Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 021233
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
433 AM PST MON MAR 2 2015

.SYNOPSIS...A WEAK SYSTEM WILL BRING A FEW SHOWERS TO NORTHWEST
CALIFORNIA TODAY. UPPER LEVEL RIDGING WILL BEGIN TO DEVELOP OVER
THE WEST COAST ON TUESDAY AND THEN PERSIST INTO THIS COMING
WEEKEND. THE DEVELOPING RIDGE WILL RESULT IN DRY CONDITIONS AND
A GRADUAL WARMING TREND THROUGH THE WEEK.

&&

.DISCUSSION...AN UPPER LEVEL SHORTWAVE IS QUICKLY PASSING THROUGH
NORTHWEST CALIFORNIA THIS MORNING. SHOWERS HAVE INCREASED IN NUMBER
OVER THE COASTAL WATERS AND SOME HAVE MOVED ONSHORE NEAR CAPE
MENDOCINO. THIS TREND SHOULD CONTINUE THROUGH THE MORNING HOURS
UNTIL THE SHORTWAVE PASSES SOUTH OF THE AREA AND WEAK CONVERGENT
FLOW OVER THE MOUNTAINS OF EASTERN MENDOCINO AND SOUTHERN TRINITY
COUNTIES ALLOWS SOME ADDITIONAL SHOWERS TO FORM LATER THIS MORNING
AND AFTERNOON. INSTABILITY NOW APPEARS TO BE QUITE MINIMAL SO
THUNDER HAS BEEN REMOVED FROM THE FORECAST FOR THIS AFTERNOON.

A DRYING TREND WILL RAPIDLY DEVELOP THIS EVENING AS SLIGHTLY DRIER
AIR BEGINS TO MOVE OVER NORTHWEST CALIFORNIA BEHIND THE DEPARTING
UPPER LEVEL SHORTWAVE. HOWEVER...MODEL GUIDANCE INDICATES HIGH
BOUNDARY LAYER MOISTURE MAY ALLOW A SIGNIFICANT NUMBER OF LOW
CLOUDS TO REMAIN ACROSS THE REGION...PARTICULARLY IN THE HUMBOLDT
BAY AREA AND MENDOCINO COUNTY. THIS CLOUD COVER MAY ACTUALLY
DECREASE IN COVERAGE OVERNIGHT ALLOWING TEMPERATURES TO EVENTUALLY
FALL POSSIBLY TO FROST/FREEZE CRITERIA IN THE ACTIVE GROWING
SEASON ZONES. CONSIDERING THE HIGH UNCERTAINTY OF THE DEPARTING
CLOUD COVER HAVE OPTED TO HOLD OFF ON ANY FREEZE/FROST PRODUCTS
FOR TONIGHT.

COLD AIR WILL REMAIN IN PLACE TUESDAY NIGHT WHILE THE ATMOSPHERE
CONTINUES TO DRY. THUS THERE IS A HIGHER POSSIBILITY OF
FROSTY/FREEZING TEMPERATURES TUESDAY NIGHT INTO WEDNESDAY MORNING.
TEMPERATURES HAVE BEEN TRENDED DOWN CLOSER TO THE GFSBC GUIDANCE
WITH LOWS IN THE 20S TO LOWER 30S ACROSS THE INTERIOR VALLEYS AND
THE MIDDLE TO UPPER 30S NEAR THE COAST.

