Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 220342
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
845 PM PDT TUE OCT 21 2014

.SYNOPSIS...A STRONG FRONTAL SYSTEM WILL MOVE THROUGH WESTERN
WASHINGTON TONIGHT AND WEDNESDAY MORNING. HEAVY RAIN WILL FALL IN
THE OLYMPICS AND NORTH CASCADES. THE RAIN WILL TURN TO SHOWERS
WEDNESDAY NIGHT AND THURSDAY. ANOTHER LOW PRESSURE SYSTEM WILL REACH
THE AREA LATE IN THE WEEK.

&&

.SHORT TERM...AT 830 PM THE STRONG FRONTAL SYSTEM WAS JUST INSIDE OF
130W AND PRESSURE GRADIENTS HAVE BEEN RISING WITH WINDY CONDITIONS
ON THE COAST AND IN THE NORTH. DESTRUCTION ISLAND WAS BLOWING A FULL
GALE AND MAY REACH STORM FORCE. WITH SSE WINDS THE WIND OVER LAND
SHOULD BE GUSTING TO 50MPH AND THERE IS A WIND ADVISORY IN EFFECT
FOR THE NORMALLY WINDIER AREAS. THE THUNDERSTORMS THAT WERE TRACKING
INTO VANCOUVER ISLAND HAVE DECREASED AS THE PRECIP HAS BECOME MORE
WIDESPREAD AND STRATIFORM. THE STRONG SLY WINDS ALOFT TONIGHT INTO
THE OLYMPICS SHOULD GIVE AROUND FIVE INCHES OF RAIN AND A FLOOD
WATCH IS IN EFFECT. THE SKOKOMISH RIVER OUGHT TO REACH FLOOD STATE
AROUND 2AM AND A WARNING IS IN EFFECT FOR THAT RIVER. THERE IS ALSO
A WATCH FOR THE NRN CASCADES...BUT THE BULK OF THE RAIN IN THE
CASCADES WILL PROBABLY HOLD OFF TIL LATE TONIGHT THRU WED MORNING.
THE RAIN BECOMES SHOWERY WED EVENING AS THE FRONT CONTINUES TO
SLOWLY PUSH SOUTHEASTWARD. BREEZY AND SHOWERY WEATHER CAN BE
EXPECTED WED NIGHT AND THU AS ONSHORE FLOW AND A LARGE UPPER TROUGH
CONTINUE TO AFFECT THE AREA. LATE IN THE WEEK A DEEP LOW APPROACHES
THE AREA...THE LATEST NAM HAS A 988MB LOW TRACKS NNE INTO THE SRN
OREGON OFFSHORE WATERS BY DAYBREAK SAT.

.LONG TERM...THE OFFSHORE LOW MOVES INLAND SOMEWHERE OVER THE
PACIFIC NW ON SATURDAY BRINGING WET AND WINDY WEATHER TO THE AREA.
POST FRONTAL SHOWERS DECREASE ON SUNDAY...THEN ANOTHER WARM FRONT
AND LOW APPEAR TO BE ON TRACK TO MOVE ACROSS THE AREA MONDAY AND
TUESDAY. MODEL DETAILS DIFFER...BUT IT APPEARS THAT NEXT WEEK WILL
BE WET AND BREEZY WITH MOUNTAIN SNOW LEVELS DECREASING TO AT LEAST
HIGHER PASS LEVEL MIDWEEK AND TEMPERATURES IN THE LOWLANDS COOLING
OFF WHERE HIGHS STRUGGLE TO GET OUT OF THE LOWER TO MID 50S. ALBRECHT

&&

.HYDROLOGY...A FLOOD WARNING IS IN EFFECT FOR THE SKOKOMISH RIVER IN
MASON COUNTY. FLOOD WATCHES ARE IN EFFECT FOR THE OLYMPIC PENINSULA
TONIGHT AND WEDNESDAY...AND FOR SNOHOMISH COUNTY NORTHWARD IN THE
INTERIOR FROM MIDDAY WEDNESDAY INTO WEDNESDAY NIGHT. THE RIVERS IN
THE CASCADES MOST LIKELY TO SEE FLOOD STAGE ARE THE STILLAGUAMISH
RIVER IN SNOHOMISH COUNTY AND THE NOOKSACK RIVER IN WHATCOM COUNTY.

