033 
FXUS66 KEKA 192230
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
330 PM PDT TUE MAR 19 2013

.SYNOPSIS...A STORM SYSTEM WILL BRING RAIN AND GUSTY WINDS
TONIGHT THROUGH WEDNESDAY. DRY AND COOLER WEATHER WILL RETURN
ON THU AND FRI AS HIGH PRESSURE REBUILDS INTO THE REGION.

&&

.DISCUSSION...SURFACE ANALYSIS AND SATELLITE IMAGERY SHOWED A 
MOIST PLUME TAKING AIM ON THE REGION THIS AFTERNOON. PRECIP
HAS BEEN SLOWLY INCREASING IN COVERAGE AND INTENSITY THROUGH
THE DAY AS A POSITIVE TILTED UPPER TROUGH WEST OF 130W SLOWLY
DIGS SOUTH AND EAST TOWARD THE AREA. SO FAR AMOUNTS HAVE BEEN
LIGHT AND SPOTTY ALONG THE COAST BUT WITH GREATER COVERAGE AND
HIGHER RAIN RATES INLAND. RATES SHOULD SLOWLY INCREASE LATER TONIGHT
AS A COLD FRONT APPROACHES THE COASTLINE. CONCERNED THAT THE
GREATER EUREKA AREA MIGHT BE DRY SLOTTED TONIGHT AS STRONG SOUTHERLY
WINDS RAMP UP AHEAD THE COLD FRONT. THIS WILL REDUCE THE RAINFALL
AMOUNTS UNTIL THE SURFACE BOUNDARY MOVES ONSHORE AND WINDS SHIFT
AROUND TO THE WEST BY 12PM WED. IF A REFLECTIVITY HOLE OPENS UP WE
MAY SEE ONLY A FEW SPOTTY HUNDREDTHS IN AND AROUND EUREKA. WE ARE
STILL LOOKING AT A FAIRLY GOOD SOAKING CWA-WIDE THE NEXT 24
HOURS...WITH GENERALLY 0.75-1.5 INCHES WITH LOCALIZED AMOUNTS UP
TO 2.5 INCHES IN THE MOUNTAINS. MOST OF THE RAIN WILL OCCUR AHEAD
OF AND ALONG THE COLD FRONTAL BOUNDARY WHICH LOOKS TO PASS THROUGH
BY MIDDAY WED...WITH AN HOUR OR TWO OF MODERATE TO HEAVY RAIN.

SNOW LEVELS WITH THIS SYSTEM WILL REMAIN ABOVE 6KFT UNTIL THE
UPPER TROUGH PASSES OVER LATE WED AFTERNOON INTO EARLY EVENING.
2-4 INCHES OF NEW SNOW IS EXPECTED ABOVE 5500 FEET WED
AFTERNOON...WHICH MAY AFFECT SCOTT MOUNTAIN PASS LATE IN THE DAY.
THE PRECIP WILL TRANSITION TO SCATTERED SHOWERS BEHIND THE FRONT
LATE WED AFTERNOON AND DIMINISH WED NIGHT INTO THU. SNOW LEVELS
SHOULD PLUMMET TO 2500-3500 FT WED NIGHT...HOWEVER THE
INSTABILITY...MOISTURE AND DYNAMICS IN THE COLD AIR BEHIND THE
FRONT DOES NOT LOOK VERY FAVORABLE FOR HEAVY SNOW SHOWERS. A
WINTER WEATHER ADVISORY IS NOT ANTICIPATED AT THIS TIME DUE TO
INSUFFICIENT AMOUNTS AND SPARSE COVERAGE.

DEPENDING ON THE RATE OF CLEARING AND DRYING...WIDESPREAD FROST IS
POSSIBLE EARLY THU MORNING. DRYING NORTH FLOW AND CLEARING SKIES
SHOULD CONTINUE INTO FRI AND WIDESPREAD FROST LOOKS MORE LIKELY
EARLY FRI MORNING.

MODELS HAVE BEEN INDICATING A MINOR SHORT WAVE CLIPPING THE
EXTREME NORTHERN PORTION OF THE FORECAST AREA ON THU. 
THEREFORE...KEPT A SLIGHT CHANCE OF PRECIP IN DEL NORTE COUNTY ON
THU. THE MODELS WERE IN BETTER AGREEMENT FRI WITH A RIDGE
INTENSIFYING AFTER S/W PASSAGE. IT SHOULD BE BREEZY AND COOL ON
FRIDAY...ESPECIALLY AT THE COAST. MODELS INDICATE ANOTHER WEAK S/W
CLIPPING THE AREA SAT OR SAT NIGHT FOR ANOTHER SLIGHT CHANCE OF
LIGHT PRECIP MAINLY NORTH OF THE CAPE. A RIDGE SHOULD THEN BUILD
AGAIN ON SUN...KEEPING THE AREA DRY THROUGH MON. 12Z GFS AND
ECMWF BRING A STRONGER/DEEPER TROUGH TOWARD THE COAST ON TUE FOR
ANOTHER LOW CHANCE OF RAIN.

