITH CEILINGS REACHING IFR EARLY
THURSDAY MORNING. EXPECT CONDITIONS TO IMPROVE BY LATER THURSDAY
MORNING. KML

&&

.MARINE...STRONG NORTH WINDS TONIGHT WILL DECREASE ON FRIDAY AS A
PASSING SHORTWAVE CAUSES THE PRESSURE GRADIENT TO RELAX. THE CURRENT
GALE WARNING AND SMALL CRAFT ADVISORIES LOOK ON TRACK FOR TONIGHT
BUT I HAD TO MAKE SOME ADJUSTMENTS TO REFLECT THE DECREASING WINDS
TOMORROW. ADVISORIES SHOULD CONTINUE SOUTH OF CAPE MENDOCINO AS
STRONGER WINDS ARE EXPECTED TO PERSIST BUT THE ADVISORIES NORTH OF
THE CAPE ARE SET TO EXPIRE BY MID-MORNING ON FRIDAY. THIS WILL
SIGNAL THE BEGINNING OF A BRIEF WINDOW FOR LOWER WINDS(15 TO 20 KT)
AND SEAS FRIDAY BEFORE CONDITIONS INCREASE AGAIN ON SATURDAY.
OTHERWISE STEEP WAVES WILL BUILD IN RESPONSE TO THE INCREASING WINDS
WHILE A MIDDLE PERIOD SWELL WILL GRADUALLY DIMINISH THROUGH THE
WEEKEND. THERE WILL BE A BETTER WINDOW FOR SETTLING CONDITIONS
BEGINNING LATE THIS WEEKEND THROUGH EARLY NEXT WEEK. KML

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
 SMALL CRAFT ADVISORY UNTIL 9AM PDT FRI FOR PZZ450-470.
 SMALL CRAFT ADVISORY UNTIL 3AM PDT SAT FOR PZZ455.
 GALE WARNING UNTIL 3AM PDT FRI FOR PZZ475.

&&

$$

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