Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 281050
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
350 AM PDT THU MAY 28 2015

.SYNOPSIS...DRY AND WARMER WEATHER WILL PREVAIL ACROSS THE
INTERIOR THROUGH SATURDAY AS A HIGH PRESSURE RIDGE BUILDS ACROSS
THE AREA. SUNDAY AN UPPER LEVEL TROUGH WILL BRING COOLER
TEMPERATURES INLAND AND SOME LIGHT SHOWERS OR THUNDERSTORMS ARE
POSSIBLE.

&&

.DISCUSSION...THE RIDGE REMAINS IN PLACE OVER THE WEST COAST
TODAY. A WEAK BOUNDARY RIDING OVER THE TOP OF THE RIDGE AND IS
BRINGING SOME HIGH CLOUDS TO THE AREA. IT MAY ALSO BE LIFTING THE
MARINE LAYER A BIT...VERY LITTLE FOG HAS BEEN REPORTED THIS
MORNING. OTHER CONDITIONS WILL BE VERY SIMILAR TO YESTERDAY WITH
WARM TEMPERATURES INLAND AND COOL AND CLOUDY CONDITIONS AT THE
IMMEDIATE COAST. THE COAST MAY SEE A FEW BREAKS IN THE CLOUDS IN
THE AFTERNOON...BUT IN GENERAL SKIES WILL REMAIN CLOUDY AT THE
COAST. DESPITE THE WEAK BOUNDARY...WITH THE RIDGE BUILDING THERE
LOOKS TO BE VERY LITTLE POTENTIAL FOR SHOWERS OVER THE TRINITY
ALPS SO HAVE REMOVED THEM FROM THE FORECAST FOR THIS AFTERNOON.
TONIGHT THE MARINE LAYER IS EXPECTED TO PERSIST AND WILL BE
SIMILAR TO THIS MORNING.

FRIDAY A WEAK SHORTWAVE TRIES TO MOVE OVER THE RIDGE...HOWEVER
THERE DOES NOT APPEAR TO BE ENOUGH INSTABILITY AND MOISTURE FOR
ANY THUNDERSTORMS IN TRINITY COUNTY...ALTHOUGH THEY WILL LIKELY BE
CLOSE BY IN SISKIYOU COUNTY. HAVE LEFT A FEW SHOWERS OVER
NORTHERN TRINITY COUNTY. SATURDAY THE RIDGE REMAINS IN PLACE AND
THE INTERIOR LOOKS TO REMAIN MAINLY DRY AND AGAIN THUNDERSTORMS
WILL BE TO THE NORTH OF THE AREA. A SLIGHT SHIFT IN THE MODELS
EITHER DAY AND THERE COULD BE SOME THUNDERSTORMS IN TRINITY
COUNTY. AT THE COAST THE MARINE LAYER MAY SHRINK A BIT..BUT THE
IMMEDIATE COAST WILL LIKELY REMAIN CLOUDY.

SUNDAY A STRONGER SHORTWAVE LOOKS TO DO A BETTER JOB OF BREAKING
DOWN THE RIDGE BRINGING SHOWERS AND THUNDERSTORMS TO THE AREA IN
THE AFTERNOON. THE ECMWF AND GFS ARE IN DECENT AGREEMENT ON THIS
SYSTEM MOVING IN DURING THE AFTERNOON ON SUNDAY. CLOUD COVER LOOKS
TO BE FAIRLY EXTENSIVE SO THERE MAY NOT BE TOO MUCH DAYTIME
HEATING OVER THE INLAND AREAS. THIS WILL LIMIT THE THUNDERSTORM
POTENTIAL...BUT STILL THERE LOOKS TO BE ENOUGH MU CAPE AND
FORCING TO BRING THE POTENTIAL FOR THUNDERSTORMS ON SUNDAY. THIS
WILL NEED TO WATCHED AS IT GETS CLOSER. AT THE COAST THIS MAY MIX
OUT THE CLOUDS A BIT AND THERE MAY BE SOME MORE
CLEARING...ALTHOUGH CONFIDENCE IS LOW ON THIS. MONDAY THERE MAY BE
SOME LINGERING SHOWERS AROUND AS THE WAVE PULLS OFF TO THE EAST.

TUESDAY AND WEDNESDAY THE RIDGE OF HIGH PRESSURE STARTS TO BUILD
BACK INTO THE AREA BRINGING A RETURN OF WARM INLAND TEMPERATURES
AND MAINLY DRY CONDITIONS. MKK

&&

.AVIATION...IFR TO MVFR CONDITIONS DUE TO STRATUS WILL CONTINUE AT
THE COAST THROUGH THE DAY. THERE MAY BE SLIGHT IMPROVEMENT AROUND
MID DAY...HOWEVER WITH THE FLOW REMAINING ONSHORE AND NOTHING TO
DISRUPT THE MARINE INVERSION EXPECT STRATUS TO ADVECT BACK ONSHORE
DURING THE AFTERNOON AND SPREAD INTO THE ADJACENT COASTAL RIVER
VALLEYS BY MID EVENING. THE LAYER SHOULD COMPRESS SLIGHTLY TONIGHT
WHICH WILL RESULT IN LESS INLAND INTRUSION AND A FASTER DISSIPATION
RATE IN THE NORTH COAST RIVER VALLEYS ON FRIDAY. STRATUS IS NOT
EXPECTED TO MAKE IT INTO KUKI THIS MORNING OR TOMORROW MORNING.

&&

.MARINE...NO MAJOR CHANGES TO THE PREVIOUS FORECAST. THE SMALL
CRAFT ADVISORY FOR SHORT PERIOD SEAS OF 6 FT AT 7 SECONDS OR LESS
HAS BEEN EXTENDED THROUGH LATE FRIDAY NIGHT IN THE OFFSHORE WATERS
SOUTH OF CAPE MENDO...PZZ475. GRANTED IT IS MARGINAL...BUT
SATISFIES OUR CRITERIA BASED ON WAVE STEEPNESS. THE NORTHERLY
WINDS DRIVING THE SHORT PERIOD SEAS WILL SUBSIDE OVER THE WEEKEND
AS A WEAK SURFACE LOW BUSTS UP THE PRESSURE GRADIENT. THERE HAVE
BEEN A COUPLE OF LONGER PERIOD WAVE GROUPS IN THE SPECTRUM AS
WELL. ONE FROM THE SW AROUND 2-3 FT IN THE 12-22 SECOND BANDS AND
ANOTHER FROM THE WNW AROUND 3-4 FT IN THE 10-16 BANDS. THESE
LONGER PERIOD GROUPS WILL PERSIST INTO FRIDAY THEN FALL OFF OVER
THE WEEKEND.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY UNTIL 3 AM PDT SATURDAY FOR PZZ475.

&&

$$

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