Winter Storm Warning 14, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
400 AM PST SAT NOV 29 2014

.SYNOPSIS...THE CONVERGENCE ZONE OVER THE NORTHERN PUGET SOUND AREA
WILL CONTINUE TO PRODUCE SHOW SHOWERS THEN SHIFT SOUTH AS MODIFIED
ARCTIC AIR PUSHES THROUGH THE AREA BY LATE MORNING. WEAK HIGH
PRESSURE ALOFT AND LOW LEVEL OFFSHORE FLOW WILL KEEP COOL AND DRY
CONDITIONS OVER THE REGION SUNDAY INTO EARLY NEXT WEEK. A SYSTEM
MOVING INTO OREGON WEDNESDAY WILL BRING A CHANCE OF SHOWERS
WEDNESDAY.

&&

.SHORT TERM...THE CONVERGENCE ZONE THAT DEVELOPED OVERNIGHT OVER THE
NORTH PUGET SOUND AREA HAS PRODUCED 2 TO 3 INCHES OF SNOW OVER PARTS
OF SNOHOMISH COUNTY. SNOW FALL OVER THE NORTH INTERIOR HAS TAPERED
OF AS CONDITIONS HAVE GENERALLY DRIED OVER WESTERN WHATCOM AND
SKAGIT COUNTIES WITH THE COLD AIR PUSHING IN FROM THE FRASER. WINDY
CONDITIONS WITH THE OUTFLOW WILL CONTINUE TO DEVELOP OVER WESTERN
WHATCOM AND SAN JUAN COUNTIES THIS MORNING WITH NORTH WINDS 20 TO 30
MPH GUSTING TO 50 MPH. EXPECT WINDS TO EASE DURING THE LATE
AFTERNOON.

MESOSCALE MODELS CONTINUE TO SHOW THE CONVERGENCE ZONE SHIFT SOUTH
THROUGH THE MORNING AS THE MODIFIED ARCTIC AIR PUSHES THROUGH THE
REMAINDER OF THE INTERIOR. MANY LOCATIONS COULD SEE UP TO AN INCH OF
SNOW AS THE BOUNDARY SHIFTS SOUTH. IN ADDITION...THE UPPER LEVEL LOW
WILL ALSO TRACK OVER WESTERN WASHINGTON THIS MORNING WHICH COULD
ALSO BOOST PRECIP. EXPECT DRYING AND MUCH COOLER CONDITIONS NORTH OF
THE BOUNDARY WITH HIGH TEMPERATURES NOT EXPECTED TO RISE ABOVE
THE MID 30S THROUGH MUCH OF THE WESTERN WASHINGTON LOWLANDS.
CLEARING TONIGHT AND COLD AIR WILL HELP LOW TEMPERATURES DROP DOWN
INTO THE TEENS AND 20S BY SUNDAY MORNING WITH THE COLDEST
TEMPERATURES OVER THE NORTH INTERIOR. EXPECT SUNNY SKIES SUNDAY WITH
HIGH TEMPERATURES IN THE MID 30S.

THE UPPER LEVEL RIDGE OVER THE NE PACIFIC WILL PRODUCE COLD NW FLOW
ALOFT OVER WESTERN WASHINGTON MONDAY WHILE A SYSTEM OFF THE NORTHERN
CALIFORNIA COAST BRINGS WARM AND MOIST AIR INTO OREGON. THE FORECAST
CONTINUES TO HIGHLIGHT A CHANCE OF RAIN OVER SOUTH INTERIOR MONDAY
WITH INCREASING CLOUDS.

.LONG TERM...MEDIUM RANGE MODELS CONTINUE TO SHOW GENERALLY DRY
CONDITIONS INTO MIDWEEK FOLLOWED BY RAIN SPREADING NORTHWARD AS A
PACIFIC SYSTEM MOVES INTO NORTHER CALIFORNIA AND OREGON WEDNESDAY.
THE TRACK AND TIMING OF THIS TRANSITION DIFFER SOMEWHAT WITH THE
ECMWF BRINGING THE SYSTEM FURTHER NORTH INTO OREGON THAN THE GFS.
THE CURRENT FORECAST REFLECTS THE WETTER SOLUTION WEDNESDAY THROUGH
FRIDAY.

