Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 202226
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
326 PM PDT SAT SEP 20 2014

.SYNOPSIS...HIGH PRESSURE WILL CONTINUE TO BRING DRY CONDITIONS
AND SEASONABLE TEMPERATURES TO NORTHWEST CALIFORNIA THIS WEEKEND.
EXPECT LOW CLOUDS AND FOG ALONG THE COAST DURING THE NIGHT AND
MORNING WITH PARTIAL CLEARING IN THE AFTERNOON. A TROUGH WILL
BEGIN TO MOVE OVER THE WEST COAST EARLY NEXT WEEK...BRINGING
COOLER TEMPERATURES AND WIDESPREAD RAIN BY THE MIDDLE OF THE WEEK.

&&

.SHORT TERM...2130Z VISIBLE SATELLITE SHOWS CLOUDS ALONG MOST OF
THE IMMEDIATE COAST AND MOSTLY SUNNY SKIES ELSEWHERE. THE CLOUDS
WILL THICKEN ALONG THE IMMEDIATE COAST EARLY THIS EVENING AND
OVERNIGHT. VISIBILITIES SHOULD DROP IN THESE LOCATIONS AS FOG
DEVELOPS. EXPECT PARTIAL CLEARING BY SUNDAY AFTERNOON. OTHERWISE,
HIGH PRESSURE WILL CONTINUE TO BRING DRY CONDITIONS AND SEASONABLE
TEMPERATURES TO NORTHWEST CALIFORNIA THROUGH SUNDAY. A PACIFIC
TROUGH WILL BEGIN TO MOVE OVER THE WEST COAST ON MONDAY, BRINGING
COOLER TEMPERATURES AND SOME HIGH CLOUDS.

.LONG TERM (TUE MORNING-SATURDAY)...MODELS CONTINUE TO BE IN
OVERALL AGREEMENT BUT ONLY NOW THROUGH WEDNESDAY AFTERNOON AS THE
NEXT SIGNIFICANT TROUGH APPROACHES AND IMPACTS THE COAST. EC IS A
LITTLE FASTER WITH TIMING OF FRONT BRINGING IT INTO CEC BY TUE
EVENING WHILE GFS BRINGS IT IN A LITTLE BEFORE SUNRISE WED
MORNING. I WILL LEAN TOWARD TIMING OF GFS WITH FRONTAL PASSAGE
THROUGH ALL OF TRINITY AND MENDO COUNTY BY WED EVENING. PWATS
AHEAD OF FRONT ARE BETWEEN 1-1.5 INCHES AND THE INTEGRATED WATER
VAPOR TRANSPORT (IVT) WHICH COMBINES THE MOISTURE AND WIND IS ALSO
HIGH WITH A RETURN INTERVAL OF 10 YEARS NEAR CEC AND 5 YEARS DOWN
NEAR UKIAH. WITH GOOD MOISTURE AND DYNAMICS COULD SEE BRIEF
PERIODS OF HEAVY RAIN WITH THE FRONT. WITH THE INCREASING
SOUTHERLY WINDS AHEAD OF THE FRONT, SHOULD SEE SOME GUSTY WINDS
ESPECIALLY OVER THE HIGHER RIDGES DURING THE DAY WED. BEHIND
FRONT, MODELS ARE DIFFERING WITH WHAT TO DO WITH THE ASSOCIATED
TROUGH. GFS SWINGS IT THROUGH ON THURSDAY WITH RIDGE BUILDING OVER
THE WEEKEND WITH A RETURN TO DRY WEATHER. EC IS SLOWER AND DEEPER
WITH THE BROAD TROUGH STILL OVER THE AREA THROUGH THE WEEKEND
WHICH COULD KEEP SHOWERS GOING. WENT WITH WPC`S THINKING WHICH
SWINGS THE TROUGH THROUGH LIKE THE GFS THOUGH A LITTLE SLOWER.
WILL HAVE TO WATCH THE LARGE AREA OF HIGH PRESSURE IN THE EASTERN
US TO SEE IF IT SLOWS DOWN THE TROUGH OR CUTS IT OFF AS IT COMES
INTO THE WEST COAST. WPC`S STILL FORECASTING ABOUT 2.5 INCHES OF
RAIN NEAR CEC FOR THE ENTIRE STORM SYSTEM AND AT LEAST 0.50 INCHES
EVERYWHERE ELSE. COLDER AIR WITH THE TROUGH AS 850MB TEMPS DROP
DOWN TO ABOUT 5C AND VERY HIGHEST PEAKS COULD GET A DUSTING OF
SNOW. LAPSE RATES DO NOT LOOK STEEP ENOUGH FOR ANY THUNDERSTORMS
BUT WILL STILL NEED TO KEEP AN EYE ON IT. DEAN

