Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 142321
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
330 PM PST SUN FEB 14 2016

.SYNOPSIS...MILD AND WET WESTERLY FLOW ALOFT WILL PERSIST OVER THE
AREA THROUGH TUESDAY FOR LOCALLY HEAVY RAIN AT TIMES. TEMPERATURES
WILL BE ABOVE NORMAL. A TROUGH WILL BRING MORE SHOWERS AND COOLER
WEATHER WEDNESDAY AND THURSDAY. ANOTHER FRONT WILL ARRIVE ON FRIDAY.

&&

.SHORT TERM...STRONG MOIST WESTERLY FLOW CONTINUES ACROSS WESTERN
WASHINGTON WITH A VERY MILD AIR MASS OVER THE REGION. THERE HAVE
BEEN A FEW BREAKS TODAY BUT RAIN WILL INCREASE IN INTENSITY TONIGHT
INTO MONDAY AS THE NEXT WAVE ARRIVES...CURRENTLY BACK OF 130W. THE
COAST AND THE WEST SLOPES OF THE OLYMPICS AND CASCADES WILL GET HIT
THE HARDEST. MODELS SHOW SEVERAL INCHES OF PRECIP IN THE MOUNTAINS
AS A DEEP MOISTURE PLUME SLAMS INTO THE REGION...ALONG WITH STRONG
850 MB UPSLOPE FLOW OF 30-50KT. THE GFS REMAINS THE WETTEST SOLUTION
WITH 4-7 INCHES POSSIBLE...WITH 3-5 IN THE NAM. MODELS SHOW THE
MOISTURE BAND WAVERING BETWEEN SOUTHERN B.C. AND WESTERN WA MONDAY
NIGHT...SHIFTING THE HEAVY QPF BULLSEYES. THERE IS STILL SOME
UNCERTAINTY AND A FLOOD WATCH WILL BE ISSUED. RIVERS WILL BE RISING
AND A FEW RIVERS WILL BE CLOSE TO FLOOD STAGE MONDAY MORNING. AN
UPPER LEVEL TROUGH OVER THE NE PAC MAY BREAK THE MOISTURE TAP ON
TUESDAY WITH STEADY HEAVY RAIN ENDING. 33

TOTAL RAINFALL AMOUNTS IN THE INTERIOR WILL RANGE FROM 0.50-1.00
INCHES. TEMPERATURES WILL MAINLY STICK IN THE 50S.

AN UPPER LEVEL TROUGH WILL SHIFT INLAND WEDNESDAY OR WEDNESDAY NIGHT
FOR ADDITIONAL SHOWERS AND COOLER CONDITIONS. 33

.LONG TERM...SHOWERS WILL CONTINUE INTO THURSDAY WITH A TROUGH OVER
THE REGION. ANOTHER PAC FRONTAL SYSTEM WILL ARRIVE ON FRIDAY. BUT
THERE IS A CHANCE THAT THIS SYSTEM WILL SPLIT/WEAKEN WHILE MOVING
INLAND. THE ECMWF STILL PROMISES A RIDGE NEXT WEEKEND FOR A BREAK IN
THE ACTION. THE WET GFS KEEPS MOIST SOUTHWEST FLOW OVER THE AREA FOR
MORE RAIN. NO MAJOR CHANGES WERE MADE TO THE EXTENDED FORECAST
JUST YET. 33

&&

.HYDROLOGY...A FLOOD WATCH IS IN EFFECT FOR THE WEST SLOPES OF THE
CASCADES AND FOR THE SKOKOMISH RIVER IN MASON COUNTY.