UPPER LEVEL RIDGING WILL BUILD OVER THE WEST COAST MIDWEEK INTO NEXT
WEEKEND BRINGING A GRADUALLY WARMING TREND AND DRY CONDITIONS TO
NORTHWEST CALIFORNIA. DEPENDING ON WHERE EXACTLY THE UPPER LEVEL
RIDGE SETTLES THERE MAY BE PERIODS OF MARINE LAYER CLOUDINESS BUT
CONFIDENCE IN ANY STRATUS OVER THE WATERS IMPACTING THE COAST IS
CURRENTLY LOW. /RPA


&&

.AVIATION...VFR SHOULD PREVAIL TODAY WITH SOME GUSTY WINDS ALONG
COASTAL LOCATIONS. LIGHT RAIN SHOWERS MAY PERIODICALLY LOWER CEILINGS
THROUGH THE DAY HOWEVER CHANCES ARE SLIGHT WITH MOST OF THE SHOWERS
EXPECTED TO REMAIN OFFSHORE. HIGHER CLOUD COVER ASSOCIATED WITH A
LOW PRESSURE SYSTEM WILL GRADUALLY DECREASE THROUGH THE DAY AS THE
LOW SHIFTS TO THE SOUTH. PATCHY FOG MAY DEVELOP ACROSS INTERIOR
VALLEYS LATE TONIGHT AS RIDGING BUILDS BEHIND THE PASSING LOW.
OTHERWISE VFR SHOULD PREVAIL FOR THE MAJORITY OF THE REGION LATE
TONIGHT. /KML


&&

.MARINE...A PASSING LOW PRESSURE SYSTEM WILL RAMP UP NORTHERLY WINDS
AND CAUSE STEEP SEAS TO BUILD THROUGH THIS AFTERNOON. THE GALES WERE
LEFT UNCHANGED AS THE HIGHEST WINDS, IN ADDITION TO STEEP SEAS, ARE
EXPECTED ACROSS THE OUTER WATERS WITH GUSTS NEAR 40 KT THROUGH THIS
EVENING. LARGE, STEEP SEAS WILL PROPAGATE FROM OFFSHORE TO THE INNER
WATERS THUS HAZARDOUS SEAS WARNINGS WERE ISSUED FOR BOTH OF THE NEAR
SHORE ZONES. THE NORTHERN INNER WATERS BEGAN AT 12Z THIS MORNING AS
BUOY OBSERVATIONS WERE REPORTING 10 TO 11 FT SEAS AROUND 9 SECONDS.
THE SOUTHERN INNER WATERS WILL BEGIN A LITTLE LATER THIS MORNING AS
THERE WILL BE A SLIGHT LAG IN BUILDING SEAS. OCCASIONAL GALE FORCE
GUSTS WILL BE POSSIBLE IN THE NEARSHORE WATERS TODAY ESPECIALLY NEAR
POINT SAINT GEORGE AND CAPE MENDOCINO. THERE WILL BE A POSSIBILITY
THAT A GALE MAY BE NEEDED IF THE GUSTS BECOME MORE FREQUENT,
HOWEVER, THE JET IS FORECAST TO REMAIN FARTHER OFFSHORE ALONG WITH
THE HIGHEST WINDS. THE DIFFICULT ASPECT TO THIS SITUATION IS THE
LACK OF WIND OBSERVATIONS TO VERIFY COASTAL CONDITIONS BUT EITHER
WAY IT IS LOOKING LIKE A CRUMMY DAY OUT ON THE OCEAN. WINDS AND SEAS
WILL BEGIN TO EASE TONIGHT THROUGH TUESDAY AS THE LOW PRESSURE
SYSTEM AND ASSOCIATED JET DIVE SOUTHWARD. CONDITIONS WILL SETTLE
FURTHER LATE IN THE WEEK AS BUILDING HIGH PRESSURE WEAKENS THE
PRESSURE GRADIENT. /KML


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY UNTIL 3 AM PST TUESDAY FOR PZZ450.

     HAZARDOUS SEAS WARNING UNTIL 9 PM PST THIS EVENING FOR PZZ450.

     GALE WARNING UNTIL 9 PM PST THIS EVENING FOR PZZ470-475.

     SMALL CRAFT ADVISORY UNTIL 9 PM PST THIS EVENING FOR PZZ455.

     HAZARDOUS SEAS WARNING FROM 9 AM THIS MORNING TO 9 PM PST THIS
     EVENING FOR PZZ455.

&&

$$

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