&&

.AVIATION...AN UPPER TROUGH WILL REMAIN OVER THE REGION THROUGH
THURSDAY. A 990 MB SURFACE LOW WILL TRACK INTO CENTRAL VANCOUVER
ISLAND EARLY WEDNESDAY MORNING. THIS SYSTEM WILL BRING STRONG FLOW
ALOFT TO WRN WA. MOIST AND WEAKLY UNSTABLE. RAIN OVER THE COAST WILL
SPREAD INLAND BY MIDNIGHT...HEAVY AT TIMES THROUGH WEDNESDAY. VFR
CIGS INLAND AND MVFR CIGS NEAR THE COAST WILL DETERIORATE TO
WIDESPREAD MVFR CONDITIONS AFTER MIDNIGHT. AN ISOLATED THUNDERSTORM
IS POSSIBLE...ESPECIALLY NEAR THE COAST.

KSEA...SLY WINDS 10-14 KT INCREASING TO 15 KT W/ G25-30 KT AFTER
MIDNIGHT THROUGH WEDNESDAY MORNING...THEN EASING. RAIN INCREASING
AFTER MIDNIGHT WITH CIGS PREDOMINATELY 3K FT BUT MVFR 2-2500 FT AT
TIMES. RAIN WILL BE HEAVY AT TIMES WEDNESDAY MORNING WITH VIS DOWN
TO 2SM. DTM

&&

.MARINE...SATELLITE AND OBS INDICATE LOW PRESSURE OFF THE PAC NW IS
DEEPENING AND ON TRACK TO REACH CENTRAL VANCOUVER ISLAND AS A 990 MB
LOW EARLY WEDNESDAY MORNING. THE STRONG SE PRESSURE GRADIENTS WILL
BRING HIGH END GALE FORCE WINDS TO THE COASTAL WATERS...WITH SOLID
GALES TO THE ENTRANCES TO THE STRAIT...ADMIRALTY INLET...AND NRN
INLAND WATERS. SMALL CRAFT WINDS TO 30 KT ARE EXPECTED IN PUGET
SOUND/CENTRAL STRAIT. WINDS WILL EASE FIRST ALONG THE COAST AFTER 6
AM...THEN ACROSS THE INTERIOR AFTER 9-10 AM. SEAS OVER 15 FEET ARE
ALSO EXPECTED TODAY ALONG WITH ROUGH BAR CONDITIONS.

THERE WILL BE A RELATIVE LULL IN THE STORMY WEATHER IN THE MIDDLE OF
THE WEEK...THEN ANOTHER STRONG WEATHER SYSTEM WILL AFFECT THE WATERS
FRIDAY AND SATURDAY. A DEEP SURFACE LOW IS EXPECTED TO TRACK THROUGH
THE WATERS DURING THIS TIME BUT THERE IS STILL A LOT OF UNCERTAINTY
WITH HOW STRONG THE LOW WILL BE AND WHERE IT WILL GO. DTM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNING SKOKOMISH RIVER IN MASON COUNTY.
     FLOOD WATCH MASON...CLALLAM...JEFFERSON...AND GRAYS
       HARBOR COUNTIES TONIGHT INTO WEDNESDAY AFTERNOON.
     FLOOD WATCH SNOHOMISH...SKAGIT...AND WHATCOM COUNTIES MIDDAY
      WEDNESDAY THROUGH WEDNESDAY NIGHT.
     WIND ADVISORY COAST...ADMIRALTY INLET...SAN JUANS...WESTERN
       WHATCOM...WESTERN SKAGIT.

PZ...GALE WARNING COASTAL WATERS...ENTRANCES TO THE STRAIT OF JUAN
     DE FUCA...NORTHERN INLAND WATERS...AND ADMIRALTY INLET.
    .SMALL CRAFT ADVISORY CENTRAL STRAIT OF JUAN DE FUCA AND PUGET
     SOUND AND HOOD CANAL.
    .SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.

&&

$$

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