Flooding in Washington, December 8 to 9, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
340 PM PST TUE DEC 8 2015

.SYNOPSIS...A STRONG PACIFIC FRONTAL SYSTEM WILL CONTINUE TO BRING
RAIN TO WESTERN WASHINGTON TONIGHT. THE RAIN WILL BE HEAVY IN THE
MOUNTAINS. FLOOD WATCHES AND WARNINGS ARE IN EFFECT WITH A NUMBER OF
RIVERS ABOVE FLOOD STAGE OR LIKELY TO FLOOD. THE SNOW LEVEL WILL
FALL FROM AROUND 7000 FEET TONIGHT TO AROUND 4000 FEET LATE
WEDNESDAY AS THE RAIN TURNS TO SHOWERS. ANOTHER STRONG FRONT WILL
ARRIVE THURSDAY AND ANOTHER STRONG FRONT AND LOW PRESSURE SYSTEM
COULD AFFECT THE AREA OVER THE WEEKEND.

&&

.SHORT TERM...RAIN HAS BEEN ESPECIALLY HAVE IN THE SOUTHWEST PORTION
OF THE OLYMPICS...BUT MOST OF WRN WA HAS HAD A GOOD SOAKING TODAY.
THE NORTH AND SAN JUANS WERE NOT ESPECIALLY WET AS THE FRONTAL BAND
GOT THROUGH THERE MIDDAY...WITH THE WINDS THERE DYING DOWN AS WELL.
THE FRONTAL SYSTEM SHOULD LIFT NORTH A BIT AND SPREAD THE HEAVIER
RAIN BACK INTO NEARLY ALL OF WRN WA TONIGHT. THERE WAS A HIGH WIND
WATCH FOR THIS NEXT FRONTAL WAVE FOR THE COAST BUT I HAVE CHANGED IT
TO A WIND ADVISORY WITH JUST TYPICAL WINDY WEATHER EXPECTED TO
REDEVELOP OVERNIGHT. BUOY005 LOOKS PERFECTLY SITUATED TO SAMPLE THE
DEVELOPMENT OF THE WAVE...AS OF 3PM THE PRESSURE WAS FALLING OFF A
MILLIBAR AN HOUR BUT THE WIND WAS ONLY AROUND SW 15KT...I WOULD LIKE
TO HAVE SEEN IT BACK TO SE AND INCREASE AHEAD OF THE DEVELOPMENT.
THE SURE BET TONIGHT IS MORE RAIN AND FLOODING ON THE RIVERS...SEE
THE HYDRO SECTION BELOW FOR THAT. WEDNESDAY WILL BE A MORE SHOWERY
DAY AFTER THE FRONTAL PASSAGE...BUT STRONG ONSHORE FLOW SHOULD BE
RATHER BLUSTERY. THE SNOW LEVEL WILL GET BACK DOWN TO THE
PASSES...IT MAY TAKE AWHILE FOR SNOQUALMIE. ANOTHER STRONG FRONTAL
SYSTEM WILL ARRIVE LATER WED NITE AND THU...THE PARENT LOW LOOKS
LIKE IT WILL AGAIN MISS WRN WA BUT WINDS MIGHT BE UP IN THE WIND
ADVISORY CATEGORY AGAIN. WITH STRONG DEEP LOW PRESSURE OFFSHORE WED
NITE AND THU SEAS ALONG THE COAST SHOULD BUILD AND A COASTAL FLOOD
WATCH FOR THAT COMBINING WITH DECENT TIDAL ANOMALIES WAS ISSUED.

.LONG TERM...WE MIGHT SEE ANOTHER STRONG FRONTAL SYSTEM OVER
THE WEEKEND...THE 18Z GFS HAS AN INTERESTING 990MB LOW MOVING INTO
WESTERN WA SATURDAY AFTERNOON. ANOTHER LOW PRESSURE SYSTEM SPINS UP
SUNDAY...BUT THAT GOES ACROSS OREGON. OVERALL IT LOOKS LIKELY THAT
NEXT WEEK COULD BE COOLER AND MORE SHOWERY OVERALL...WITH MORE
SEASONABLY LOW SNOW LEVEL. THE 18Z GFS HAS A BROAD UPPER TROUGH
MOVING OVER THE REGION EARLY NEXT WEEK...FOLLOWED BY A WEAK RIDGE
AND TROUGH BY MIDWEEK...AND THEN ANOTHER COOL UPPER TROUGH DIGGING
INTO THE WEST.
THE FORECAST

&&

.AVIATION...STRONG WESTERLY FLOW WILL CONTINUE ACROSS THE PAC NW.
RAIN ASSOCIATED WITH COLD FRONT PASSAGE OVER MUCH OF WESTERN
WASHINGTON...WITH ONLY FAR NW CORNER BEHIND THE MAIN LINE. THE AIR
MASS IS MOIST AND STABLE WITH A MIX OF CONDITIONS OVER THE AREA. IFR
CONDITIONS MAINLY OVER THE SOUTH SOUND AND AT HQM...VFR TO MVFR
ELSEWHERE. THIS CORRELATES WELL WITH CURRENT RADAR IMAGERY...AS
HEAVIEST RAINFALL IS OCCURRING IN AREAS WHERE IFR IS BEING REPORTED.
FORECAST IS EXPECTED TO REMAIN FAIRLY STATIC FOR MUCH OF THE DAY AND
INTO TONIGHT...A COMBINATION OF GUSTY SOUTH WINDS ALONG THE COAST
AND INTERIOR AND RAIN CONTINUING...NOT EXPECTING MUCH CHANGE IN CIGS
TODAY AND TONIGHT. WINDS WILL TAPER OFF BRIEFLY IN THE EVENING...BUT
WILL PICK UP AGAIN DURING THE OVERNIGHT HOURS. SMR

KSEA...RAIN WILL CONTINUE FOR MUCH OF THE NEXT 24 HOURS. CIGS
GENERALLY 1.5-2K FT THIS AFTERNOON AND EVENING. MAY SEE A RISE TO 3-
5K FT TONIGHT. SURFACE WINDS ARE FROM THE SOUTH...GUSTING TO 30 KT
THIS AFTERNOON AND EARLY EVENING. MAY TAPER OFF SLIGHTLY
AFTERWARD...BUT GUSTS POSSIBLE AGAIN OVERNIGHT. SMR

&&

.MARINE...GALES MEETING WITH MIXED RESULTS AT THE TIME OF THIS
WRITING. WILL ALLOW GALES OVER INLAND WATERS TO TRANSITION TO SMALL
CRAFT ADVISORIES. CURRENT FORECAST STILL SUGGESTS GALES POSSIBLE
OVER THE COASTAL WATERS...SO WILL LEAVE THOSE GALES UP TIL 4 AM PST.
COMBINATION OF OBS AND FORECAST SOLUTIONS DOES NOT REALLY SUGGEST
ANY NEED TO EXTEND. WINDS STILL EXPECTED TO 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 WILL BE ISSUED WITH AFTERNOON FORECAST PACKAGE FOR
WESTERN WASHINGTON COAST FOR BOTH WEDNESDAY AND THURSDAY. SMR

&&

.HYDROLOGY...HEAVIEST RAIN OVER THE PAST FEW HOURS HAS BEEN POINTED
INTO SOUTHWEST WASHINGTON...BUT HOURLY RAINFALL RATES HAVE DROPPED
INTO THE ONE-TENTH TO ONE-THIRD INCH RANGE...WHICH IS NOT TERRIBLY
IMPRESSIVE. HOWEVER...APPEAR TO BE IN A RELATIVE LULL AT THIS
MOMENT. LOOKING LIKE PRECIP WILL PICK UP IN INTENSITY IN SW WA
AROUND 5-6 PM...WITH HEAVIER PRECIP THEN SPREADING NE ACROSS WRN WA
DURING THE LATE EVENING. HEAVIER RAIN RATES WILL CONTINUE IN THE
CASCADES OVERNIGHT...BEFORE TAPERING OFF ON WED MORNING.
THIS NEXT SURGE OF RAIN WILL ADD MORE WATER TO AREA RIVER SYSTEMS
AND EXACERBATE FLOODING. THE LATEST QPF...WHICH WE ISSUED AROUND 230
PM...BUMPS UP FORECAST RAINFALL FROM THE PREVIOUS FORECAST IN THE
CASCADES OF LEWIS AND PIERCE COUNTY. ALL OTHER THINGS BEING
EQUAL...THIS MIGHT BUMP LATER FORECASTS FOR THE COWLITZ RIVER UP A
LITTLE MORE. ELSEWHERE...FORECAST RAINFALL IS IN THE SAME
BALLPARK...WHICH IS GOOD FOR CONSISTENCY IN THE RIVER FORECASTS.

MANY RIVERS ARE FORECAST TO ACHIEVE MINOR OR MODERATE
FLOODING...WITH MAJOR FLOODING ON SOME OF OUR BIGGER RIVERS. MOST
RIVERS WILL CREST ON WEDNESDAY MORNING...WITH LOWER PORTIONS OF
SLOWER DRAINING RIVERS...SUCH AS THE SNOHOMISH AND
CHEHALIS...CRESTING ON WEDNESDAY NIGHT AND FRIDAY RESPECTIVELY.

SNOW LEVELS ARE RUNNING AROUND 8000 FEET RIGHT NOW. THE QUILLAYUTE
SOUNDING JUST ARRIVED WITH A FREEZING LEVEL OF 7700 FEET. SNOW
LEVELS WILL REMAIN HIGH THIS EVENING...THEN FALL TO 4000 FEET OR
LESS ON WEDNESDAY...AS PRECIPITATION IS IN THE PROCESS OF TAPERING
OFF.

IN ADDITION...HEAVY RAIN OVER THE WESTERN WASHINGTON LOWLANDS WILL
LIKELY TRIGGER MORE LANDSLIDES.		HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...FLOOD WATCHES AND NUMEROUS FLOOD WARNINGS FOR THE RIVERS OF
      WESTERN WA ARE IN EFFECT.
     COASTAL FLOOD WATCH IN EFFECT FOR NORTH COAST AND CENTRAL COAST.
     WIND ADVISORY FOR THE NORTH AND CENTRAL COAST MIDNIGHT-8AM WED.

PZ...GALE WARNINGS ALL WATERS EXCEPT CENTRAL STRAIT.
     SMALL CRAFT ADVISORY CENTRAL STRAIT.
	 SMALL CRAFT ADVISORY IN EFFECT FOR ROUGH BAR GRAYS HARBOR BAR.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
425 PM PST TUE DEC 08 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0500 PM     DEBRIS FLOW      EDMONDS                 47.83N 122.37W
12/07/2015                   SNOHOMISH          WA   BROADCAST MEDIA

            LANDSLIDE ON THE RAILROAD TRACKS FORCED THE CANCELLATION
            OF SOUNDER AND AMTRAK SERVICE BETWEEN EVERETT AND
            SEATTLE.

&&

WWW.WEATHER.GOV

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
605 PM PST TUE DEC 08 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0400 PM     HEAVY RAIN       OLALLA                  47.43N 122.54W
12/08/2015  M2.26 INCH       KITSAP             WA   TRAINED SPOTTER

            24 HOUR RAINFALL TOTAL. STILL RAINING HARD.

&&

JSMITH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
719 PM PST TUE DEC 08 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0715 PM     HEAVY RAIN       WSW GLENOMA             46.51N 122.16W
12/08/2015  M4.04 INCH       LEWIS              WA   TRAINED SPOTTER

            SINCE MIDNIGHT

&&

HANER

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
810 PM PST TUE DEC 08 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0715 PM     HEAVY RAIN       12 SW BREMERTON         47.43N 122.89W
12/08/2015  M2.59 INCH       MASON              WA   TRAINED SPOTTER

            IN PAST 24 HOURS, ENDING AT 8 PM PST

&&

HANER