Heavy Snow in Washington, November 14 to 15, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
930 AM PST SAT NOV 14 2015

.SYNOPSIS...A FRONT WILL REMAIN OVER WESTERN WASHINGTON THROUGH
TONIGHT WITH RAIN CONTINUING OVER THE AREA. AN APPROACHING UPPER
LEVEL TROUGH WILL PUSH THE FRONT EAST SUNDAY MORNING WITH RAIN
CHANGING TO SHOWERS. A WARM FRONT WILL BRING RAIN BACK TO THE AREA
MONDAY AND TUESDAY...FOLLOWED BY A COLD FRONT ON WEDNESDAY. COOLER
NORTHWEST FLOW ALOFT WILL BRING A FEW SHOWERS AFTER MID WEEK.

&&

.SHORT TERM...IR AND WV SATELLITE IMAGERY INDICATE A COMPLEX LOW
PRESSURE SYSTEM DEVELOPING AS IT APPROACHES THE PAC NW/NRN CA. THE
MAIN 1005 MB SURFACE LOW IS OUT NEAR 130W/40N BUT STRONG BAROCLINICITY
OUT AHEAD OF THE LOW IS DRAPED ACROSS CENTRAL WRN WA THIS MORNING.
SNOW WILL BE HEAVY AT TIMES NORTH OF THE FRONTAL BAND WITH SNOW
LEVELS DOWN TO 4000 FEET THROUGH TONIGHT. THE NORTH CASCADES AND
OLYMPICS SHOULD EASILY GET SNOW AMOUNTS IN EXCESS OF A FOOT AND
PERHAPS LOCALLY 2+ FEET ALONG THE NORTH SLOPES INCLUDING SPOTS LIKE
HURRICANE RIDGE. RAIN WILL BE HEAVY AT TIMES TO THE SOUTH OF THE
FRONT OVER THE CENTRAL/SOUTH CASCADES AND THE LOWLANDS WITH SNOW
LEVELS OVER 7000 FEET. SATELLITE IMAGERY SHOWS THE UPPER TROUGH IS
BECOMING MORE N/S ORIENTED AND MODELS INDICATE THE FRONT WILL LIFT
NORTH WITH SNOW CHANGING OVER TO RAIN IN THE CENTRAL PASSES WHERE IT
IS CURRENTLY SNOWING. IT DOES APPEAR THE NORTH CASCADE ZONES AND
OLYMPICS STAY ALL SNOW AND THE WINTER STORM WARNING WAS UPDATED TO
BEGIN NOW AND ALSO INCREASE LOCALLY HEAVY SNOW AMOUNTS. THE LOWLANDS
COULD GET ANOTHER 1-2 INCHES THROUGH TONIGHT ON TOP OF THE HALF TO
LOCALLY 2+ INCHES THAT HAS GENERALLY FALLEN OVERNIGHT. INTERIOR
LOWLAND RAIN AMOUNTS WILL GENERALLY BE LOWER TO THE NORTH AND HIGHER
SOUTH...ESPECIALLY ACROSS LEWIS AND THURSTON COUNTIES.

THE SURFACE LOW WILL BECOME ELONGATED AS IT DEVELOPS AND MOVES
INLAND SUNDAY MORNING. THIS WILL TILT THE PRECIPITATION AXIS MORE
N/S OVER WRN WA AS IS PUSHES EAST OF THE CASCADES. SNOW
LEVELS WILL CRASH DOWN TO 2000 FEET BEHIND THE FRONT ON SUNDAY AND
LOCALLY DOWN TO 1000 FEET. SUNDAY WILL GENERALLY BE A
COOLER...SHOWERY...AND BLUSTERY DAY. PRECIPITATION WILL
LIGHT WITH PERHAPS LOCALLY 1 OR 2 INCHES FALLING AT LOWER PASS
LEVELS SUCH AS SNOQUALMIE PASS. A PUGET SOUND CONVERGENCE ZONE MAY
DEVELOP DURING THE AFTERNOON AND POSSIBLY CONTINUE THROUGH SUNDAY
NIGHT IF THE 4KM WRFGFS IS CORRECT. THE NORTH SEATTLE TO EVERETT
CORRIDOR COULD GET SOME ADDITIONAL RAINFALL OVERNIGHT. THIS COULD
ALSO TRANSLATE TO LOCALLY A COUPLE INCHES OF SNOW IN THE CASCADES OF
NORTHERN KING AND SNOHOMISH COUNTIES.

