Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 032127
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
213 PM PDT TUE MAY 3 2016

.SYNOPSIS...MAINLY CLOUDY SKIES FOR THE NEXT FEW DAYS AS A
WEAK STORM SYSTEM AND ASSOCIATED COLD FRONT MOVE THROUGH THE
REGION. SCATTERED SHOWERS ARE LIKELY FOR ALL OF NORTHWEST CA
WHILE A FEW ISOLATED THUNDERSTORMS ARE POSSIBLE ACROSS INTERIOR
AREAS DURING THE AFTERNOONS AND EARLY EVENINGS THROUGH THIS
WEEKEND.


&&

.DISCUSSION...SHORT TERM (TONIGHT-FRI NIGHT) AN UPPER TROUGH
CURRENTLY DIGGING OFF THE COAST OF NORTHERN WASHINGTON AND
AN ASSOCIATED COLD FRONT STILL WELL OFF THE NORTHERN CA COAST
HAS BROUGHT PLENTY OF MID AND HIGH CLOUDS TO THE REGION TODAY.
ALSO MID AND UPPER LEVEL SOUTHERLY FLOW HAS COMBINED WITH SOME
AVAILABLE MOISTURE AND INCREASED INSTABILITY TO FORM SOME SHOWER
ACTIVITY. THE SHOWERS ARE CURRENTLY MOVING NORTHWARD OVER THE
YOLLA BOLLI MOUNTAINS AS WELL AS EASTERN DEL NORTE COUNTY. AS OF
2PM NO TSTORMS HAVE BEEN DETECTED BUT THERE IS STILL SOME CHANCES
OVER THE NEXT FEW HOURS DUE TO INCREASED SURFACE HEATING. THE
FRONT WILL MOVE SOUTHEAST OF THE NORTHERN CALIFORNIA LATER TONIGHT
BUT AS THE TROUGH MOVES CLOSER TO THE COAST IT INTENSFIES AND
ORGANIZES ALLOWING ANOTHER WAVE OF ENERGY TO SUPPLY MORE SHOWER
ACTIVITY AND ENHANCED THUNDERSTORM CHANCES WED AFTERNOON. AN
AREA OF UPPER DIVERGENCE WILL BE FOCUSED OVER NW CA TOMORROW
AFTERNOON FOR AT LEAST ONE MORE INGREDIENT TO HELP INITIATE
AND SUSTAIN CONVECTIVE ACTIVITY. AT THIS TIME DO NOT EXPECT ANY
CELLS TO REACH SEVERE CRITERIA BUT SOME HEAVIER SHOWERS ARE
POSSIBLE AND SMALL HAIL MAY ACCOMPANY ANY LIGHTNING. THE UPPER LOW
WILL REMAIN QUASI STATIONARY THROUGH EARLY THURSDAY WHILE
ADDITIONAL VORT LOBES ROTATE THROUGH THE DEFORMATION ZONE. THUS
THURSDAY MAY ALSO SEE ANOTHER ROUND AND SHOWER AND POSSIBLE TSTORM
ACTIVITY. BY FRIDAY THE LOW PRESSURE SYSTEM WILL BEGIN TO DRIFT
INTO SOUTHERN CA ALLOWING FLOW TO CHANGE FROM SOUTHERLY TO
NORTHEASTERLY OVER THE CWA. THIS WILL PUT A RATHER QUICK END TO
SHOWER AND TSTORM POTENTIAL WHILE ALLOWING SOME SUNSHINE TO
FINALLY RETURN TO MOST AREAS. JT

LONG TERM (SAT-TUE) DRY THROUGH THE WEEKEND INTO EARLY NEXT
WEEK...WITH ABOVE- NORMAL TEMPERATURES EXPECTED. THE START OF THE
LONG TERM WILL FEATURE GENERAL RIDGING OVER THE PACIFIC
NORTHWEST...WITH AN UPPER LEVEL CUTOFF LOW OVER SOUTHERN
CALIFORNIA/ARIZONA. THIS CONFIGURATION WILL FAVOR OFFSHORE FLOW
OVER THE NORTH COAST OF CALIFORNIA. OVER THE INTERIOR...ISOLATED
TO SCATTERED SHOWERS ARE EXPECTED DUE TO THE INSTABILITY
ASSOCIATED WITH THE UPPER LEVEL CUTOFF LOW. THE UPPER LEVEL CUTOFF
LOW WILL WEAKEN AND SHIFT EAST THROUGH THE WEEKEND. THE
PRECIPITATION POTENTIAL WILL LOWER AS A RESULT. WITH DRY OFFSHORE
FLOW, DO EXPECT TEMPERATURES TO GET INTO THE 60S ALONG THE COAST,
AND INTO THE LOW 80S IN THE INTERIOR. UTILIZE ECMWF AND GFS IN
UPDATING THE FORECAST PACKAGE. FORECAST CONFIDENCE IS ABOUT
AVERAGE. RL &&

.AVIATION...A FRONTAL BOUNDARY AND UPPER LOW WAS RESPONSIBLE FOR THE PLETHORA OF
VARIABLE CLOUDINESS THAT IMPACTED LOCAL AIRPORTS/AIRFIELDS ACROSS
THE REGION.

