River Flood Warning 64, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 AM PST TUE DEC 9 2014

.SYNOPSIS...A SERIES OF VIGOROUS FRONTAL SYSTEMS WILL BRING RAINY
AND WINDY WEATHER TO WESTERN WASHINGTON THROUGH THURSDAY. THERE WILL
BE HEAVY RAIN AT TIMES...ESPECIALLY IN THE OLYMPICS AND NORTH
CASCADES. COOLER AND DRIER WEATHER WILL ARRIVE THIS WEEKEND.

&&

.SHORT TERM...THE FIRST OF SEVERAL VIGOROUS FRONTAL SYSTEMS IS
MOVING THROUGH THE REGION EARLY THIS MORNING. THIS FEATURE HAS
BROUGHT RAIN TO ALL OF WESTERN WASHINGTON...WITH AMOUNTS OF 2 TO 4
INCHES FAIRLY COMMON OVER THE OLYMPIC COAST AND OLYMPIC
MOUNTAINS...1 TO 2 INCHES AROUND MOUNT BAKER...AND GENERALLY UP TO 1
INCH ELSEWHERE. WINDS WERE GUSTING INTO THE INTO THE 30 TO 55 MPH
RANGE ALONG THE COAST AND NORTHWEST INTERIOR AT 2 AM...AS RAIN
CONTINUED OVER MOST OF THE FORECAST AREA. THE SNOW LEVEL IS AROUND
7000 FT...AND 2 AM TEMPERATURES WERE MAINLY IN THE 50S.

THIS FIRST FRONTAL SYSTEM WILL CONTINUE MOVING NORTHEAST THROUGH THE
AREA THIS MORNING...WITH PRECIPITATION AND WINDS GENERALLY
DECREASING LATER TODAY AND THIS EVENING. THE WIND ADVISORY FOR THE
COAST AND NORTHWEST INTERIOR WILL REMAIN IN EFFECT THROUGH NOON
TODAY.

RAIN WILL INCREASE AGAIN TONIGHT AS THE WARM FRONT OF THE NEXT
FRONTAL SYSTEM MOVES IN FROM THE SOUTHWEST. ITS COLD FRONT WILL MOVE
THROUGH LATE WEDNESDAY. THAT FEATURE WILL PRODUCE ANOTHER PERIOD OF
SIGNIFICANT PRECIPITATION WITH THE SNOW LEVEL AROUND 7000 FT. WE CAN
EXPECT ANOTHER 2 TO 5 INCHES OVER THE OLYMPIC MOUNTAINS...AND
ANOTHER 1 TO 3 INCHES OVER THE CASCADES WITH THE HEAVIEST AMOUNTS
AROUND MOUNT BAKER. IN ADDITION...MODELS SHOW SLIGHTLY STRONGER
WINDS WITH THIS SYSTEM...AGAIN MAINLY AT THE COAST AND IN THE
NORTHWEST INTERIOR. A HIGH WIND WATCH IS IN EFFECT FOR POSSIBLE
SUSTAINED WINDS TO 40 MPH AND GUSTS TO 65 MPH.

A THIRD FRONTAL SYSTEM WILL MOVE THROUGH LATE WEDNESDAY NIGHT AND
THURSDAY. THIS FEATURE WILL PRODUCE LESS PRECIPITATION -- MAYBE JUST
ANOTHER 1 TO 2 INCHES IN THE OLYMPICS AND CASCADES -- BUT IT POSES A
GREATER THREAT OF HIGH WINDS. THE GFS AND UW WRF-GFS RUNS HAVE BEEN
FAIRLY CONSISTING IN SHOWING A SURFACE LOW TRACKING QUICKLY
NORTH-NORTHWEST ACROSS THE OREGON COASTAL WATERS AND WESTERN
WASHINGTON ON THURSDAY. THE OTHER MODELS ARE SIMILAR BUT SOMEWHAT
WEAKER AND SLOWER. IF THE GFS HAS IT MORE OR LESS CORRECT...THEN WE
COULD HAVE SOME HIGH WINDS THROUGHOUT THE WESTERN WASHINGTON
LOWLANDS.   MCDONNAL