&&

.AVIATION...2130Z VISIBLE SATELLITE SHOWS CLOUDS ALONG MOST OF
THE IMMEDIATE COAST, BRINGING LIFR, AND MOSTLY SUNNY SKIES WITH
VFR ELSEWHERE. ALONG THE IMMEDIATE COAST...EXPECT THE CLOUDS TO
THICKEN EARLY THIS EVENING AND OVERNIGHT. VISIBILITIES ARE
EXPECTED TO DROP IN MOST LOCATIONS AS FOG DEVELOPS.
INLAND...EXPECT VFR TO PREVAIL, EXCEPT FOR SOUTHERN MENDOCINO
COUNTY WHERE VALLEY CLOUDS/FOG MAY DEVELOP LATE.

&&

.MARINE...THE SMALL CRAFT ADVISORY FOR THE NORTHERN OUTER WATERS
HAS BEEN ALLOWED TO EXPIRE THIS AFTERNOON AS WINDS AND SEAS HAVE
FALLEN BELOW ADVISORY LEVELS.

ELONGATED LOW PRESSURE OFF THE OR/CA BORDER HAS BEEN MAINTAINING
FRESH SOUTHERLY WINDS AROUND CAPE MENDOCINO TODAY. A LATE MORNING
ASCAT PASS CONFIRMED THE EARLY MORNING FORECAST WITH 20 KT WINDS
AROUND THE CAPE. WHILE AT BUOY 22 THE GUSTS HAVE PROVEN TO BE WELL
FORECAST AT AROUND 25 KT. AS THIS LOW LIFTS TO THE NW AND FILLS
OVER THE NEXT SEVERAL HOURS, THE WINDS WILL COME DOWN WHICH IN
TURN WILL ALLOW FOR THE STEEP SOUTHERLY WAVES TO SUBSIDE.
OTHERWISE, A NW SWELL REMAINS THE MAIN HEIGHT PLAYER IN THE SEA
STATE, RUNNING AROUND 7 FT AT 12 SECONDS THIS AFTERNOON. THIS
SWELL WILL SLOWLY SUBSIDE THROUGH SUNDAY. SUNDAY AND MONDAY SHOULD
HAVE GENERALLY LIGHT TO MODERATE WINDS AND SEAS AROUND 3 TO 4 FT
AT 10 SECONDS.

TUESDAY WILL BE A TRANSITION DAY AS AN APPROACHING FRONT BRINGS
WINDS TO THE SOUTH AND INCREASES OVERNIGHT. BY LATE TUE INTO WED,
EXPECT WINDS INTO THE 15 TO 25 KT RANGE WITH RESULTANT STEEP
SOUTHERLY WAVES. AT THE SAME TIME A POST FRONTAL WESTERLY SWELL,
WHICH IS OUT RUNNING THE SPEED OF THE FRONT, WILL BEGIN TO BUILD
INTO THE WATERS, PEAKING OUT AROUND 12 FT AT 15 SECONDS OVERNIGHT
WED INTO THU. WHILE SMALL CRAFT ADVISORIES WILL BE NEEDED BY
MIDWEEK FOR ALL WATERS, WE`LL BE WATCHING FOR THE POSSIBILITY OF
HOISTING A HAZARDOUS SEAS WARNING FOR THE NORTHERN OUTER WATERS.
CONDITIONS WILL SUBSIDE AS QUICKLY AS THEY BUILT ON THU INTO FRI.
MODEL SHOW NW CAL SLIDING UNDER A WEAK PRESSURE GRADIENT WHICH
WILL ALLOW FOR EASING WINDS AND SUBSIDING STEEP WAVES. TIMING
REMAINS A LITTLE FUZZY WITH THE ONSET AND SUBSIDING OF THE WORST
CONDITIONS, BUT REGARDLESS MIDWEEK IS LOOKING NOT SO NICE TO BE
OUT TO SEA. KEEP AN EYE ON THE FORECAST AND THIS DISCUSSION FOR
THE LATEST INFO. BFG

&&

.EKA WATCHES/WARNINGS/ADVISORIES...

CA...NONE.

NORTHWEST CALIFORNIA COASTAL WATERS...

SMALL CRAFT ADVISORY FOR PZZ470.

&&

$$

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