River Flood Warning 111, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
845 AM PST TUE DEC 8 2015

.SYNOPSIS...A STRONG PACIFIC FRONTAL SYSTEM WILL BRING RAIN AND WIND
WITH HIGH SNOW LEVELS TODAY. A WAVE DEVELOPING ON THE FRONT WILL
GIVE ANOTHER ROUND OF RAIN AND WIND TO THE AREA TONIGHT. COOLER AND
SHOWERY WEATHER WILL CONTINUE WEDNESDAY THROUGH EARLY NEXT WEEK AS A
SERIES OF SYSTEMS MOVE ACROSS THE AREA.

&&

.SHORT TERM...A STRONG FRONTAL SYSTEM IS MOVING THROUGH WESTERN WA THIS
MORNING. THERE ARE WIND ADVISORIES FOR PORTIONS OF WRN WA AND A HIGH
WIND WARNING ON THE COAST AND FOR THE SAN JUANS AND WESTERN WHATCOM
COUNTY. THE STRONGEST PRESSURE FALLS HAVE SHIFTED ACROSS VANCOUVER
ISLAND AND THE PRESSURE GRADIENT WILL PEAK IN AN HOUR OR TWO ON THE
COAST AND AROUND MIDDAY FOR THE NW INTERIOR. IT IS RAINING AROUND A
QUARTER INCH AN HOUR AT PARADISE...HEAVIER RAIN THAN THAT WAS FALLING
AT SNOQUALMIE...BAKER WAS ONLY GETTING .15 TO .2 AN HOUR THIS MORNING.
AFTER THIS FIRST SURGE OF RAIN AND WIND MOVES THROUGH TODAY THERE
WILL PROBABLY BE A RELATIVE LULL BEFORE THE NEXT FRONTAL WAVE MOVES
IN TONIGHT...THERE IS A HIGH WIND WATCH UP FOR THE COAST WITH THIS
SECOND SYSTEM. WEDNESDAY WILL FEATURE STRONG ONSHORE FLOW AND SHOWERS
BEHIND THE FRONTAL SYSTEM. THEN ANOTHER STRONG FRONTAL SYSTEM ARRIVES
LATE WED NITE AND THU MORNING...THE GFS KEEPS THE DEEP MAIN PARENT LOW
WELL ENOUGH OFFSHORE BUT DEVELOPS A COMPACT 981MB SECONDARY LOW AND PUTS
THAT ON THE NORTH WA COAST BY DAYBREAK THURSDAY.

.LONG TERM...A COOL AND SHOWER AND BREEZY PERIOD IS EXPECTED FRIDAY
THROUGH EARLY NEXT WEEK AS A SERIES OF SYSTEMS MOVE THOUGH THE AREA.
NO CHANGES WERE MADE TO THE PREVIOUS LONG TERM FORECAST. ALBRECHT

&&

.AVIATION...STRONG WESTERLY FLOW WILL CONTINUE ACROSS THE PAC NW
TODAY WITH RAIN ACROSS WESTERN WA. THE AIR MASS IS MOIST AND STABLE
WITH A MIX OF CONDITIONS OVER THE AREA...WITH MAINLY VFR TO MVFR
AROUND THE SOUND AND COASTAL LOCATIONS DROPPING DOWN INTO IFR.
CORRELATING WITH CURRENT RADAR IMAGERY...IFR CONDITIONS ARE CONFINED
TO AREAS OF HEAVIEST RAINFALL. AS FORECAST IS EXPECTED TO REMAIN
FAIRLY STATIC FOR MUCH OF THE DAY...A COMBINATION OF GUSTY SOUTH
WINDS ALONG THE COAST AND INTERIOR AND RAIN CONTINUING...NOT
EXPECTING MUCH CHANGE IN CIGS TODAY AND TONIGHT. 33/SMR

KSEA...RAIN WILL CONTINUE THROUGHOUT MUCH OF THE DAY. CIGS NEAR 3000
FT BUT LOWERING TO MVFR IN MODERATE RA. SURFACE WINDS ARE FROM THE
SOUTH...GUSTING TO 30 KT THIS AFTERNOON. MAY TAPER OFF SLIGHTLY
THIS EVENING...BUT GUSTS POSSIBLE AGAIN TONIGHT. 33/SMR

&&

.MARINE...GALE FORCE WINDS ARE LIKELY OVER MUCH OF THE WATERS TODAY
AS A PASSING WARM FRONT THIS MORNING IS FOLLOWED BY A COLD FRONT
THIS AFTERNOON. WINDS WILL BRIEFLY EASE THIS EVENING...THEN INCREASE
AGAIN OVERNIGHT AS A SURFACE LOW TRACKS NORTH OVER THE COASTAL
WATERS. THIS SYSTEM WILL PUSH ANOTHER COLD FRONT INLAND EARLY
WEDNESDAY. A STRONG PACIFIC FRONTAL SYSTEM WILL IMPACT THE REGION ON
THURSDAY FOR MORE GALES AND SEAS BUILDING TO 25 TO 30 FEET.

