Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 121145
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
345 AM PST FRI FEB 12 2016

.SYNOPSIS...A WEAK COLD FRONT WILL PASS THROUGH WESTERN WASHINGTON
THIS MORNING. AN UPPER LEVEL TROUGH WILL PRODUCE SHOWERS THIS
AFTERNOON THROUGH SATURDAY MORNING. A PAIR OF WARM FRONTS WILL BRING
RAIN SATURDAY AFTERNOON THROUGH SUNDAY EVENING. WEST FLOW ALOFT WILL
MAINTAIN AN ACTIVE WEATHER PATTERN INTO EARLY NEXT WEEK.

&&

.SHORT TERM...RAIN ASSOCIATED WITH THE WARM FRONT THAT PASSED
THROUGH THE AREA YESTERDAY STILL LINGERING...ALBEIT SCATTERED. MAIN
FOCUS FOR TODAY WILL BE WHETHER OR NOT COLD FRONT WILL GAIN STRENGTH
AS IT GETS CLOSER TO WASHINGTON COAST AS MODELS PREDICT. A GOOD VOTE
IN FAVOR OF THIS HAPPENING IS THAT SOME DEVELOPMENT IS STARTING TO
OCCUR ALONG THE WEST COAST OF VANCOUVER ISLAND...SO FEEL SAFE WITH
POPS FOR THE MORNING. IN THE WAKE OF THIS FRONT...AN UPPER LEVEL
TROF IS PROGGED TO MOVE INTO THE AREA BY THIS EVENING AND PASS
THROUGH WESTERN WA...CROSSING EAST OF THE CASCADES BY SATURDAY
MORNING...KEEPING SHOWERS IN THE FORECAST IN THE WAKE OF THE
AFOREMENTIONED COLD FRONT.

THE PAIR OF WARM FRONTS FOR THE REMAINDER OF THE WEEKEND POSE A BIT
OF A CONCERN...WITH THE POTENTIAL FOR HEAVY RAIN ESPECIALLY ALONG
THE COAST...EARLY SATURDAY EVENING AND ON THE WEST SLOPES OF THE
CASCADES SATURDAY NIGHT. CURRENT FORECAST SHOWS QPF AROUND AN INCH
FOR A LARGE PORTION OF THE OLYMPIC PENINSULA...WHICH MAY GIVE RISE
TO SOME HYDRO CONCERNS. QPF AMOUNTS DO DIMINISH RATHER QUICKLY
STARTING SUNDAY...WHICH MAY HELP TO OFFSET THOSE CONCERNS...BUT THE
RISK OF PRECIP WILL LINGER FOR THE REMAINDER OF SUNDAY.

FLAT UPPER LEVEL RIDGING MAY BRING A BRIEF PAUSE IN PRECIP FOR
MONDAY...ALTHOUGH GFS IS A BIT MORE OPTIMISTIC THAN ECMWF.
STILL...WAS HAPPY FOR ANY CHANCE TO DROP POPS BACK INTO CHANCE
CATEGORY.

SNOW LEVELS GENERALLY REMAINING HIGH FOR THE SHORT TERM...ALTHOUGH
WILL FALL STARTING TONIGHT AND REACHING THEIR NADIR AROUND 3500 FT
SATURDAY BEFORE REBOUNDING SATURDAY NIGHT. THIS TREND IS ALSO
APPLICABLE TO TEMPS...AS SATURDAY LOOKS TO BE THE COOLEST WITH
LOWLAND HIGHS AROUND 50...THEN BOUNCING BACK TO MID 50S SUNDAY AND
MONDAY.