COASTAL AIRPORTS: A PERSISTED STRATUS LAYER HAD A SOMEWHAT MINOR
IMPACT AT AIRPORT TERMINALS TODAY. CIGS VARIED FROM MOSTLY MVFR TO
IFR/LIFR AROUND HUMBOLDT BAY. LIGHT DRIZZLE WAS REPORTED BY LATE
MORNING AS THE FRONT MOVED ONSHORE. THROUGH THE FORECAST CYCLE...THE
CANOPY OF CLOUDINESS WILL PERSIST (OTHER THAN A FEW BREAKS HERE AND
THERE) WITH INTERMITTENT LIGHT RAIN/OCCASIONAL SHOWERS THIS EVENING
AS LOW PRESSURE PREVAILS.

INTERIOR AIRFIELDS:
THE UPPER LEVEL LOW/TROUGH AND ASSOCIATED COLD FRONT WILL CONTINUE
TO INCREASED THE MOISTURE AND DECREASE STABILITY THROUGH THE PERIOD.
ALONG WITH OROGRAPHIC LIFTING...THE THREAT OF SHOWERS AND EVEN
ISOLATED THUNDERSTORMS ARE POSSIBLE WITH THE THREAT EVEN GREATER ON
WEDNESDAY AS THE LOW DRAWS CLOSER TO THE REGION. TA



&&

.MARINE...NORTHERLY WINDS AND SHORT PERIOD SEAS WILL INCREASE
TONIGHT AND WED. ADVISORIES HAVE BEEN ISSUED FOR THE OUTER WATERS
FOR BOTH WINDS AND SEAS. SEAS SHOULD BECOME SUFFICIENTLY STEEP
INSIDE 10NM NORTH OF THE CAPE ON WED TO WARRANT AN ADVISORY. A GALE
WARNING HAS ALSO BEEN POSTED FOR THE NORTHWESTERN FRINGES OF PZZ470
STARTING WED AFTERNOON.

NORTHERLY WINDS WILL LIKELY CONTINUE TO INCREASE THU AND FRI...WITH
GALES EXPECTED IN THE NORTHERN OUTER WATERS WHICH IS 10-60NM
OFFSHORE FROM PT ST GEORGE TO CAPE MENDO. GALE FORCE WINDS MAY ALSO
EXTEND INTO THE NORTHERN PORTION OF THE SOUTHERN OUTER WATERS WHICH
IS 10-60NM OFFSHORE FROM CAPE MENDO TO PT ARENA.

SHORT PERIOD SEAS GENERATED FROM THE STRONG NORTHERLIES OFFSHORE
WILL BE THE PRIMARY HAZARD INSIDE 10NM...THOUGH A FEW RIBBONS OF
STRONG WIND MAY DEVELOP INSIDE 10NM THU AND FRI...MAINLY AROUND PT
ST GEORGE. SEAS MAY APPROACH CRITERIA FOR A WARNING THU INTO FRI
INSIDE 10NM NORTH OF THE CAPE...HOWEVER THERE IS STILL SOME
UNCERTAINTY ON HOW LARGE SEAS WILL GET. CURRENT INDICATIONS ARE FOR
SEAS TO HIT 10-12 FT AT 9 TO 11 SECONDS WHICH IS BORDERLINE.
MENDO WATERS WILL SEE A RAMP UP IN SHORT PERIOD WAVES AS
WELL...HOWEVER CURRENT INDICATIONS ARE FOR THE HIGHEST SEAS TO
REMAIN AROUND THE CAPE. DJB


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY FROM NOON WEDNESDAY TO 11 AM PDT SATURDAY
     FOR PZZ450.

     SMALL CRAFT ADVISORY UNTIL NOON PDT WEDNESDAY FOR PZZ470.

     GALE WARNING FROM NOON WEDNESDAY TO 3 AM PDT SATURDAY FOR PZZ470.

     SMALL CRAFT ADVISORY UNTIL 6 PM PDT WEDNESDAY FOR PZZ475.

     HAZARDOUS SEAS WATCH FROM WEDNESDAY EVENING THROUGH LATE FRIDAY
     NIGHT FOR PZZ475.

&&

$$

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