A PLUME OF MOISTURE IS STEERED DIRECTLY AT WESTERN WA WITH PERIODS
OF HEAVY RAIN EXPECTED TONIGHT THROUGH TUESDAY MORNING. TOTAL
RAINFALL AMOUNTS MAY BE AS HIGH AS 5-7 INCHES IN THE CASCADES. SO
FAR THE HEAVIEST HIT LOOKS TO BE THE CENTRAL AND NORTHERN CASCADES
FROM KING COUNTY NORTH. THE RIVERS FLOWING OFF THE WEST SLOPES OF
THE CASCADES WILL SEE RISES AND A FEW RIVERS WILL BE CLOSE TO FLOOD
STAGE...WITH FLOODING POSSIBLY AS EARLY AS MONDAY MORNING.

THE SKOKOMISH RIVER IN MASON COUNTY CONTINUES TO RUN HIGH FROM HEAVY
RAIN ON FRIDAY AND SATURDAY. THE WIND FLOW IS NOT IDEAL FOR HEAVY
PRECIP IN THE BASIN BUT IT IS BORDERLINE. A LITTLE BIT OF RAIN IS
ALL IT TAKES TO PUSH THIS RIVER BACK INTO FLOOD STAGE.

&&

.AVIATION...A CONVEYOR BELT OF MOIST AIR WILL CONTINUE TO STREAM IN
ON STRONG W-NW WINDS ALOFT AROUND THE PERIPHERY OF A FLAT UPPER
RIDGE. DEEP-LAYER MOISTURE AND CLOUDS WILL CONTINUE THROUGH MON
MORNING. AIR MASS ABOVE 100 WILL DRY OUT SOME ON MON AFTN...BUT THE
LOWER ATMOSPHERE WILL REMAIN RICHLY MOIST FOR THE NEXT 30 HOURS WITH
WIDESPREAD CIGS BELOW 020...EVEN BELOW 010 AT TIMES. WIDESPREAD MTN
OBSCURATION.

KSEA...CIGS WILL REMAIN BELOW 020 FOR THE NEXT 30 HOURS...EVEN
FALLING BELOW 010 AT TIMES. A FRONT DRAPED ACROSS NW WA IS CURRENTLY
BECOMING ENERGIZED AND STRENGTHENING S/SW SFC WINDS AT THE TERMINAL.
GUSTS OF 30+ KT WILL BE COMMON THIS EVNG AND OVERNIGHT.
OTHERWISE...RAIN HAS LARGELY AVOIDED THE TERMINAL THIS AFTN...BUT
RAIN WILL FILL BACK IN OVER THE NEXT 3 HOURS...BRINGING A RETURN OF
REDUCED VSBY. HANER

&&

.MARINE...FRONT LIFTING NORTH THROUGH THE WATERS RIGHT NOW...WITH
STRONG SW GRADIENTS FILLING IN SOUTH OF THE FRONT. THIS WILL BRING
INCREASING SOUTHERLIES BOTH COAST AND INTERIOR WATERS THIS
EVNG...WITH SMALL CRAFT WESTERLIES FROM THE STRAIT AND THEN UP
ACROSS THE SAN JUANS TO BELLINGHAM DEVELOPING THIS EVNG. THE FRONT
WILL SLIP BACK SOUTH ON MONDAY MORNING...BRINGING A DECEIVING LULL
IN WIND NORTH OF JAMES ISLAND ALONG THE COAST AND NORTH OF CAMANO
ISLAND OVER THE INTERIOR. HOWEVER...THE FRONT WILL LIFT BACK NORTH
AGAIN ON MON AFTN...BRINGING EVEN STRONGER S/SW GRADIENTS ON MON
AFTN AND EVNG. WINDS QUICKLY COME DOWN LATE MON NGT AS A BRIEF HIGH
PRES RIDGE BUILDS INTO WRN WA.HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WATCHES IN EFFECT.

PZ...SMALL CRAFT ADVISORY FOR ROUGH BAR UNTIL 1 PM PST MONDAY FOR
     GRAYS HARBOR BAR.

     SMALL CRAFT ADVISORY ALL WATERS EXCEPT ADMIRALTY INLET.

&&

$$

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