&&

.AVIATION...CLOUDS WERE PREDOMINANTLY MID LEVEL TODAY ACROSS THE
REGION AS A WEATHER SYSTEM APPROACHED NORTHERN CALIFORNIA. LIGHT
SPRINKLES OCCURRED OVER SOUTHERN MENDOCINO EARLY A.M. A LARGE
SWATHE OF LIGHT RAIN INVADED THE REGION SHORTLY BEFORE NOON...
BRINGING LIGHT RAIN FROM FROM CEC-UKI. HOWEVER SOME MODERATE RAIN
DID FALL IN REDWAY/GARBERVILLE VICINITY. 2PM RADAR AND SAT
PICTURES SHOW WIDESPREAD LIGHT PRECIPITATION ADVANCING TOWARD
COAST AGAIN. CIGS/VIS CONTINUED TO SHOW VFR CONDITIONS UNTIL
AROUND 3PM WHEN ACV/CEC REPORTED MVFR CIGS/VIS. WINDS REMAINED
SOUTHERLY AS EXPECTED...AND SHOULD INCREASE IN INTENSITY TONIGHT
AS THE PACIFIC FRONT MOVES TOWARDS THE AREA. EXPECT MVFR AND EVEN
OCNL IFR THROUGH THE EVENING MAINLY AT COASTAL LOCATIONS.

&&

.MARINE...A STRONG SYSTEM CONTINUES TO MOVE INTO THE AREA INCREASING 
SOUTHERLY WINDS AHEAD OF A PRE-FRONTAL TROUGH. A COASTAL JET WITH 
45-50 KT WINDS APPROXIMATELY 2KM ABOVE THE SURFACE WILL CONTINUE TO 
DEVELOP OVERNIGHT INTO EARLY WEDNESDAY MORNING. THIS WILL ALLOW GALE 
FORCE GUSTS TO MIX TO THE SURFACE WITH GUSTS APPROACHING 45 KT 
ACROSS THE NORTHERN OUTER WATERS. THE COASTAL JET STAYS PRIMARILY 
NORTH OF THE CAPE AS THE PRIMARY ENERGY OF THE SYSTEM MOVES INTO THE 
PACIFIC NORTHWEST. THUS GALE WARNINGS ARE ISSUED FOR BOTH NORTHERN 
WATER ZONES WHILE ONLY SMALL CRAFT ADVISORIES ARE UP FOR THE 
SOUTHERN WATER ZONES. SEAS WILL BUILD RAPIDLY IN RESPONSE TO THE 
WINDS...PEAKING BETWEEN 12 AND 14 FT OVER THE NORTHERN OUTER WATERS. 
ALL ADVISORIES AND WARNINGS HAVE BEEN EXTENDED A FEW HOURS LATER 
INTO THE MORNING ON WEDNESDAY AS MODELS HAVE SLOWED DOWN EVEN MORE 
THAN THEY WERE ANTICIPATED TO SLOW DOWN YESTERDAY.

THE PRIMARILY COLD FRONT WILL MOVE TOWARD THE COAST WEDNESDAY 
MORNING DISSIPATING THE COASTAL JET. THE FRONT WILL MOVE THROUGH THE 
WATERS DURING THE DAY WEDNESDAY TURNING THE WINDS OUT OF THE 
NORTHWEST AND ALSO BRING A BUILDING NORTHWEST SWELL. SEAS WILL 
SUBSIDE ENOUGH ACROSS THE SOUTHERN WATERS FOR A PERIOD OF BELOW SCA 
CRITERIA SEAS AND WINDS AS THE SOUTHERLY WINDS DIMINISH JUST AHEAD 
OF THE FRONT. HOWEVER THESE LOWER CONDITIONS WILL BE SHORT LIVED AS 
THE NORTHWEST SWELL BUILDS IN AND THEN HIGH PRESSURE STRENGTHENS 
OVER THE EASTERN PACIFIC BEHIND THE COLD FRONT. THIS WILL CAUSE 
NORTHERLY WINDS TO STRENGTHEN WEDNESDAY NIGHT INTO THURSDAY. SCA TO 
NEAR GALE CONDITIONS ARE ANTICIPATED ACROSS THE SOUTHERN WATERS 
THURSDAY INTO THE WEEKEND...WITH SCA CONDITIONS EXTENDING NORTH OF 
THE CAPE.

MODELS ARE NOW IN BETTER AGREEMENT ON THE EXTENDED FORECAST... 
ANTICIPATING A RIDGE OF HIGH PRESSURE TO PERSIST JUST OFF OR 
OVER THE WEST COAST THROUGH THE WEEKEND. ANOTHER TROUGH WILL
LIKELY ADVANCE TOWARD THE COAST NEXT WEEK. RPA



&&

.EKA WATCHES/WARNINGS/ADVISORIES...CA...NONE. 

NORTHWEST CALIFORNIA COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL
     11 PM PDT THIS EVENING PZZ450.

     GALE WARNING FROM 11 PM THIS EVENING TO 7 AM PDT WEDNESDAY 
     PZZ450.

     GALE WARNING UNTIL 7 AM PDT WEDNESDAY PZZ470.

     SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 7 AM PDT 
     WEDNESDAY PZZ455.

     SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 7 AM PDT 
     WEDNESDAY PZZ475.

&&

$$

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