MUCH OF WRN WA WILL HAVE A BREAK IN THE PRECIPITATION LATER SUNDAY
NIGHT AND MONDAY MORNING. THE NEXT WARM FRONTAL SYSTEM WILL ARRIVE
MONDAY AFTERNOON WITH MORE RAIN DEVELOPING ACROSS WRN WA. IT COULD
BE LOCALLY WINDY BEHIND THE WARM FRONT AS WELL...ESPECIALLY COAST
AND NORTH INTERIOR. THIS WILL ONLY BE A PRECURSOR TO ANOTHER VERY WET
SYSTEM TO IMPACT THE REGION. SEE THE UPDATED HYDROLOGY SECTION BELOW
FOR MORE DETAILS. MERCER

.LONG TERM...FROM 300 AM DISCUSSION...THE GFS AND ECMWF ARE IN
AGREEMENT...AT LEAST FOR NOW...THAT ANOTHER PERIOD OF VERY MOIST W
FLOW ALOFT MAY OCCUR EARLY NEXT WEEK. AFTER A WARM FRONT BRINGS THE
INITIAL SURGE OF RAIN ON MONDAY...THE GFS HAS STRONG MOIST W FLOW
ALOFT CONTINUING THROUGH TUESDAY NIGHT. RAIN WILL PROBABLY BE HEAVY
OVER THE MOUNTAINS AND WOULD EVENTUALLY SHUT OFF WEDNESDAY MORNING AS
A COLD FRONT MOVES S ACROSS THE AREA. THE ECMWF IS A LITTLE FASTER
WITH THE COLD FRONT...BRINGING IT ACROSS THE AREA BY TUESDAY EVENING.
AT THIS POINT THIS EVENT DOES NOT LOOK NEARLY AS WET AS THE CURRENT
ONE...ONLY DROPPING 5-7 INCHES OF RAIN. HOWEVER THE BREAK SUNDAY AND
SUNDAY NIGHT DOES NOT ALLOW MUCH TIME FOR RIVERS TO RECEDE.

&&

.HYDROLOGY...STEVENS PASS IS BARELY ABOVE FREEZING AND HAS BEEN
GETTING SNOW WHILE AREAS SOUTH ARE WARMER AND ARE GETTING AT LEAST
MODERATE RAIN. THE FOCUS OF RAINFALL WILL SHIFT TO THE SOUTHWEST
INTERIOR THIS AFTERNOON AND THIS EVENING WITH FLOODING CONCERNS ALSO
MIGRATING SOUTH. IT APPEARS THE COWLITZ RIVER NEAR RANDLE WILL CREST
JUST ABOVE FLOOD STAGE AND A WARNING IS OUT FOR THAT. THE CHEHALIS
AND OTHER SOUTHWEST INTERIOR RIVERS WILL RISE TODAY AND MAY
HAVE MINOR FLOODING.

RIVERS NORTH OF THE SNOQUALMIE WILL CREST TODAY OR HAVE CRESTED
ALREADY. THE SNOQUALMIE IS PAUSING IN ITS RECESSION AND MAY HAVE
ANOTHER MINOR RISE. SOUTH OF THERE THE RIVERS ARE STILL RISING. ANY
NEW FLOODING NOW IS LIKELY TO BE MINOR AND WILL LIKELY END OVERNIGHT
OR EARLY SUNDAY.

OF MORE CONCERN IS THE NEXT WEATHER SYSTEM DUE AROUND TUESDAY.
MODELS ARE IN ROUGH AGREEMENT THAT THIS WILL BE ANOTHER WARM AND WET
FLOOD PRODUCER. OVER ABOUT 36 HOURS THROUGH AROUND WEDNESDAY
AFTERNOON RAINFALL TOTALS ARE ANOTHER 5-8 INCHES IN THE MOUNTAINS
GENERALLY WITH SOME 10-13 INCH BULLSEYES. RIVERS WILL BARELY HAVE
HAD ENOUGH TIME TO FALL BELOW FLOOD STAGE IN THE 48 HOURS OR SO
BETWEEN SYSTEMS. RUNOFF IS LIKELY TO BE HIGH AND MANY RIVERS COULD
FLOOD AGAIN...POSSIBLY HIGHER THAN THE CURRENT FLOOD. BURKE

&&

.AVIATION...SOUTHWEST FLOW ALOFT. A STATIONARY FRONT SITS FROM
THE CENTRAL WASHINGTON CASCADES SW TO THE NORTH OREGON COAST. A LOW
PRES SYSTEM DEVELOPING OFF THE CENTRAL OREGON COAST WILL MOVE NE
ALONG THE FRONT AND DEEPEN TO 995 MB AS IT MOVES ACROSS THE SOUTHERN
PUGET SOUND EARLY SUNDAY MORNING...THEN NE INTO SOUTH CENTRAL
BRITISH COLUMBIA SUNDAY. THE AIR MASS IS MOIST AND STABLE.

