Hazardous Seas Warning 23, NWS Eureka, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
240 PM PDT WED JUL 22 2009

.SYNOPSIS...STRONG HIGH PRESSURE ALOFT WILL MAINTAIN HOT AND DRY
WEATHER CONDITIONS ACROSS THE INTERIOR THROUGH THE WEEK. MOST OF
THE COAST WILL REMAIN COOL UNDER MOSTLY CLOUDY SKIES.

&&

.DISCUSSION...NEAR STEADY STATE FORECAST FOR THE NEXT SEVERAL
DAYS...WITH NO MAJOR CHANGES IN THE SYNOPTIC SCALE FLOW PATTERN
ANTICIPATED. A STRONG UPPER RIDGE WILL REMAIN ANCHORED OVER THE
DESERT SOUTHWEST...WHILE A POSITIVELY TILTED UPPER TROUGH PERSISTS
OVER THE NORTHEAST PACIFIC. A COUPLE OF PERTURBATIONS...IN THE
SOUTHWEST FLOW BETWEEN THE RIDGE AND TROUGH...WILL SKIRT OVER NW
CALIFORNIA FROM TIME TO TIME. THESE PERTURBATIONS ARE DRY AND
SHOULD ONLY GENERATE A FEW HIGH LEVEL CIRRUS...AND PERHAPS A FEW
TOWERING CUMULUS OVER THE MOUNTAINS. LOOKS LIKE WE WILL SEE
SLIGHT COOLING ON THU AND FRI AS MODIFIED MARINE AIR FILTERS INTO
THE COASTAL RIVER VALLEYS. STRATUS FORECAST HAS BEEN BASED
PRIMARILY ON PERSISTENCE. HOWEVER...SLIGHT OFFSHORE FLOW ON THU
AND FRI SHOULD BRING BETTER OPPORTUNITIES FOR CLEARING. COMPLETE
ERADICATION IS UNLIKELY AND SUSPECT LOW CLOUDS AND FOG TO RETURN
DURING THE EVENING HOURS.

SATURDAY AND BEYOND...THE GFS AND ECWMF...CONTINUE TO INDICATE
A WARM UP SAT THROUGH TUE...WITH 500MB HEIGHTS PUMPING UP TO 590+
DECAMETERS AND 850MB TEMPS OF 25-30C. WE SHOULD SEE MAX TEMPS
CLIMB TO 105-110F IN THE WARMEST INTERIOR VALLEYS. GFS DOES
INDICATE MARGINAL SURFACE-BASED INSTABILITY...BUT VERY LIMITED
MID-LAYER MOISTURE ON TUE. FOR NOW TOSSED IN A 10-15% CHANCE OF
TSTMS ON TUESDAY OVER THE HIGHER TERRAIN OF TRINITY COUNTY. DJB

&&

.AVIATION...WINDS INCREASING OVER THE COASTAL WATERS ARE ENHANCING
MIXING OF THE MARINE LAYER THIS AFTERNOON...AND BEGINNING TO ERODE
THE STRATUS LAYER TOWARD THE COAST. CONTINUED CLEARING IS LIKELY
DURING THE REMAINDER OF THE AFTERNOON...WITH CIGS SCATTERING TO VFR
FOR AT LEAST A FEW HOURS. EXPECT CONDITIONS TO DETERIORATE AGAIN
LATER THIS EVENING AS STRATUS REFORMS AND ADVECTS INLAND UNDER
ONSHORE FLOW. VFR CONDITIONS WILL PREVAIL ACROSS THE INTERIOR. CC

&&

.MARINE...MODERATE N TO NW WINDS WILL CONTINUE INTO THE WEEKEND AS
HIGH PRESSURE OVER THE EASTERN PAC INTERACTS WITH A TROUGH OF LOW
PRESSURE ALONG THE COAST. THIS WILL MAINTAIN ADVISORY LEVEL WINDS
AND SEAS OVER THE OUTER WATERS THROUGH THE WEEK. OCCASIONAL GALE
FORCE GUSTS ARE LIKELY OVER THE OUTER WATERS NORTH OF CAPE
MENDOCINO...HOWEVER NOT IN SUFFICIENT COVERAGE OR DURATION TO
WARRANT A GALE WARNING. MODELS CONTINUE TO ADVECT A LONG PERIOD
SOUTHERLY SWELL INTO THE WATERS BEGINNING FRI. LATEST MODEL RUNS
CONTINUE TO ADVERTISE 3 TO 5 FT SWELL AT 18 TO 20 SEC BEGINNING FRI
AND CONTINUING THROUGH EARLY NEXT. THIS LONG PERIOD SWELL COULD
PRODUCE 10 FT BREAKERS ALONG S FACING BEACHES SO WILL NEED TO
CONTINUE MONITORING BUOY DATA AS THIS SWELL TRAIN NEARS. CC

&&

.EKA WATCHES/WARNINGS/ADVISORIES...SMALL CRAFT ADVISORY PT ST GEORGE
TO PT ARENA OUT 10-60NM AND CAPE MENDOCINO TO PT ARENA 0-10NM.

&&

VISIT US AT HTTP://WWW.WEATHER.GOV/EUREKA