Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 131726
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
930 AM PST SAT FEB 13 2016

.SYNOPSIS...A PAIR OF WARM FRONTS WILL BRING RAIN...LOCALLY HEAVY AT
TIMES...TO THE AREA THIS AFTERNOON THROUGH SUNDAY. MOIST WESTERLY
FLOW ALOFT WILL CONTINUE THROUGH EARLY NEXT WEEK.

&&

.SHORT TERM...A WARM FRONT WILL SPREAD RAIN INLAND TODAY FOR ANOTHER
ROUND OF WET WEATHER. RAIN WILL BE HEAVY AT TIMES ALONG THE COAST
WITH UP TO 1 INCH EXPECTED. THE OLYMPICS WILL SEE 1-3 INCHES AND A
FLOOD WATCH REMAINS IN EFFECT FOR THE SKOKOMISH RIVER IN MASON
COUNTY. PRECIP AMOUNTS WILL RANGE FROM 0.25-0.50 IN THE
INTERIOR...WITH HIGHER AMOUNTS POSSIBLE IN THE SOUTHWEST INTERIOR.
WINDS ALOFT WILL TURN WESTERLY BEHIND THE WARM FRONT THIS EVENING
WITH HEAVY PRECIP FOCUSED ALONG THE CASCADES. SNOW LEVELS ARE AROUND
4000-5000 FEET WITH HEAVY SNOW POSSIBLE AT PARADISE AND MOUNT BAKER.
CURRENT FORECAST LOOKS GOOD.

STRONG MOIST WESTERLY FLOW WILL CONTINUE TOMORROW THROUGH EARLY NEXT
WEEK. THE AIR MASS WILL REMAIN MILD WITH TEMPERATURES MAINLY IN THE
50S. MODELS SHOW A PLUME OF MOISTURE AIMED ON WESTERN WA AND
SOUTHERN B.C. WITH POSSIBLE HEAVY PRECIP IN THE MOUNTAINS. SNOW
LEVELS ARE AROUND 6000 FEET. THE PRECIP BULLSEYES ARE WAVERING IN
THE MODELS BUT MAY SEE SEVERAL INCHES OF RAIN IN THE
CASCADES...ESPECIALLY THE NORTHERN CASCADES. 33

.LONG TERM...PREVIOUS DISCUSSION...COULD IT BE THAT GFS AND ECMWF
ARE BEGINNING TO COALESCE. GENERALLY STARTING TO LOOK THAT
WAY...ALTHOUGH SOME OF THE DETAILS ARE OFF. FLAT RIDGING LOOKS TO BE
IN PLACE FOR THE START OF NEXT WEEK...BUT ENOUGH MOISTURE PRESENT TO
LEAVE POPS IN...ALBEIT A BIT MORE SCATTERED. THIS ALIGNMENT IN
MODELS ONLY SEEMS TO HOLD THROUGH TUESDAY...AS MODELS SEEM TO
DISAGREE ON HOW QUICKLY THE RIDGE EXITS WEDNESDAY AND IS REPLACED BY
AN INCOMING TROUGH. ECMWF IS FASTER WITH THE FEATURE BY ABOUT 6
HOURS. FORTUNATELY...THEY DO AGREE ON THE TRACK OF THE UPPER
LOW...UNLIKE MOST OF THE PREVIOUS RUNS...SIGNALING A WET SECOND HALF
OF THE UPCOMING WEEK. SMR

&&

.HYDROLOGY...THERE IS POTENTIAL FOR HEAVY RAIN OVER THE OLYMPICS
TONIGHT WHICH MAY PUSH THE SKOKOMISH RIVER IN MASON COUNTY OVER
FLOOD STAGE. A FLOOD WATCH REMAINS IN EFFECT.

A WARM FRONT WILL STALL OVER SOUTHERN BRITISH COLUMBIA OR WESTERN WA
SUNDAY THROUGH MONDAY...POSSIBLY INTO TUESDAY. HEAVY RAIN IS
FORECAST IN THE NORTH CASCADES AND A FEW RIVERS WILL BE CLOSE TO
FLOOD STAGE. A HYDROLOGIC OUTLOOK HAS BEEN ISSUED. 33

&&

.AVIATION...STRONG WESTERLY FLOW ALOFT TODAY ON THE NORTHERN
PERIPHERY OF AN UPPER RIDGE WILL PUSH A WARM FRONT ACROSS WRN WA
TODAY AND THIS EVNG. THIS WILL RESULT IN A DEEPLY MOIST AND STABLE
AIR MASS FOR THE NEXT 24 HOURS. WIDESPREAD RAIN ALREADY REACHING THE
COAST...WITH RAIN SPREADING INLAND OVER THE NEXT FEW HOURS...THEN
PERSISTING THIS AFTN. NUMEROUS AREAS OF IFR CIGS AND REDUCED VSBY IN
RAIN WILL BE THE RESULT.

KSEA...AN INCOMING WARM FRONT WILL LEAD TO STEADY DETERIORATION IN
CIGS FROM NOW THROUGH SUNDAY MORNING. WIDESPREAD RAIN WITH THE
INCOMING FRONT WILL ARRIVE AROUND 21Z-22Z...WITH SOME REDUCTION IN
VSBY DOWN TO 5SM AT TIMES THIS AFTN. RAIN WILL EASE AFT 02Z THIS
EVNG...BUT THE CONTINUED INFLUX OF WARMER AND MOISTER AIR INTO THE
AREA WILL KEEP CIGS BELOW 020 THIS EVNG THROUGH AT LEAST SUNDAY
MORNING. HANER

&&

.MARINE...BIGGEST CHANGE WITH THE SHORT-TERM FORECAST THIS MORNING
IS TO START INLAND SMALL CRAFT ADVISORIES 6 HOURS SOONER. LOOKS LIKE
S/SE WINDS FROM ADMIRALTY INLET ON NORTH WILL BE PEAKING LATE THIS
AFTN. THE INCREASING WINDS THIS AFTN WILL PRECEDE A WARM FRONT THAT
WILL CROSS THE WATERS LATER TODAY. LOOK FOR A LULL IN THE WIND LATE
TONIGHT AND EARLY SUNDAY MORNING...THEN ANOTHER FRONT WILL CROSS THE
WATERS AND INCREASE WIND ON SUNDAY. ONSHORE GRADIENTS WILL FOLLOW
THE FRONT SUNDAY NIGHT AND CONTINUE INTO TUESDAY. A LARGE SURFACE
LOW WILL DEVELOP WELL WEST OF THE OFFSHORE WATERS TUESDAY NIGHT AND
WEDNESDAY. HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...WINTER WEATHER ADVISORY IN EFFECT UNTIL 4 AM SUNDAY FOR
 THE CASCADES OF WHATCOM AND SKAGIT COUNTIES ABOVE 3500 FEET.

     WINTER WEATHER ADVISORY IN EFFECT FROM 4 PM THIS AFTERNOON
     UNTIL 10 AM SUNDAY FOR THE CASCADES OF PIERCE AND LEWIS
     COUNTIES ABOVE 5000 FEET.

 FLOOD WATCH IN EFFECT THROUGH SUNDAY MORNING FOR MASON COUNTY.

PZ...SMALL CRAFT ADVISORY ALL WATERS.

&&

$$

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