THE TIDAL ANOMALIES CONTINUED TO RUN ABOUT 1.5 FEET. EXPECT THE
TIDES TO CONTINUE RUNNING HIGHER THAN THE PREDICTION THE NEXT
SEVERAL DAYS TO THE EFFECTS OF PERSISTENT LOW PRESSURE. A COASTAL
FLOOD WATCH MAY BE NEEDED FOR THE COAST ON THU IF THE WAVE WATCH
MODEL CONTINUES TO ADVERTISE LARGE SWELLS OF 25 TO 30 FEET REACHING
THE COAST LATE THU. 33/SMR

&&

.HYDROLOGY...ANOTHER STRONG WARM FRONT WILL MOVE THROUGH WESTERN
WASHINGTON TODAY...THE THIRD IN QUICK SUCCESSION AND THE STRONGEST
ONE IN THE SERIES. WEST-SOUTHWEST 850 MB FLOW OF 45 TO 60 KT...DEEP
MOISTURE...AND SNOW LEVELS RISING TO AROUND 8000 FT WILL BRING HEAVY
RAINFALL TO THE LOWLANDS AND ESPECIALLY THE MOUNTAINS DURING THE
NEXT 24 HOURS. ROUGHLY 3 TO 7 INCHES OF RAIN WILL FALL OVER THE
OLYMPICS AND WEST SLOPES CASCADES DURING THE NEXT 24 HOURS...WITH
LOCALLY AROUND 10 INCHES AT MOUNT RAINIER.

THE SNOW LEVEL WILL RISE TO AROUND 8000 FT TODAY...THEN FALL SLOWLY
LATE TONIGHT AND WEDNESDAY AS PRECIPITATION DECREASES. BY LATE
WEDNESDAY THE SNOW LEVEL SHOULD BE AROUND 3500 FT.

MODERATE TO MAJOR FLOODING IS LIKELY ON MOST OF OUR RIVERS. MOST
WILL REACH FLOOD STAGE LATER TODAY OR TONIGHT...THEN CREST AT THEIR
MODERATE TO MAJOR FLOOD STAGE WEDNESDAY OR WEDNESDAY NIGHT.

AS OF 8 AM FLOOD WARNINGS WERE IN EFFECT FOR THE SKOKOMISH...
SATSOP...TOLT...ELWHA...SOUTH FORK NOOKSACK...NORTH FORK STILLAGUAMISH...
STILLAGAUMISH...AND CHEHALIS RIVERS. WARNINGS FOR MANY OTHER RIVERS WILL
BE ISSUED DURING THE NEXT SEVERAL HOURS. IN ADDITION A FLOOD WATCH
IS IN EFFECT FOR OUR ENTIRE FORECAST AREA EXCEPT KITSAP...ISLAND AND
SAN JUAN COUNTIES.

IN ADDITION HEAVY RAIN OVER THE WESTERN WASHINGTON LOWLANDS --
ROUGHLY 1 TO 3 INCHES MORE IN THE INTERIOR AND 1.5 INCHES AT THE
COAST -- WILL LIKELY TRIGGER MORE LANDSLIDES. MCDONNAL

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...FLOOD WATCH FROM 6 AM PST THIS MORNING THROUGH WEDNESDAY
     AFTERNOON FOR ADMIRALTY INLET AREA-BELLEVUE AND VICINITY-
     CASCADES OF PIERCE AND LEWIS COUNTIES-CASCADES OF SNOHOMISH
     AND KING COUNTIES-CASCADES OF WHATCOM AND SKAGIT COUNTIES-
     CENTRAL COAST-EAST PUGET SOUND LOWLANDS-EASTERN STRAIT OF
     JUAN DE FUCA-EVERETT AND VICINITY-HOOD CANAL AREA-LOWER
     CHEHALIS VALLEY AREA-NORTH COAST-OLYMPICS-SEATTLE AND
     VICINITY-SOUTHWEST INTERIOR-TACOMA AREA-WESTERN SKAGIT
     COUNTY-WESTERN STRAIT OF JUAN DE FUCA-WESTERN WHATCOM
     COUNTY.

     WIND ADVISORY UNTIL 3 PM PST THIS AFTERNOON FOR ADMIRALTY INLET
     AREA-BELLEVUE AND VICINITY-BREMERTON AND VICINITY-EAST
     PUGET SOUND LOWLANDS-EVERETT AND VICINITY-HOOD CANAL AREA-
     -SEATTLE AND VICINITY-SOUTHWEST INTERIOR-
     TACOMA AREA-WESTERN SKAGIT COUNTY.

     HIGH WIND WARNING UNTIL 1 PM PST THIS AFTERNOON FOR CENTRAL
     COAST-NORTH COAST AND UNTIL 3 PM FOR THE SAN JUANS AND
     WESTERN WHATCOM COUNTY.

     HIGH WIND WATCH FROM THIS EVENING THROUGH WEDNESDAY MORNING FOR
     CENTRAL COAST-NORTH COAST.

PZ...GALE WARNINGS ALL WATERS EXCEPT CENTRAL STRAIT.

     SMALL CRAFT ADVISORY CENTRAL STRAIT.

	 SMALL CRAFT ADVISORY IN EFFECT FOR ROUGH BAR GRAYS HARBOR BAR.

&&

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