Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 200412
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT SAT APR 19 2014

.SYNOPSIS...SHOWERS AND ONSHORE FLOW WILL DIMINISH OVERNIGHT AS HIGH
PRESSURE MOVES INTO THE AREA. THE NEXT FRONT WILL STALL OFFSHORE
SUNDAY WITH A CHANCE OF RAIN ALONG THE COAST. THE FRONT WILL MOVE
INLAND MONDAY NIGHT. ADDITIONAL WEATHER SYSTEMS WILL GIVE COOL
UNSETTLED WEATHER THROUGH NEXT WEEK.

&&

.SHORT TERM...SHOWERS AND BREEZY WEATHER TONIGHT WILL GIVE WAY TO
WEAK HIGH PRESSURE SUNDAY. THE NEXT INCOMING FRONT WILL STALL SUNDAY
JUST OFFSHORE AND BECOMING NORTH-SOUTH ORIENTED...WHICH WILL THE
BEST CHANCE OF PRECIP TO THE COAST. AN UPPER TROUGH WILL APPROACH
THE AREA MONDAY AND PUSH INLAND MONDAY NIGHT INTO TUESDAY.
SSW FLOW ALOFT AHEAD OF THIS TROUGH AND THE OLD STATIONARY FRONTAL
SYSTEM WILL GIVE A CHANCE OF SHOWERS TO THE AREA MONDAY....WITH AN
INCREASING CHANCE MONDAY AFTERNOON AND NIGHT AND EVEN MORE SO ON
TUESDAY.

.LONG TERM...MODELS DIVERGE SOMEWHAT CONCERNING THE WEATHER ON
WEDNESDAY. THE GFS FAMILY OF SOLUTIONS GENERALLY SHOWS DIRTY RIDGING
ON WEDNESDAY FOR POSSIBLY SOME PEEKS OF SUNSHINE AND ONLY A CHANCE
OF SHOWERS...MAINLY IN THE MOUNTAINS...IN WESTERLY FLOW ALOFT. THE
PREFERRED ECMWF AND CANADIAN SOLUTIONS SHOW A WARM FRONT BRINGING
RATHER WET CONDITIONS TO THE AREA...ESPECIALLY LATER IN THE DAY ON
WEDNESDAY. MODELS ARE FAIRLY CONSISTENT IN BRINGING A SLOW MOVING
COLD FRONT THROUGH THE AREA WEDNESDAY NIGHT THROUGH THURSDAY NIGHT
OR FRIDAY FOR PERIODS OF RAIN. A TROUGH PATTERN WILL GIVE AT LEAST
A CHANCE OF SHOWERS TO THE AREA NEXT WEEKEND. POPS THROUGH THE
EXTENDED FORECAST ARE ABOVE CLIMATOLOGICAL AVERAGE AND TEMPERATURES
WITH ALL THE CLOUDS AND PRECIPITATION WILL AVERAGE A FEW DEGREES
BELOW NORMAL FOR LATE APRIL. ALBRECHT

&&

.HYDROLOGY...RIVER FLOODING IS UNLIKELY FOR THE NEXT 7 DAYS.

THE EXCEPTION IS THE NORTH FORK OF THE STILLAGUAMISH RIVER EAST OF
THE SR 530 LANDSLIDE NEAR OSO WHERE A FLOOD WARNING REMAINS IN
EFFECT UNTIL FURTHER NOTICE. FLOODING CONTINUES FOR THIS RIVER AS A
RESULT OF WATER POOLED BEHIND THE DEBRIS DAM THAT PARTIALLY BLOCKS
THE RIVER.