EXPECT MVFR WITH LOCAL IFR CONDITIONS IN RAIN THROUGH TONIGHT.
CONDITIONS WILL SLOWLY IMPROVE FROM THE WEST AND NORTHWEST SUNDAY
MORNING. ALBRECHT

KSEA...EXPECT CIGS TO DROP TO OVC015 BY 20Z AND CONTINUE 010-015
THROUGH 14Z SUNDAY. VIS WILL FALL TO 2-4 SM IN LIGHT TO OCCASIONALLY
MODERATE RAIN. LIGHT NORTH WINDS WILL LIKELY INCREASE TO 8 KT OR
GREATER AFTER 08Z AND FURTHER INCREASE TO 10-15 KT AFTER 05Z WITH
WIND SHIFTING TO THE SOUTHWEST ABOUT 14Z SUNDAY. ALBRECHT

&&

.MARINE...A STATIONARY FRONT EXTENDS FROM ABOUT THE MOUTH OF THE
COLUMBIA SOUTHWESTWARD THIS MORNING. A DEVELOPING 1005 MB LOW IN THE
CENTRAL OREGON OFFSHORE WATERS WILL LIFT NE TO THE PUGET SOUND AREA
EARLY SUNDAY MORNING. EXPECT SMALL CRAFT ADVISORY NORTH TO NORTHWEST
WINDS TO DEVELOP OVER THE COASTAL WATERS...AND ALL OF THE INLAND
WATERS EXCEPT FOR THE CENTRAL STRAIT OF JUAN DE FUCA...THIS EVENING
THROUGH EARLY SUNDAY MORNING AS THE LOW DEVELOPS AND MOVES INTO THE
PUGET SOUND AREA. THE LOW IS NOT EXPECTED TO DEVELOP AS MUCH AS
EARLIER THOUGHT...SO THE GALE WARNING FOR THE COASTAL WATERS WAS
CHANGED TO A SMALL CRAFT ADVISORY.

AS THE LOW MOVES OFF TO THE NORTHEAST ON SUNDAY...EXPECT SMALL CRAFT
ADVISORY WESTERLY WINDS TO DEVELOP OVER THE CENTRAL STRAIT OF JUAN
DE FUCA.

A STRONG WARM FRONT WILL MOVE THROUGH THE WATERS ON MONDAY. THIS
FRONT WILL LIKELY PRODUCE GALE FORCE WINDS OVER THE COASTAL WATERS
AND IN THE INLAND WATERS EXCEPT FOR PUGET SOUND AND HOOD CANAL. TO
THE SOUTH OF THE WARM FRONT...STRONG SOUTH TO SOUTHWEST FLOW WILL
CONTINUE WITH GALES POSSIBLE ALL WATERS. WINDS WILL BECOME NORTHWEST
BUT REMAIN RATHER STRONG WEDNESDAY AS THE FRONT MOVES SOUTH AS A
COLD FRONT.

WAVE MODELS ARE NOW SHOWING THE DEVELOPMENT OF A 20-25 FT SEA WITH
PERIODS AROUND 14 SECONDS TUESDAY MORNING AND CONTINUING INTO
TUESDAY NIGHT. THESE WAVES WILL LIKELY RESULT IN ANOTHER PERIOD OF
BEACH EROSION ON THE WASHINGTON COAST...ESPECIALLY AROUND THE BEACH
DAMAGED AREA IN OCEAN SHORES.  ALBRECHT

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...WINTER STORM WARNING FOR THE OLYMPICS AND NORTH CASCADES.
	 FLOOD WARNINGS/WATCHES ARE IN EFFECT FOR MUCH OF THE CWA.

PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS WASHINGTON COAST TODAY.

     SMALL CRAFT ADVISORY ALL WATERS EXCEPT FOR THE CENTRAL STRAIT
     OF JUAN DE FUCA THIS EVENING THROUGH SUNDAY MORNING.

     SMALL CRAFT ADVISORY GRAYS HARBOR BAR FOR ROUGH BAR CONDITIONS.

&&

WWW.WEATHER.GOV/SEATTLE

AN ILLUSTRATED VERSION OF THIS FORECAST DISCUSSION CAN BE SEEN AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
656 AM PST SAT NOV 14 2015

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

0655 AM     HEAVY RAIN       4 NNW EATONVILLE        46.93N 122.30W
11/14/2015  M2.03 INCH       PIERCE             WA   TRAINED SPOTTER

&&