Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 302252
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
352 PM PDT SUN AUG 30 2015

.SYNOPSIS...TEMPERATURES WILL REMAIN NEAR OR BELOW NORMAL FOR THE
NEXT SEVERAL DAYS AS A TROUGH SITS OVER THE WEST COAST.


&&

.DISCUSSION...A WEAK COLD FRONT IS NOW DISSIPATING OVER NORTHWEST
CALIFORNIA. RAINFALL TOTALS RANGED FROM OVER A HALF INCH IN THE
MOUNTAINS OF DEL NORTE COUNTY TO ONLY TENTH ON THE DEL NORTE COAST
AND A FEW HUNDREDTHS IN THE HUMBOLDT BAY AREA. CONDITIONS WILL DRY
OUT THROUGH THE EVENING HOURS WITH MOISTURE POOLING INTO VALLEY
LOCATIONS OVERNIGHT. SOME OVERNIGHT VALLEY FOG WILL BE POSSIBLE IN
MOST AREAS OF NORTHWEST CALIFORNIA EXCEPT SOUTHERN INTERIOR
MENDOCINO WHERE VERY LITTLE RAIN HAS ACCUMULATED OVER THE LAST
COUPLE OF DAYS.

A SMALL SHORTWAVE RIDGE WILL BUILD OVER NORTHWEST CALIFORNIA ON
MONDAY RESULTING IN WARMING TEMPERATURES ACROSS THE INTERIOR AND
BRINGING SOME DRIER AIR...PARTICULARLY ALOFT ON RIDGE TOPS.
ADDITIONALLY...NORTHERLY WINDS WILL INCREASE OVER THE COASTAL
WATERS ALLOWING COOLER AIR TO MIX ONTO COASTAL LAND AREAS REDUCING
AFTERNOON HIGH TEMPERATURES A FEW DEGREES BACK INTO THE 60S.

THE TROUGH WILL REINFORCE ITSELF BEHIND THE SHORTWAVE RIDGE ON
TUESDAY THROUGH THURSDAY OVER THE PACIFIC NORTHWEST ALLOWING
SHORTWAVES TO PINWHEEL SOUTHEAST TOWARD NORTHWEST CALIFORNIA. BOTH
THE GFS AND ECMWF PREDICT SOME LIGHT RAIN TO CLIP DEL NORTE COUNTY
ON WEDNESDAY AS A COLD FRONT WEAKENS OVER THE REGION. CONSIDERING
THIS...HAVE MAINTAINED AND EXPANDED SLIGHT CHANCES FOR RAIN
TUESDAY NIGHT THROUGH WEDNESDAY IN DEL NORTE AND FAR NORTHEASTERN
HUMBOLDT COUNTIES.

MODELS ARE NOW IN VERY GOOD AGREEMENT ON A FINAL VORT MAX MOVING
INTO OREGON AND FAR NORTHERN CALIFORNIA ON THURSDAY...LEADING TO
SHOWER DEVELOPMENT OVER THE INTERIOR MOUNTAINS OF OREGON AND EXTREME
NORTHERN CALIFORNIA. EVEN WITH THE GOOD AGREEMENT...THERE IS
POTENTIAL FOR THIS VORT MAX/UPPER LOW TO SLIDE FARTHER SOUTH THAN
CURRENTLY PREDICTED WHICH COULD BRING SHOWERS TO THE INTERIOR DEL
NORTE...HUMBOLDT...AND TRINITY COUNTIES. FOR NOW THE FORECAST HAS
BEEN KEPT DRY FOR THURSDAY.

A QUICK WARMING AND DRYING TREND WILL BEGIN ON FRIDAY THROUGH THE
WEEKEND AS THE TROUGH AXIS MOVES EAST OF THE REGION ALLOWING LIGHT
OFFSHORE FLOW TO DEVELOP AND TEMPERATURES TO WARM ALOFT. RPA


