Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 161027
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
330 AM PDT WED APR 16 2014

.SYNOPSIS...A WARM FRONT WILL STALL OVER THE REGION TODAY FOR RAIN
AT TIMES. A COLD FRONT WILL CROSS WESTERN WASHINGTON ON THURSDAY.
DRIER WEATHER IS FORECAST ON FRIDAY WITH WEAK HIGH PRESSURE
OVERHEAD. THE NEXT FRONT WILL ARRIVE LATER SATURDAY.

&&

.SHORT TERM...EXPECT RAIN AT TIMES ACROSS WESTERN WASHINGTON TODAY
AS A WARM FRONT STALLS OVER THE REGION. SKIES WILL REMAIN CLOUDY
WITH TEMPS REMAINING IN THE 50S. A COLD FRONT WILL THEN CROSS THE
AREA ON THURSDAY FOR ANOTHER WET DAY. THERE IS LITTLE BREAK IN THE
ACTION AND WILL KEEP CATEGORICAL POPS THROUGHOUT THE PERIOD. THE
COLD FRONT SHOULD EXIT EAST THURSDAY EVENING. ONSHORE FLOW WILL
INCREASE BEHIND THE FRONT AND A PUGET SOUND CONVERGENCE ZONE WILL
LIKELY FORM OVER THE CENTRAL SOUND. SHOWERS WITH THE CONVERGENCE
ZONE MAY LINGER INTO FRIDAY MORNING. OTHERWISE...WEAK HIGH PRES WILL
BRING A PERIOD OF DRIER WEATHER FRIDAY AFTERNOON THROUGH SAT
MORNING. WET WEATHER WILL RETURN SATURDAY AFTERNOON/EVENING AS THE
NEXT COLD FRONT ARRIVES. 33

.LONG TERM...OVERALL CONFIDENCE IN THE LONG TERM PERIOD REMAINS LOW
AS THE MODELS ARE STILL NOT ALIGNED. THE GENERAL PATTERN CONSISTS OF
AN UPPER LOW OVER THE NE PAC WITH A SERIES OF FRONTS CROSSING
WESTERN WA. BUT THE EXACT TIMING OF EACH SYSTEM IS STILL UNCLEAR.
THEREFORE WILL NOT MAKE ANY WIDESPREAD CHANGES FROM THE PREVIOUS
FORECAST. 33

&&

.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.

THE NORTH FORK OF THE STILLAGUAMISH NEAR ARLINGTON IS FORECAST TO
RISE ABOUT A FOOT TODAY...THEN RISE AN ADDITIONAL FOUR FEET ON
THURSDAY WITH A CREST CLOSE TO 9 FEET. THE RIVER LEVEL WILL BEGIN
FALLING LATER THURSDAY NIGHT AND CONTINUE FALLING FRIDAY AS HIGH
PRESSURE MOVES OVER THE AREA.

TOTAL RAINFALL FOR THE SLIDE AREA THROUGH THURSDAY NIGHT WILL BE ON
THE ORDER OF TWO INCHES.

ADDITIONAL FRONTS WILL AFFECT THE SLIDE AREA LATER SATURDAY AND
MONDAY. THESE SYSTEMS ARE NOT EXPECTED TO BE ESPECIALLY WET OR
HYDROLOGICALLY SIGNIFICANT BUT THEY WILL KEEP CONDITIONS WET.

&&

.AVIATION...UPPER LEVEL HIGH PRESSURE OFFSHORE WILL MOVE OVER THE
PAC NW TONIGHT. MODERATE W-SW FLOW ALOFT. A WARM FRONT STALLED
ACROSS WRN WA WILL LIFT N OF THE AREA TONIGHT. A TROUGH AND SURFACE
FRONT ARRIVE THURSDAY. MOIST AT ALL LEVELS AND STABLE. RAIN AT TIMES.

MOSTLY MVFR CIGS 1-2K FT WITH RAIN AT TIMES. VIS LOCALLY DOWN TO
2-3SM ALONG THE COAST AND 3-5SM INTERIOR.

KSEA...S-SW WIND 6-12 KT. RAIN AT TIMES WITH MOSTLY MVFR CIGS
THROUGH THURSDAY...OCCASIONALLY IMPROVING TO A 3-5K FT CIG.

&&

.MARINE...A WARM FRONT STALLED ACROSS THE AREA WILL LIFT NWD TONIGHT
AS THE FLOW LIFTS AHEAD OF AN APPROACHING COLD FRONT. LOW END SMALL
CRAFT WINDS CAN BE EXPECTED OVER THE COASTAL WATERS AND W ENTRANCE
TO THE STRAIT THROUGH THE MORNING BEFORE EASING. WINDS ELSEWHERE
GENERALLY LESS THAN 20 KT.

A STRONGER FRONT WILL BRING SMALL CRAFT ADVISORY WINDS TO MOST OF
THE WATERS ON THURSDAY. GALE FORCE WESTERLIES ARE POSSIBLE IN THE
STRAIT THURSDAY AFTERNOON AND EVENING BUT CONFIDENCE IS LOW. WINDS
EASE FRIDAY AS HIGH PRES BUILDS OVER THE AREA. 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.

PZ...SMALL CRAFT ADVISORY COAST AND WEST ENTRANCE.

&&

$$

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