Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 281450 CCA
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
750 AM PDT FRI AUG 28 2015

.SYNOPSIS...AN UNSEASONABLY STRONG FRONT WILL RAPIDLY MOVE ACROSS
NORTHWEST CA TONIGHT...ACCOMPANIED BY RAIN AND HIGH ELEVATION
GUSTY WINDS THROUGH EARLY SATURDAY MORNING.

&&

.DISCUSSION...MAINLY HIGH CLOUDS SPREADING OVER THE REGION THIS
MORNING IN ADVANCE OF THE VERY SLOW MOVING FRONT STILL WELL OFF
THE COAST. FORECAST MODELS IN GOOD AGREEMENT IN TERMS OF THE
FRONT BECOMING SOMEWHAT STATIONARY OFF THE COAST TODAY THEN MOVING
IT THROUGH AS A COLD FRONT BETWEEN MIDNIGHT TONIGHT AND SUNRISE
SATURDAY. STILL ANTICIPATING LIGHT TO MODERATE RAIN OVER AREAS
NORTH OF HWY 299 WITH LIGHTER AMOUNTS SOUTHWARD. ONE CAVEAT IS THE
RAPID PROGRESSION OF THE FRONT...WHICH WOULD LEND CREDENCE TO
LESSER AMOUNTS OF RAIN THAN WHAT IS CURRENTLY FORECASTED.
NONETHELESS IT WOULD BE HARD TO GO AGAINST ALL THE MODEL AGREEMENT
AT THIS TIME THUS ONLY MADE VERY MINOR ADJUSTMENTS TO THE VALUES
CURRENTLY IN THE FORECAST. STILL ROUGHLY EXPECTING AT LEAST A HALF
AN INCH ACROSS RAIN PRONE AREAS OF EXTREME NW CA WITH GREATER
COLLECTIONS ALONG PREFERRED LOCATIONS. ONCE THE FRONT PASSES EARLY
SATURDAY SOME SHOWER ACTIVITY WILL LINGER THROUGH THE
AFTERNOON...ESPECIALLY OVER DEL NORTE COUNTY AND OVER THE HIGHER
TERRAIN. THE GFS AND ECMWF SHOW ANOTHER IMPULSE MOVING TOWARD THE
NORTH COAST ON SUNDAY. HOWEVER THE LATEST MODELS DAMPEN-OUT THE
SURFACE REFLECTION OF THIS WAVE SIGNIFICANTLY. FOR NOW WILL MAINTAIN
A CHANCE OR SLIGHT OF SHOWERS MAINLY NORTH OF THE CAPE...CONSIDERING
THE NAM12 DOES SHOW MORE PRECIP SPROUTING UP WITH THE ONSHORE FLOW.
FROM MONDAY THROUGH THURSDAY...A BROAD UPPER LEVEL TROUGH WILL
REMAIN OVER THE WEST COAST THROUGH THE PERIOD. MAIN AFFECT FOR NW
CALIFORNIA WILL BE BELOW NORMAL TEMPERATURES IN THE INTERIOR WITH
SLIGHTLY ABOVE NORMAL TEMPERATURES FOR COASTAL AREAS. SEVERAL WEAK
PERTURBATIONS EMBEDDED WITHIN THE LARGER SCALE TROUGH WILL MOVE INTO
THE PAC NW FROM TIME TO TIME. NONE OF THESE SHORTER WAVE LENGTH
FEATURES APPEAR TO BE STRONG ENOUGH TO GENERATE SIGNIFICANT PRECIP.
THE TAIL END OF THESE WAVES MAY GENERATE SOME LIGHT SHOWERS NEAR THE
ORCA BORDER. FOR NOW WILL MAINTAIN NEAR CLIMO PRECIP CHANCES FOR
MOST OF THE FORECAST AREA AND SLIGHTLY ABOVE NORMAL CHANCES NEAR THE
ORCA BORDER.


&&

.AVIATION...MID AND HIGH LEVEL CLOUD COVER WILL CONTINUE TO INCREASE
TODAY.  VFR CIGS WILL LIKELY PERSIST THROUGH THE DAY...BUT THIS WILL
CHANGE TONIGHT DURING THE OVERNIGHT HOURS AS A FRONTAL SYSTEM
REACHES THE COAST...LIKELY RESULTING IN A BRIEF PERIOD OF IFR CIGS
AND MODERATE RAINFALL PARTICULARLY AT CEC. CONDITIONS AT UKI ARE
MORE UNCERTAIN...BUT A BRIEF PERIOD OF LIGHT RAIN AND LOWERING CIGS
WILL BE POSSIBLE TONIGHT THERE AS WELL.