&&

.AVIATION...LIGHT RAIN SHOWERS ASSOCIATED WITH A WEAK FRONT THAT
PASSED THROUGH THE AREA THIS MORNING HAVE DISSIPATED AS OF 22Z.
CONDITIONS HAVE RANGED FROM IFR TO VFR ACROSS THE AREA TODAY..WITH
LOW CLOUDS LINGERING VC KCEC WITH STRATO-CU ACROSS THE INTERIOR
RIDGES. CIGS SHOULD SCOUR OUT AT KCEC WITHIN THE NEXT COUPLE OF
HOURS WITH VFR CONDITIONS PERSISTING INTO THE EVENING ALONG MUCH OF
THE COAST. GOING INTO THE OVERNIGHT...EXPECT IFR TO MVFR CIGS AND
VSBYS TO DEVELOP. SOME LOW CLOUDS MAY FORM IN THE KLAMATH AND
TRINITY RIVER VALLEYS OVERNIGHT AS WELL WITH THE ADDED LOW LEVEL
MOISTURE FROM THE RECENT RAINS. OTHERWISE...EXPECT GENERALLY VFR TO
PREVAIL ACROSS THE INTERIOR.


&&

.MARINE...SOUTHERLY WINDS HAVE BEGUN TO TURN OUT OF THE NORTH ACROSS
THE SOUTHERN WATERS THIS AFTERNOON AND WILL CONTINUE TO TURN OUT OF
THE NORTH ACROSS ALL OF THE WATERS THIS EVENING. A NW SWELL IS
CONTINUING TO PROPAGATE THROUGH THE WATERS THIS AFTERNOON AND IS
CURRENTLY 3 TO 4 FT AROUND 17 SECONDS. AT THE SAME TIME...NORTHERLY
SHORT PERIOD SEAS WILL BUILD DUE TO INCREASING NORTHERLY WINDS...AND
WILL INTERACT WITH THE NW SWELL PRODUCING A MIXED NW SWELL OF 7 TO
10 FT. SEAS AND WINDS WILL BE HIGHEST ACROSS THE SOUTH...ESPECIALLY
IN THE OFFSHORE WATERS. HAVE ISSUED A SMALL CRAFT ADVISORY FOR THE
SOUTHERN OFFSHORE WATERS STARTING LATE TONIGHT AND GOING THROUGH
TUESDAY MORNING TO REFLECT THE BUILDING CONDITIONS. WINDS AND
RESULTANT SEAS WILL DECREASE SOME BY TUESDAY...WITH LIGHT TO
MODERATE NNW WINDS PREVAILING ACROSS THE WATERS THROUGH MUCH OF THE
WEEK.


&&

.FIRE WEATHER...MOIST CONDITIONS WILL REMAIN IN PLACE TONIGHT AS A
FRONT DISSIPATES OVER NORTHWEST CALIFORNIA. WARMER AND DRIER AIR
WILL MOVE INTO THE REGION ON MONDAY AS A WEAK SHORTWAVE RIDGE MOVES
OVERHEAD. MODELS INDICATE A DRY LAYER WILL MIX DOWN ONTO MOUNTAIN
RIDGE TOPS MONDAY NIGHT RESULTING IN LOWER MAX HUMIDITIES. THE NAM
INDICATES RH VALUES INTO THE SINGLE DIGITS WHICH SEEMS TOO LOW.
AFTER COORDINATING WITH THE IMETS...RH WILL LIKELY PEAK EARLY AND
THEN BOTTOM OUT IN THE 30-50 PERCENT RANGE IN THE EARLY MORNING
HOURS. MOISTURE WILL INCREASE AGAIN TUESDAY THROUGH THURSDAY AS
THE TROUGH REINFORCES ITSELF OVER THE WEST COAST AND A WEAK FRONT
BRINGS ANOTHER SHOT FOR LIGHT RAIN IN DEL NORTE COUNTY TUESDAY
NIGHT THROUGH WEDNESDAY.

THE BIGGEST CONCERN WITH REGARD TO FIRE WEATHER WILL BE THE DRYING
TREND PREDICTED FRIDAY THROUGH THE WEEKEND AS THE UPPER TROUGH
MOVES INLAND. TEMPERATURES WILL WARM AND LIGHT OFFSHORE FLOW IS
FORECAST TO DEVELOP. OVERNIGHT RH RECOVERIES WILL SUFFER AGAIN AND
MAY BECOME RATHER POOR LATE IN THE WEEKEND IF MODEL GUIDANCE IS
CORRECT. RPA


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY FROM 3 AM MONDAY TO 9 AM PDT TUESDAY FOR
     PZZ475.

&&

$$

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