Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 231201
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
501 AM PDT SAT MAY 23 2015

.SYNOPSIS...DRIER WEATHER CONDITIONS WITH LESS CLOUD COVER AND
SHOWER ACTIVITY IN THE INTERIOR WILL DEVELOP THIS WEEKEND AS A
RIDGE OFFSHORE BUILDS CLOSER TO THE COAST. COASTAL AREAS WILL
CONTINUE TO SEE MOSTLY CLOUDY SKIES WITH PARTIAL CLEARING IN
THE AFTERNOONS. ANOTHER TROUGH WILL BRING A CHANCE OF SHOWERS AND
THUNDERSTORMS TO THE INTERIOR ON MONDAY.

&&

.DISCUSSION...EARLY MORNING SATELLITE IMAGERY SHOWED ABUNDANT LOW
CLOUDS OVER MOST OF THE AREA. THE LOW CLOUDS WILL SCOUR OUT WITH
DAYTIME HEATING AND MIXING OVER THE INTERIOR AND ALONG THE MENDOCINO
COAST. THE BRISK ONSHORE FLOW WILL MAINTAIN CLOUD COVER THROUGH
THE DAY ALONG THE NORTH COAST...THOUGH NORTHERLY FLOW OFF CAPE
BLANCO WILL CREATE A CLEAR SLOT THAT WILL SPREAD SOUTHWARD TO PT
ST GEORGE THIS AFTERNOON AND EVENING. NAM12 X-SECTIONS INDICATE
COOL/DAMP AIR BANKING UP OVER THE COASTAL HILLS THROUGH THE DAY
AROUND HUMBOLDT BAY. SO ANY CLEARING THAT DEVELOPS TODAY AROUND
EUREKA OR OVER THE EEL DELTA WILL BE SHORT-LIVED.

A MID LEVEL VORT MAX DROPPING SOUTHWARD ALONG THE OREGON COAST
MAY TRIGGER A FEW SHOWERS OVER THE YOLLA BOLLYS AND HIGHER
ELEVATIONS OF EASTERN MENDOCINO COUNTY TODAY. PROFILES ARE NOT
SHOWING VERY MUCH MOISTURE WITH THIS VORT MAX. THE CAPE IS SHALLOW
WITH LAYERS OF STABILITY THAT WILL INHIBIT DEEP CUMULUS CLOUD
GROWTH. THUS EXPECT JUST A FEW WEAK SHOWERS. PWATS START TO
INCREASE SUNDAY AFTERNOON AS ANOTHER SHORT WAVE BEGINS TO APPROACH
THE PAC NW COAST. MODEL SOUNDINGS CONTINUE TO SHOW A STABLE LAYER
WHICH WILL PREVENT TALL CONVECTION ON SUNDAY. THE CAPE AND LIFTED
INDICES ARE MORE IMPRESSIVE ON SUNDAY...HOWEVER THERE WILL BE TOO
MUCH MID LEVEL CAPPING FOR ANYTHING MORE THAN A FEW LATE DAY
SHOWERS OVER THE TRINITY MOUNTAINS AND YOLLA BOLLYS.

ON MONDAY...MODEL BASED SOUNDINGS CONTINUE TO SHOW HIGHER CAPE
AND PWATS WITH MUCH LESS MID LAYER STABILITY. WE SHOULD SEE
SHOWERS SPROUTING UP OVER THE MOUNTAINS OF TRINITY COUNTY AND
YOLLA BOLLYS WITH DIURNAL HEATING. PARAMETERS FOR STORMS ARE
FAVORABLE AND WILL MAINTAIN ISOLATED TSTMS IN THE FORECAST.
TUESDAY LOOKS FAVORABLE AS WELL...THOUGH THE WESTERLY FLOW ALOFT
WILL KEEP STORMS MOSTLY AROUND THE PERIPHERY OF TRINITY COUNTY.

RIDGING OVER THE AREA ON WED MAY INHIBIT CONVECTION AND SHOWER
DEVELOPMENT. THE MODELS HAVE NOT BEEN VERY CONSISTENT SO WILL NOT
MAKE ANY CHANGES TO THE FORECAST AT THIS TIME. THE GFS DOES SHOW
CONVECTIVE PARAMETERS FAVORABLE FOR ISOLATED CONVECTION OVER THE
HIGHER TERRAIN ON THU AND FRI AS A COUPLE OF SHORT WAVES IN SW
FLOW ALOFT MOVE TOWARD THE AREA. SW FLOW IS TYPICALLY DRY AND NOT
VERY FAVORABLE FOR STORMS IN OUR AREA. IT IS STILL 5 TO 7 DAYS OUT
WITH PLENTY OF TIME TO ADD TSTMS TO THE FORECAST IF THE MODELS
TREND WETTER OR IF ONE OF THESE WAVES DEVELOP INTO A CLOSED LOW.
OVERALL WARMER AND DRIER CONDITIONS WILL BE THE RULE NEXT WEEK.

&&

.AVIATION...PERSISTENT MARINE LAYER WILL MAINTAIN MVFR CONDITIONS
WITH BRIEF PERIODS OF IFR MAINLY DUE TO LOWER CIGS. NOT EXPECTING
MUCH RELIEF IN TERMS OF MARINE CLOUDS OVER THE NEXT TAF CYCLE EXCEPT
FOR SOME VERY BRIEF BREAKS LATE THIS AFTERNOON.  THE INTERIOR AIR
TERMINALS WILL BE REMAIN MAINLY VFR EXCEPT FOR SOME EARLY MORNING
FOG AND LOW CLOUDS.

&&

.MARINE...WINDS AND SEAS WILL RISE A BIT DUE TO A SLIGHT INCREASE IN
NORTHERLIES. SEAS ARE A MIXTURE OF LOCALLY GENERATED WAVES FROM THE
10 TO 15 KT WINDS AND A 10 TO 12 SECOND NORTHWESTERLY WAVE. THE
NORTHERLY WINDS AND STEEP SEAS WILL INCREASE TODAY AND SUNDAY AS AN
OFFSHORE HIGH PRESSURE SYSTEM STRENGTHENS INCREASING THE PRESSURE
GRADIENT. ANOTHER UPPER LEVEL SYSTEM WILL DIMINISH THE WINDS BY THE
MIDDLE OF NEXT WEEK.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 11 PM PDT
     TUESDAY FOR PZZ470.

     SMALL CRAFT ADVISORY UNTIL 11 PM PDT SUNDAY FOR PZZ455.

     SMALL CRAFT ADVISORY UNTIL 11 PM PDT TUESDAY FOR PZZ475.

&&

$$

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