&&

.MARINE...LIGHT WINDS CONTINUE THROUGHOUT THE WATERS THIS MORNING AS
AN EARLY SEASON FRONTAL SYSTEM GRADUALLY APPROACHES FROM THE WEST.
SEAS CONTINUE TO BE MIXED BUT GENERALLY MILD MANNERED...WITH
SIGNIFICANT WAVE HEIGHTS OF 3 TO 5 FEET AND TWO DISTINCT WAVE GROUPS
CENTERED AROUND 8 AND 15 SECONDS...RESPECTIVELY. AS THE FRONTAL
SYSTEM APPROACHES TOMORROW...SOUTH SOUTHWESTERLY WINDS WILL BEGIN TO
INCREASE...LIKELY INTO THE FRESH RANGE ALTHOUGH THERE IS A BIT OF
UNCERTAINTY REGARDING JUST HOW STRONG THE WINDS WILL GET. THIS FRONT
WILL ALSO LIKELY RESULT IN A RELATIVELY BRIEF PERIOD OF MODERATE AND
PERHAPS PERIODICALLY HEAVY RAINFALL TONIGHT...FOLLOWED BY SOME
SHOWERY ACTIVITY TOMORROW MORNING. PEAK WIND SPEEDS WILL LIKELY BE
REACHED DURING THE OVERNIGHT HOURS TONIGHT ACROSS THE NORTHERN OUTER
WATERS AND BEGIN TO DECREASE BY TOMORROW EVENING. THIS SHOULD ALLOW
STEEPER SHORT PERIOD SEAS TO SETTLE A BIT...BUT MULTIPLE SWELL
GROUPS WILL ALSO BE PRESENT IN THE WATERS. THE FIRST OF WHICH THAT
MAY BE MODERATELY SIGNIFICANT WILL BE A WESTERLY LONG PERIOD SWELL
SET TO BUILD INTO THE WATERS OVERNIGHT TOMORROW AND INTO THE DAY
SUNDAY. WHILE NOT OVERLY LARGE...THIS WILL LIKELY BUILD TO AROUND 4
FEET AT 17 SECONDS SUNDAY AFTERNOON...AT A TIME WHEN WINDS AND SHORT
PERIOD SEAS SHOULD BE ON THE DECLINE. WHILE NOT A HUGE CONCERN FOR
BOATERS...THIS COULD PRESENT A MODERATE SNEAKER WAVE THREAT FOR AREA
BEACHES DEPENDING ON HOW QUICKLY WINDS SUBSIDE ON SUNDAY. SUNDAY
NIGHT...AN ADDITIONAL NORTHWESTERLY SWELL WILL BUILD INTO THE
WATERS...ALTHOUGH THIS ITERATION WILL LIKELY COME IN WITH A SHORTER
PERIOD OF AROUND 12 TO 13 SECONDS. STILL...FORECASTED HEIGHTS OF
AROUND 6 TO 7 FEET WILL MAKE THIS SWELL SOMETHING TO KEEP AN EYE
BOTH FOR BOATERS AND BEACHGOERS EARLY IN THE WEEK. OTHERWISE...
SEVERAL SMALL SOUTHERLY SWELL GROUPS WILL ALSO CONTINUE TO PROPAGATE
THROUGH THE WATERS OVER THE NEXT WEEK.


&&

.FIRE WEATHER...ONLY SUBTLE CHANGES TO CURRENT FORECAST REGARDING
INCOMING WEATHER SYSTEM. ONE CHANGE WAS TO SLOW DOWN TIMING OF
PRECIP ARRIVAL TO THE COAST TO RIGHT AROUND OR JUST AFTER
MIDNIGHT...WITH SOME MINOR ADJUSTMENTS TO CWR. OTHERWISE STILL ON
TRACK IN TERMS OF EXPECTED QPF AND WINDS. ANTICIPATE A BRIEF
PERIOD OF WINDS GUSTS TO NEAR 30-35 MPH ALONG ELEVATIONS ABOVE
4000K FT BETWEEN MIDNIGHT AND SUNRISE WITH FRONTAL PASSAGE. SOME
ELEVATED VALLEYS AND DRAINAGES IN SOUTH SOUTHWEST ALIGNMENT WILL
ALSO SEE GUSTY WINDS AS WELL. FORTUNATELY THE WINDS WILL BE
ACCOMPANIED OR IMMEDIATELY FOLLOWED BY THE PRECIPITATION. SOME
RESIDUAL SHOWER ACTIVITY IS ANTICIPATED LATER ON SATURDAY WITH
ANOTHER LESS IMPACTFUL AND WEAKER FRONT EARLY SUNDAY MAINLY OVER
THE EXTREME NORTHWEST CORNER OF THE CWA. COOL AND MOIST
CONDITIONS SHOULD CONTINUE THROUGH NEXT WEEK AS A STEADY STREAM OF
TROUGHINESS CONTINUES. SKIES WILL GENERALLY BE SMOKE FREE AT LEAST
THE EARLY PORTION OF NEXT WEEK ALLOWING ANY RESIDUAL FIRE ACTIVITY
TO VENT WELL.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY FROM 1 AM TO 9 AM PDT SATURDAY FOR PZZ450.

     SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 9 AM PDT
     SATURDAY FOR PZZ470.

&&

$$

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