AT 230 PM...THE NORTH FORK OF THE STILLAGUAMISH NEAR ARLINGTON IS AT
4.6 FT...OR 2740 CFS. THE RIVER IS EXPECTED TO RISE TO 6.5 FEET OR
6050 CFS EARLY SUNDAY MORNING BEFORE FALLING BACK TO AROUND 4.5 FEET
MONDAY AFTERNOON. THE NORTH FORK OF THE STILLAGUAMISH RIVER NEAR OSO
IS AT 216.5 FEET OR 1900 CFS THIS AFTERNOON AND IS EXPECTED TO RISE
TO 218.3 FEET OR 3500 CFS EARLY SUNDAY MORNING BEFORE FALLING LATE
SUNDAY INTO MONDAY. THE SLIDE POOL EAST OF THE LANDSLIDE IS EXPECTED
TO RISE TO AROUND 285.3 FT MIDDAY SUNDAY BEFORE FALLING BACK TO
284.3 FT MONDAY NIGHT. ALBRECHT

&&

.AVIATION...AN UPPER LEVEL TROUGH OVER THE PAC NW WILL SHIFT EWD
TONIGHT...THEN A TEMPORARY RIDGE BUILDS ON SUNDAY. MODERATE WLY FLOW
ALOFT...BECOMING LIGHT TO MODERATE SLY FLOW ON SUNDAY. DECREASING
MOISTURE LATE TONIGHT WITH DRYING IN THE LOWER AND MID LEVELS
SUNDAY. WEAKLY UNSTABLE THIS EVENING...THEN STABLE. MAINLY VFR
CONDITIONS THROUGH SUNDAY...EXCEPT BRIEF MVFR CIGS WITH ANY SHOWERS
THIS EVENING.

KSEA...CIGS 3-5K FT TONIGHT...THEN ABOVE 6-8K FT SUNDAY MORNING
BEFORE SCATTERING. LINGERING SHOWERS THIS EVENING...ENDING
OVERNIGHT. DRY SUNDAY. SW WIND 13-18 KT W/ GUSTS 25 KT...EASING TO
10-13 KT LATER TONIGHT. S WIND TO 10 KT ON SUNDAY. DTM

&&

.MARINE...HIGHER SURFACE PRESSURE BUILDS OVER THE WATERS BEHIND A
FRONT TONIGHT. SMALL CRAFT ADVISORY WINDS REMAIN OVER ALL
WATERS...TAPERING OFF BY LATE TONIGHT. SE SMALL CRAFT WINDS
REDEVELOPING OVER THE COASTAL WATERS AND W STRAIT ON SUNDAY. HIGH
PRESSURE REMAINS OVER THE WATERS SUNDAY AS A FRONT APPROACHES...THEN
DIMINISHES AS IT PUSHES ACROSS THE AREA SUNDAY NIGHT.

A LARGE SWELL TRAIN WILL ARRIVE ALONG THE WASHINGTON COAST TONIGHT
AND CONTINUE INTO SUNDAY. LARGE WAVES UP TO 15 FEET WILL IMPACT THIS
COAST TONIGHT...BUILDING TO 16 TO 19 FEET LATER TONIGHT INTO SUNDAY
MORNING. A HIGH SURF ADVISORY REMAINS IN EFFECT FOR THE COAST
THROUGH SUNDAY. THIS IS A RAZOR CLAM DIG WEEKEND FOR TWIN
HARBORS...COPALIS AND MOCLIPS/MOCROCKS BEACHES. EXTREME CAUTION
SHOULD BE EXERCISED AS WAVES WILL LIKELY RACE FURTHER UP THE BEACH
THAN NORMAL. DTM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNING REMAINS IN EFFECT FOR THE NORTH FORK OF THE
      STILLAGUAMISH RIVER EAST OF THE SR 530 LANDSLIDE.
      HIGH SURF ADVISORY NORTH AND CENTRAL COAST THROUGH SUNDAY
      AFTERNOON.

PZ...SMALL CRAFT ADVISORY CENTRAL AND EASTERN STRAIT OF JUAN DE
     FUCA...ADMIRALTY INLET...AND THE NORTHERN INLAND WATERS THROUGH
     MIDNIGHT TONIGHT.
     SMALL CRAFT ADVISORY COAST AND WEST STRAIT OF JUAN DE FUCA
     THROUGH SUNDAY.
     SMALL CRAFT ADVISORY PUGET SOUND THROUGH 2 AM PDT SUNDAY
     MORNING.
     SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR THROUGH SUNDAY.

&&

$$

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