.LONG TERM...A MUCH MORE BENIGN PATTERN WILL PREVAIL DURING THE
EXTENDED FORECAST PERIOD FRIDAY THROUGH MONDAY. THE UPPER TROUGH
ASSOCIATED WITH THE THURSDAY FRONTAL SYSTEM WILL MOVE THROUGH ON
FRIDAY. IT WILL BRING SOME SHOWERS WITH THE SNOW LEVEL AROUND 4000
FT. A WEAK UPPER RIDGE WILL MOVE THROUGH ON SATURDAY...THEN PROGRESS
EAST OF THE CASCADES ON SUNDAY AS A WEAK AND SPLITTING SYSTEM
APPROACHES THE AREA FROM THE WEST. THAT WEAK FRONT SHOULD MOVE
INLAND ON MONDAY.   MCDONNAL

&&

.HYDROLOGY...A VERY WET PATTERN WITH HIGH SNOW LEVELS WILL PREVAIL
THROUGH WEDNESDAY...POSING A THREAT OF FLOODING FOR MOST OF OUR
FORECAST AREA. A FLOOD WATCH IS IN EFFECT FOR MUCH OF THE FORECAST
AREA...AND THE FORECAST RAINFALL AMOUNTS COULD RESULT IN MAJOR
FLOODING ON SOME RIVERS. A FLOOD WARNING IS IN EFFECT FOR THE
SKOKOMISH RIVER. ADDITIONAL FLOOD WARNINGS COULD BE ISSUED LATER
THIS MORNING FOR OTHER OLYMPIC PENINSULA RIVERS.

THE FIRST OF SEVERAL VIGOROUS FRONTAL SYSTEMS MOVING THROUGH THE
REGION HAS BROUGHT 2 TO 4 INCHES OF RAIN TO THE OLYMPIC COAST AND
OLYMPIC MOUNTAINS...1 TO 2 INCHES AROUND MOUNT BAKER...AND GENERALLY
UP TO 1 INCH ELSEWHERE IN THE CASCADES. THERE WILL PROBABLY BE
ANOTHER 1 TO 2.5 INCHES IN THE OLYMPICS AND CASCADES TODAY AS THIS
FEATURE LIFTS NORTHEAST OF THE AREA. THE NEXT SYSTEM WILL BRING
ANOTHER 2 TO 5 INCHES OVER THE OLYMPIC MOUNTAINS...AND ANOTHER 1 TO
3 INCHES OVER THE CASCADES WITH THE HEAVIEST AMOUNTS AROUND MOUNT
BAKER. THE SNOW LEVEL WILL BE IN THE 7000 TO 8000 FT RANGE THROUGH
THE PERIOD.   MCDONNAL

&&

.AVIATION...A STRONG FRONT WILL MOVE THROUGH THE AREA THIS MORNING
WITH STRONG SOUTHWESTERLY FLOW ALOFT. AIR MASS STABLE AND MOIST.
STRONG WARM FRONT MOVING UP FROM THE SOUTH MOVING INTO THE AREA
TONIGHT WITH THE TRAILING COLD FRONT ARRIVING ON WEDNESDAY. STRONG
SOUTHWESTERLY FLOW ALOFT CONTINUING INTO WEDNESDAY.

CEILINGS OVER THE INTERIOR IN THE 3500-5000 FOOT RANGE EARLY THIS
MORNING WITH LOWER CEILINGS...NEAR 2000 FEET ALONG THE COAST. STRONG
FRONT MOVING THROUGH LATER THIS MORNING WITH CEILINGS LOWERING OVER
THE INTERIOR INTO 1500-2500 FOOT RANGE WITH AND BEHIND THE FRONT.
CEILINGS IMPROVING LATE AFTERNOON INTO THE EVENING HOURS BACK UP TO
4000-6000 FEET AS A WARM FRONT APPROACHES FROM THE SOUTH.

