Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 292247
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
347 PM PDT FRI AUG 29 2014

.SYNOPSIS...AN APPROACHING DISTURBANCE FROM THE NW WILL BRING A COOL
DOWN TO NW CALIFORNIA FOR SATURDAY AND SATURDAY NIGHT. THIS SYSTEM
WILL ACT TO DEEPEN THE MARINE LAYER WHICH WILL DRIVE CLOUDS FARTHER
UP THE RIVER VALLEYS TONIGHT AND TOMORROW NIGHT. BY SUNDAY WEAK HIGH
PRESSURE WILL BEGIN TO BUILD OVER THE REGION...BRINGING MORE
SEASONABLE CONDITIONS.

&&

.DISCUSSION...MODELS REMAIN IN GOOD AGREEMENT WITH AN UPPER TROUGH
MOVING INTO THE PACIFIC NW THIS WEEKEND. NW CALIFORNIA WILL GET
CLIPPED BY THIS TROUGH CAUSING A COOL DOWN IN MAX AND MIN TEMPS FOR
SATURDAY. NO RAIN IS EXPECTED TO ACCOMPANY THIS SYSTEM, WITH THE
EXCEPTION OF LOCALIZED DRIZZLE IN SOME COASTAL AREAS. FOR THE
FORECAST, ADJUSTED THE TEMPS DOWN FOR SATURDAY AS MODELS ARE SHOWING
A DECENT AMOUNT OF COOL AIR FILTERING INTO THE AREA.
MODELS CONTINUE TO ALLOW THE REMNANTS OF TROPICAL SYSTEM MARIE DRIFT
TO THE NW. HOWEVER, SOME UPPER LEVEL MOISTURE HAS BEEN ENTRAINED
INTO THE EXTRATOPICAL FLOW WHICH HAS BEEN STREAMING OVER AREAS FROM
MENDOCINO COUNTY SOUTHWARD MUCH OF TODAY. THIS WILL LIKELY CONTINUE
THROUGH SATURDAY WHEN THE REMNANTS OF MARIE BECOME DISCONNECTED FROM
THE OVERALL FLOW DUE TO A BUILDING RIDGE OVER CALIFORNIA ON SUNDAY.
THIS RIDGE WILL BRING A RETURN TO MORE SEASONAL TEMPS AND HUMIDITY
THROUGH ABOUT TUESDAY.
BY MIDWEEK ANOTHER UPPER TROUGH WILL DIG TOWARD THE PAC NW. MODELS
ARE SHOWING THAT THIS TROUGH WILL PICK UP WHATEVER IS LEFT OF MARIE
AND SHIFT IT TOWARD THE COAST. MODELS ARE NOT INDICATING ANY PRECIP
WITH THIS TROUGH LATE IN THE WEEK. HOWEVER, THE REMNANTS OF A
TROPICAL SYSTEM CAN OFTEN BRING ABUNDANT MOISTURE TO AN UNSTABLE
TROUGH AS IT IS SWEPT UP INTO THE EXTRA-TROPICAL FLOW. UNCERTAINTY
IS HIGH WITH ANY PRECIP OR CONVECTION DEVELOPING LATE IN THE WEEK,
BUT IT WILL BE SOMETHING TO WATCH. UNCERTAINTY ENCOMPASSES POTENTIAL
OCCURANCE, TIMING, AND LOCATION. AS SUCH, HAVE LEFT POPS BELOW ANY
MENTIONABLE AMOUNTS FOR NOW.
OTHERWISE, CONTINUE TO EXPECT FAIR CONDITIONS ACROSS THE INTERIOR
WITH MORE LOW CLOUDS AND FOG AT THE COAST. BFG

&&

.AVIATION...MOST OF THE COASTAL STRATUS LIFTED TODAY AT LEAST FOR
BRIEF PERIODS WHILE HIGH CLOUD COVER FILTERED ACROSS MENDOCINO
COUNTY. THE OFFSHORE CLOUD DECK IS NOT AS EXPANSIVE AS IT WAS
YESTERDAY BUT STILL ANTICIPATE IFR TO LIFR CEILINGS AND
VISIBILITIES TO RETURN TO MOST OF THE COAST AGAIN TONIGHT. AN
APPROACHING TROUGH MAY ASSIST IN DEEPENING THE MARINE LAYER
OVERNIGHT, HOWEVER, WE DON`T EXPECT MAJOR MODIFICATIONS TO THE
AIRMASS WITHIN THE TAF PERIOD. AS RESULT, TONIGHT SHOULD BE
SIMILAR TO LAST NIGHT FOR COASTAL AIRFIELDS. VFR WILL PREVAIL
ACROSS INTERIOR AREAS WITH ONLY HIGH CLOUD COVER SHIFTING OVER
NORTHWEST CALIFORNIA. KML

&&

.MARINE...THE 19Z ASCAT PASS SHOWED LIGHT NORTHERLY WINDS NORTH OF
CAPE MENDOCINO AND 20 KT WINDS PERSISTING SOUTH OF THE CAPE. NEW
MODEL SOLUTIONS SHOW THAT WINDS ACROSS THE NORTHERN WATERS WILL
LIKELY REMAIN LIGHT EARLY THIS WEEKEND AND THUS EXPIRED THE SMALL
CRAFT ADVISORY FOR MARINE ZONE 470. THE ADVISORY FOR THE SOUTHERN
OUTER WATERS (ZONE 475) HAS BEEN EXTENDED THROUGH EARLY NEXT WEEK
WITH HIGHER CONFIDENCE AND CONSISTENCY IN THE MODELS SHOWING SMALL
CRAFT CONDITIONS THROUGH THE WEEKEND. STRONG RIDGING OFF THE WEST
COAST WILL BRING NEAR GALE CONDITIONS ACROSS THE COASTAL WATERS
THROUGH THE MIDDLE OF NEXT WEEK. WINDS ACROSS THE NORTHERN WATERS
WILL INCREASE LATE IN THE WEEKEND AND WILL LIKELY NEED A SMALL
CRAFT ADVISORY BY EARLY NEXT WEEK. KML

&&

.FIRE WEATHER...THE MAIN FIRE WEATHER CONCERN WILL BE FOR GUSTY
WINDS ALONG AREA RIDGE THROUGH SATURDAY NIGHT. AN UPPER TROUGH
CROSSING THE AREA EARLY THIS WEEKEND WILL BRING THE POSSIBILITY OF
GUSTS AS HIGH AS 25 TO 30 MPH, ESPECIALLY ALONG COASTAL RIDGES OF
DEL NORTE AND HUMBOLDT COUNTIES. OTHERWISE, RH VALUES WILL RECOVER
WELL THROUGH SUNDAY MORNING AS THIS TROUGH DEEPENS THE MARINE LAYER
AND DRIVES MOISTURE TOWARD THE INTERIOR. BFG

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 3 PM PDT TUESDAY PZZ475.

&&

$$

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