MODELS REMAIN IN FAIR AGREEMENT FOR THE SHORT TERM...ASIDE FROM
DISAGREEMENT REGARDING MONDAY PREVIOUSLY MENTIONED...THUS NO MAJOR
CHANGES TO THE FORECAST. SMR

.LONG TERM...MONDAY ONLY PROVES TO BE THE START OF THE DIVERGENCE IN
THE MODELS. STARTING TUESDAY...IT LOOKS LIKE DOMINANT WEATHER
FACTORS WILL BE A PAIR OF LOWS OUT OVER THE PACIFIC...ONE PROGGED TO
GO NORTH OF WESTERN WA INTO CANADA...THE OTHER...WELL...THAT DEPENDS
ON WHICH MODEL TO BELIEVE. AND EVEN THEN...GFS AND ECMWF HAVE TRADED
SOLUTIONS IN THE PAST 24 HOURS. GFS NOW FAVORS WETTER SOLUTION WITH
SOUTHERN LOW COMING ON SHORE OFF THE OREGON COAST WHILE ECMWF NOW
HAS LOW GOING INTO CALIFORNIA...WHICH WOULD KEEP THE CWA NOT
ENTIRELY DRY...BUT PRECIP WOULD BE MORE SCATTERED. NEEDLESS TO
SAY...THIS DOES NOT PUT A GREAT DEAL OF CONFIDENCE IN THE EXTENDED.
THUS...LIKE PREVIOUS DAYSHIFT...HAVE OPTED FOR BROAD BRUSH POPS OVER
THE AREA UNTIL A SOLUTION GELS BETWEEN THE TWO. SMR

&&

.HYDROLOGY...RIVER FLOODING IS UNLIKELY THROUGH SATURDAY. THERE IS
SOME POTENTIAL FOR HEAVY RAIN OVER THE OLYMPICS AND NORTH CASCADES
BEGINNING SATURDAY NIGHT WHICH COULD CAUSE THE SKOKOMISH RIVER AND
POSSIBLY A FEW RIVERS IN THE NORTH CASCADES TO FLOOD EARLY NEXT WEEK.

&&

.AVIATION...MOIST SOUTHWESTERLY FLOW ALOFT CONTINUING TODAY. AIR
MASS STABLE BECOMING SLIGHTLY UNSTABLE BEHIND COLD FRONT LATER THIS
MORNING.

COLD FRONT MOVING THROUGH THIS MORNING. WIDE VARIETY OF CEILINGS
AHEAD OF THE COLD FRONT RANGING FROM NEAR 200 FEET UP TO AROUND 5000 FEET.
CEILINGS GENERALLY SETTLING IN THE 1000-2000 FOOT RANGE MID MORNING.
IMPROVING CEILINGS BEHIND THE COLD FRONT THIS AFTERNOON BACK UP INTO THE
4000-5000 FOOT RANGE EXCEPT NEAR KPAE WHERE A CONVERGENCE ZONE IN THE VICINITY
WILL KEEP CEILINGS MVFR. LITTLE CHANGE THROUGH THE EVENING HOURS.

KSEA...CEILINGS NEAR 2000 FEET THROUGH LATE MORNING WITH BRIEF CEILINGS NEAR
500 FEET AND VISIBILITIES 2-4SM IN LIGHT RAIN. CEILINGS IMPROVING TO
4000-5000 FEET THIS AFTERNOON INTO THE EVENING HOURS. SOUTHEAST WIND 6 TO 10 KNOTS
BECOMING SOUTHERLY 10-15 KNOTS LATE MORNING. FELTON

&&

.MARINE...COLD FRONT MOVING THROUGH THE WATERS THIS MORNING WITH SMALL CRAFT
ADVISORY SOUTHERLY WINDS ALONG THE COAST...AT THE ENTRANCES TO THE STRAIT...
ADMIRALTY INLET AND THE NORTHERN INLAND WATERS. POST FRONTAL ONSHORE FLOW
THIS AFTERNOON INTO SATURDAY. SMALL CRAFT ADVISORY SOUTHERLY WINDS
OVER PUGET SOUND AND HOOD CANAL WILL DEVELOP THIS AFTERNOON AND CONTINUE INTO
SATURDAY.

A SERIES OF FRONTAL SYSTEMS WILL GIVE SMALL CRAFT ADVISORY CONDITIONS TO MOST
OF THE WATERS SAT NIGHT THROUGH EARLY NEXT WEEK. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY ALL WATERS.

     SMALL CRAFT ADVISORY FOR ROUGH BAR THROUGH SATURDAY FOR
     GRAYS HARBOR BAR.
&&

$$

WWW.WEATHER.GOV/SEATTLE

AN ILLUSTRATED VERSION OF THIS FORECAST DISCUSSION CAN BE SEEN AT
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