STRONG SOUTHERLY FLOW ALOFT WITH WINDS AT 2000 TO 3000 FEET...
50-60 KNOTS...UNTIL THE FRONTAL PASSAGE GIVING AREAS OF LLWS.
FELTON

KSEA...CEILINGS NEAR 5000 FEET LOWERING TO NEAR 2500 WITH AND BEHIND
THE FRONT LATE TUESDAY MORNING INTO TUESDAY AFTERNOON. CEILINGS
IMPROVING TONIGHT BACK UP TO NEAR 5000 FEET. SOUTHEAST WIND 8-12
KNOTS BECOMING SOUTH 15-20 KNOTS WITH GUSTS 25-30 KNOTS LATE MORNING
INTO THE AFTERNOON HOURS. WINDS ALOFT AT 2000-3000 FEET SOUTH
SOUTHWESTERLY 50-55 KT UNTIL AROUND 20Z GIVING LLWS. FELTON

&&

.MARINE...A STRONG FRONT OVER THE COASTAL WATERS WILL MOVE INLAND
LATER THIS MORNING. THIS FRONT WILL BE FOLLOWED BY AN EVEN STRONGER
ONE LATE TONIGHT INTO WEDNESDAY. EACH OF THESE FRONTS WILL BRING
STORM FORCE WINDS TO THE COASTAL WATERS AND GALE FORCE WINDS TO THE
NORTH INLAND WATERS...EAST ENTRANCE AND ADMIRALTY INLET. GALE FORCE
SOUTHERLY WINDS ARE POSSIBLE WEDNESDAY OVER PUGET SOUND AND HOOD
CANAL AS THE SECOND FRONT MOVES INLAND.

FOR THURSDAY THE MODELS ARE HAVING A HARD TIME COMING UP WITH A
CONSISTENT SOLUTION. THE GENERAL IDEA IS THAT A SURFACE LOW WILL
MOVE UP FROM THE SOUTH THROUGH THE AREA MIDDAY THURSDAY INTO
THURSDAY EVENING. THE GFS MODEL IS THE STRONGEST AND FASTEST MODEL
WITH THIS FEATURE BRINGING GALE FORCE WINDS TO ALL OF THE WATERS
THURSDAY AFTERNOON. THE ECMWF MODEL IS SLOWER AND WEAKER WITH THE
LOW WITH POSSIBLE GALE FORCE WINDS. THE EARLY MORNING FORECAST
PACKAGE LEANS TOWARD THE GFS SOLUTION. STAY TUNED.

COMBINED SEAS OVER THE COASTAL WATERS IN THE 18 TO 24 FOOT RANGE
WILL CONTINUE INTO WEDNESDAY WITH THE HIGHEST SEAS OVER THE OUTER
COASTAL WATERS.

WINDS WILL BECOME LIGHT FRIDAY INTO SATURDAY WITH HIGH PRESSURE
BUILDING OVER THE WATERS. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...FLOOD WATCH/WARNINGS IN EFFECT.
     WIND ADVISORY NORTH AND CENTRAL COAST...NORTHWEST INTERIOR
       THROUGH NOON TODAY.
     COASTAL FLOOD ADVISORY FOR LOW LYING AREAS ALONG THE INLAND
       WATERS THROUGH NOON TODAY.
      HIGH WIND WATCH NORTH AND CENTRAL COAST...NORTHWEST INTERIOR
        THIS EVENING THROUGH WEDNESDAY AFTERNOON.
PZ...STORM WARNING COAST.
     GALE WARNING ENTRANCES TO THE STRAIT...CAMANO ISLAND TO POINT
     ROBERTS AND ADMIRALTY INLET.
     SMALL CRAFT ADVISORY PUGET SOUND AND HOOD CANAL AND CENTRAL
     STRAIT OF JUAN DE FUCA.
     SMALL CRAFT ADVISORY FOR ROUGH TO SEVERE GRAYS HARBOR BAR.

&&

YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML