River Flood Warning 69, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
328 AM PST TUE NOV 17 2015

.SYNOPSIS...A DEEPENING FRONTAL SYSTEM WILL BRING RAIN AND VERY
WINDY CONDITIONS TO WESTERN WASHINGTON TODAY...WITH POSSIBLE
FLOODING AS WELL. COOL SHOWERY WEATHER WILL FOLLOW ON WEDNESDAY
AND A WEAKER SYSTEM WILL MOVE THROUGH OREGON WEDNESDAY NIGHT AND
THURSDAY. DRY WEATHER IS LIKELY FRIDAY...AND ADDITIONAL WEAK
FRONTAL SYSTEMS COULD BRING SOME RAIN OVER THE WEEKEND.

&&

.SHORT TERM...A WARM FRONT HAS BEEN MOVING INTO WESTERN WASHINGTON
DURING THE NIGHT...AND IT IS AT THE LEADING EDGE OF A DEEP FETCH
OF MOISTURE EXTENDING OFFSHORE BEYOND 140W. TEMPERATURES HAD RISEN
INTO THE MID 40S TO MID 50S AT 2 AM IN AREAS BEHIND THE WARM
FRONT -- BASICALLY THE COAST...SOUTH INTERIOR...AND SOUTH PART OF
THE PUGET SOUND REGION -- WHILE AREAS NORTH OF THE WARM FRONT WERE
STILL IN THE MID 30S TO MID 40S. 24 HOUR RAINFALL AMOUNTS OF 1 TO
2 INCHES WERE COMMON...AND LOCALLY UP TO 3 INCHES...ALONG THE
COAST AND LOWER CHEHALIS BASIN. GENERALLY 6 TO 12 INCHES OF SNOW
FELL IN THE MOUNTAINS.

THE WARM FRONT WILL MOVE ACROSS THE CASCADES DURING THE NEXT FEW
HOURS. THIS WILL CAUSE TEMPERATURES IN THE MOUNTAINS TO RISE
FURTHER...WITH THE SNOW LEVEL CLIMBING TO 6500 TO 7000 FT THIS
MORNING AND PRECIPITATION AT THE MOUNTAIN HIGHWAY ELEVATIONS
CHANGING TO RAIN. THERE WILL BE A BIT MORE SNOW THIS MORNING AS
THIS HAPPENS...BUT WE WILL LET THE WINTER STORM WARNING EXPIRE ON
SCHEDULE AT 4 AM.

A 160 KT WEST-EAST JET ALONG 50N IS CAUSING A FRONTAL WAVE TO
DEVELOP OFFSHORE...AND THE RESULT WILL BE A SURFACE LOW DEEPENING
AS IT MOVES QUICKLY EAST ACROSS SOUTHERN BRITISH COLUMBIA TODAY --
PROBABLY TO AROUND 986 MB OVER SOUTHWEST BRITISH COLUMBIA THIS
MORNING AND 980 MB AS IT CROSSES THE CANADIAN ROCKIES LATE TODAY.
THIS FEATURE SHOULD PRODUCE VERY WINDY CONDITIONS ACROSS MUCH OF
THE WESTERN WASHINGTON LOWLANDS TODAY WITH THE SOUTHERLIES...AND
CONTINUING WITH THE WESTERLIES THIS EVENING OVER THE LAND AREAS
ADJACENT TO THE EASTERN STRAIT OF JUAN DE FUCA. WE MADE SOME MINOR
ADJUSTMENTS TO THE WIND WARNINGS...MAINLY TO DELAY THE START TIME
TILL 8 AM THIS MORNING AND THE DOWNGRADE THE WARNING FOR THE LOWER
CHEHALIS VALLEY TO AN ADVISORY. IN THE ZONES WITH A WARNING...
THERE SHOULD BE AREAS OF 20 TO 40 MPH SUSTAINED WINDS WITH GUSTS
TO 60 MPH.

THE COLD FRONT WILL EXTEND SOUTHWEST FROM THE SURFACE LOW...MOVING
ACROSS WESTERN WASHINGTON LATE THIS MORNING AND AFTERNOON.
PRECIPITATION WILL BECOME SHOWERY IN THE NORTHWEST FLOW BEHIND
THE FRONT TONIGHT...AND A PUGET SOUND CONVERGENCE ZONE SHOULD
DEVELOP. THE SNOW LEVEL WILL FALL TO AROUND 2500 FT TONIGHT AS
PRECIPITATION TAPERS OFF IN THE MOUNTAINS...WITH UP TO ANOTHER 6
INCHES OF SNOW ON MOUNTAIN HIGHWAYS AND PASSES. COOL MOIST
NORTHWEST FLOW WILL CONTINUE WEDNESDAY WITH SOME SHOWERS...MAINLY
OVER THE MOUNTAINS.

FOR MORE DISCUSSION ON PRECIPITATION AMOUNTS AND POTENTIAL FLOOD
IMPACTS...SEE THE HYDROLOGY SECTION BELOW.

ANOTHER WEAKER FRONTAL SYSTEM WILL MOVE INTO THE PACIFIC NORTHWEST
OFFSHORE WATERS LATE WEDNESDAY NIGHT AND INLAND ON THURSDAY. ITS
SURFACE LOW WILL LIKELY TRACK ACROSS OREGON...AND MOST OF THE
PRECIPITATION WITH IT WILL BE OVER THE SOUTHERN HALF OF OUR
FORECAST AREA. THE SNOW LEVEL WILL STAY AROUND 2000 FT. MCDONNAL

.LONG TERM...MODELS AGREE THAT A MINOR UPPER RIDGE WILL MOVE
ACROSS THE AREA FRIDAY...AND THERE IS REASONABLE CONFIDENCE THAT
IT WILL BE A DRY AND PARTLY SUNNY DAY. SURFACE HIGH PRESSURE OVER
SOUTHERN BRITISH COLUMBIA SHOULD PRODUCE OFFSHORE FLOW AND LIMIT
FOG AS WELL. MODEL SOLUTIONS DIVERGE PRETTY BADLY BEYOND FRIDAY.
THE LATEST GFS SOLUTION SHOWS ESSENTIALLY DRY WEATHER THIS WEEKEND
AND MONDAY...BUT THERE HAS BEEN LITTLE CONSISTENCY FROM ONE RUN
TO THE NEXT. IT LOOKS LIKE RATHER WEAK SYSTEMS COULD MOVE THROUGH
THE AREA OVER THE WEEKEND OR EARLY NEXT WEEK...AND WE WILL KEEP A
CHANCE OF RAIN IN THE FORECAST FOR NOW. MCDONNAL

&&

.AVIATION...A WARM FRONT WILL BE OVER THE AREA TODAY WITH STRONG
WEST FLOW ALOFT. A DEEP SURFACE LOW WILL TRACK INLAND ACROSS
SOUTHERN BRITISH COLUMBIA TODAY. A COLD FRONT WILL PUSH ONSHORE
LATE TODAY. ONSHORE FLOW WILL EASE TONIGHT. AIR MASS MOIST AND
STABLE.

KSEA...LOW CLOUDS AND OCCASIONAL REDUCED VISIBILITIES WILL PREVAIL
TODAY. SOUTH WIND 10 TO 15 KNOTS WILL INCREASE TO 20 TO 30 KNOTS
WITH GUSTS TO 45 KNOTS POSSIBLE BY THIS AFTERNOON. WINDS WILL
EASE AND TURN MORE WESTERLY TONIGHT AND CEILINGS SHOULD IMPROVE A
BIT. SCHNEIDER

&&

.MARINE...A DEEP SURFACE LOW WILL MOVE INLAND OVER BRITISH
COLUMBIA TODAY. THIS WILL BRING GALES TO ALL WATERS WITH STORM
FORCE WINDS POSSIBLE ENTRANCES TO THE STRAIT. STORM FORCE WEST
WINDS WILL LIKELY DEVELOP IN THE STRAIT THIS AFTERNOON AND EVENING AS
THE LOW MOVES INLAND. 19 TO 22 FOOT WEST SWELL WILL MOVE INTO THE
COASTAL WATERS LATER TODAY...THEN SUBSIDE ON WEDNESDAY

LIGHTER ONSHORE FLOW WILL PREVAIL WEDNESDAY. A WARM FRONT WILL
MOVE THROUGH THE SOUTH PART OF THE WATERS WEDNESDAY NIGHT AND
THURSDAY WITH A FILLING SURFACE LOW MOVING INTO OREGON THURSDAY.
NORTHERLY OFFSHORE FLOW WILL DEVELOP THURSDAY AND FRIDAY AS HIGH
PRESSURE MOVES OVER SOUTHERN BRITISH COLUMBIA. SCHNEIDER

&&

.HYDROLOGY...WARM AIR HAS BEEN SLOW TO MOVE INTO THE AREA
OVERNIGHT. TEMPERATURES IN THE PASSES HAVE FINALLY GONE ABOVE
FREEZING IN THE LAST COUPLE OF HOURS. THE TEMPERATURES AT
MOUNT BAKER REMAIN BELOW FREEZING. BECAUSE OF THIS
PRECIPITATION IN THE MOUNTAINS OVERNIGHT HAS BEEN MOSTLY SNOW
THROUGH 11Z.

PRECIPITATION AMOUNTS PICKING UP IN THE LAST COUPLE OF HOURS
WITH SNOQUALMIE PASS REPORTING NEARLY AN INCH OF WATER BETWEEN
MIDNIGHT AND 2 AM. SINCE 00Z (4 PM) PRECIPITATION AMOUNTS HAVE
RANGED FROM ABOUT 0.75 INCHES TO 1.75 INCHES IN THE CASCADES WITH
THE HIGHEST AMOUNTS NEAR SNOQUALMIE PASS. IN THE OLYMPICS SINCE
00Z PRECIPITATION AMOUNTS ALONG THE SOUTH SLOPES ARE GENERALLY IN
THE 1 TO 1.5 INCH RANGE WITH LOWER TOTALS ALONG THE WESTERN SLOPES
AND IN THE NORTHERN AREAS.

HEAVY RAIN WILL CONTINUE OVER THE MOUNTAINS WITH ANOTHER 3
TO 6 INCHES FORECASTED FOR THE OLYMPICS AND CASCADES IN THE NEXT 18
HOURS. PRECIPITATION RATES WILL SIGNIFICANTLY DECREASE TONIGHT. IN
ADDITION COOLER AIR WILL MOVE INTO THE AREA.

SOME RIVERS HAVE ONLY RECENTLY FALLEN BELOW FLOOD STAGE FROM THE
LAST HEAVY RAIN EVENT OVER THE WEEKEND. THEY WILL STILL BE RUNNING
HIGH WHEN RUNOFF FROM THIS SYSTEM BEGINS TO ENTER THE RIVERS. THE
GROUND WILL STILL BE SATURATED AND RUNOFF IS LIKELY TO BE FASTER
THAN USUAL. MANY RIVERS COULD FLOOD AND SOME RIVERS COULD RISE TO
HIGHER LEVELS THAN THEY DID DURING THE RECENT FLOOD. THIS COMBINED
WITH THE HEAVY RAIN WILL CAUSE FAST SHARP RISES LATER TODAY INTO
TONIGHT. A FLOOD WARNING IS ALREADY IN EFFECT FOR THE SKOKOMISH
RIVER. FLOOD WARNINGS ARE LIKELY FOR MOST OF THE MAIN STEM RIVERS
FLOWING OFF THE THE CASCADES FROM THE NOOKSACK TO THE SNOQUALMIE BY
LATE THIS AFTERNOON AS WELL AS MOST RIVERS FLOWING OFF THE
OLYMPICS. FLOOD WARNINGS ARE POSSIBLE BY LATE THIS AFTERNOON FOR THE
RIVERS SOUTH OF THE SNOQUALMIE TO THE COWLITZ. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...HIGH WIND WARNING FROM 5 AM EARLY THIS MORNING TO 6 PM PST THIS
     EVENING FOR BELLEVUE AND VICINITY-BREMERTON AND VICINITY-
     EAST PUGET SOUND LOWLANDS-HOOD CANAL AREA-SEATTLE AND
     VICINITY-TACOMA AREA.

     FLOOD WATCH THROUGH LATE WEDNESDAY NIGHT 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.

     WINTER STORM WARNING UNTIL 4 AM PST EARLY THIS MORNING FOR
     CASCADES OF PIERCE AND LEWIS COUNTIES-CASCADES OF SNOHOMISH
     AND KING COUNTIES-CASCADES OF WHATCOM AND SKAGIT COUNTIES.

     WIND ADVISORY UNTIL 6 PM PST THIS EVENING FOR SAN JUAN COUNTY-
     WESTERN SKAGIT COUNTY-WESTERN WHATCOM COUNTY.

     HIGH WIND WARNING FROM 7 AM THIS MORNING TO 6 PM PST THIS
     EVENING FOR CENTRAL COAST-LOWER CHEHALIS VALLEY AREA-NORTH
     COAST-WESTERN STRAIT OF JUAN DE FUCA.

     HIGH SURF ADVISORY FROM NOON TODAY TO MIDNIGHT PST TONIGHT FOR
     CENTRAL COAST-NORTH COAST.

     WIND ADVISORY FROM 5 AM EARLY THIS MORNING TO 6 PM PST THIS
     EVENING FOR SOUTHWEST INTERIOR.

     HIGH WIND WARNING FROM 5 AM EARLY THIS MORNING TO 9 PM PST THIS
     EVENING FOR EVERETT AND VICINITY.

     HIGH WIND WARNING FROM 5 AM EARLY THIS MORNING TO MIDNIGHT PST
     TONIGHT FOR ADMIRALTY INLET AREA.

     HIGH WIND WARNING FROM 7 AM THIS MORNING TO MIDNIGHT PST TONIGHT
     FOR EASTERN STRAIT OF JUAN DE FUCA.

PZ...SMALL CRAFT ADVISORY FOR ROUGH BAR UNTIL 1 AM PST WEDNESDAY FOR
     GRAYS HARBOR BAR.

     GALE WARNING UNTIL 10 PM PST THIS EVENING FOR COASTAL WATERS
     FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-COASTAL
     WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM-COASTAL
     WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10 TO 60 NM-
     COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE OUT 10
     NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER
     10 TO 60 NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE
     SHOALWATER OUT 10 NM-NORTHERN INLAND WATERS INCLUDING THE
     SAN JUAN ISLANDS.

     STORM WARNING FROM 10 AM THIS MORNING TO 10 PM PST THIS EVENING
     FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST
     ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.

     GALE WARNING UNTIL 7 AM PST THIS MORNING FOR EAST ENTRANCE U.S.
     WATERS STRAIT OF JUAN DE FUCA.

     STORM WARNING UNTIL 4 PM PST THIS AFTERNOON FOR WEST ENTRANCE
     U.S. WATERS STRAIT OF JUAN DE FUCA.

     GALE WARNING UNTIL 4 AM PST EARLY THIS MORNING FOR WEST ENTRANCE
     U.S. WATERS STRAIT OF JUAN DE FUCA.

     SMALL CRAFT ADVISORY UNTIL 4 AM PST EARLY THIS MORNING FOR
     CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-PUGET SOUND AND
     HOOD CANAL.

     GALE WARNING UNTIL 7 PM PST THIS EVENING FOR ADMIRALTY INLET.

     GALE WARNING UNTIL 7 PM PST THIS EVENING FOR PUGET SOUND AND
     HOOD CANAL.

&&

WWW.WEATHER.GOV/SEATTLE

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
807 AM PST TUE NOV 17 2015

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

0806 AM     HEAVY RAIN       1 E MARBLEMOUNT         48.53N 121.43W
11/17/2015  M2.60 INCH       SKAGIT             WA   TRAINED SPOTTER

            RAINFALL IN PAST 24 HOURS AS OF 8 AM.

&&

GRUB