&&

.HYDROLOGY...PRECIPITATION OVER THE MOUNTAINS HAS TURNED TO SNOW AS
COLD AIR MOVES SOUTH INTO THE AREA. NO ADDITIONAL HYDROLOGICALLY
SIGNIFICANT PRECIPITATION IS EXPECTED FOR THE NEXT SEVERAL DAYS.
WITH THE EXCEPTION TO THE LOWER REACHES OF THE SKAGIT RIVER...RIVERS
HAVE CRESTED OR ARE CRESTING EARLY THIS MORNING AND WILL RECEDE FOR
THE NEXT SEVERAL DAYS.

FOR THE RIVERS THAT ARE NOW FLOODING FROM NORTH TO SOUTH...

THE SKAGIT RIVER NEAR CONCRETE CRESTED ABOUT 6 PM FRIDAY EVENING
JUST ABOVE THE MAJOR FLOOD STAGE AND IS NOW RECEDING. THE RIVER WILL
FALL BELOW FLOOD STAGE AT CONCRETE MIDDAY TODAY. AT MOUNT
VERNON...THE RIVER IS STILL RISING. IT APPEARS THAT THE SKAGIT AT
MOUNT VERNON WILL CREST JUST BELOW THE MAJOR FLOOD STAGE OF 32 FEET
EARLY THIS AFTERNOON THEN FALL BELOW FLOOD STAGE AFTER MIDNIGHT
TONIGHT.

THE SKOKOMISH RIVER AT GOLD BAR FELL BELOW FLOOD STAGE EARLY THIS
MORNING AND WILL FALL BELOW FLOOD STAGE DOWNSTREAM FROM THE GOLD BAR
GAGE THIS MORNING. THE SNOHOMISH RIVER NEAR MONROE CRESTED
OVERNIGHT AND WILL FALL BELOW FLOOD STAGE THIS MORNING. THE
SNOHOMISH AT SNOHOMISH APPEARS TO BE CRESTING EARLY THIS MORNING AT
MODERATE FLOOD STAGE AND WILL FALL BELOW FLOOD STAGE EARLY THIS
EVENING.

THE SNOQUALMIE RIVER AT CARNATION IS CRESTING EARLY THIS MORNING AND
WILL FALL BELOW FLOOD STAGE BY EARLY THIS AFTERNOON.

THE SKOKOMISH RIVER CRESTED LATE FRIDAY AFTERNOON. IT IS ONLY VERY
SLOWLY FALLING AND MAY STAY ABOVE FLOOD STAGE INTO MIDDAY SUNDAY.
ALBRECHT

&&

.AVIATION...MOIST WESTERLY FLOW ALOFT WILL CONTINUE THIS MORNING.
EXPECT GUSTY NE WINDS AT KBLI DUE TO FRASER RIVER OUTFLOW. LOWLAND
SNOW IS POSSIBLE THIS MORNING AS A COOL UPPER LEVEL TROUGH CROSSES
OVERHEAD. SNOW WILL TAPER OFF 18-21Z FROM NORTH TO SOUTH AS THIS
TROUGH EXITS AND PRECIP SHIFTS TO THE CASCADES. THE AIR MASS WILL
REMAIN COOL AND DRY TONIGHT WITH NORTHERLY FLOW. 33

KSEA...A COOL AND UNSETTLED AIR MASS WILL BRING SNOW SHOWERS TO THE
TERMINAL THIS MORNING. SNOWFALL AMOUNTS OF AN INCH OR LESS POSSIBLE.
THE BEST TIMEFRAME WILL BE 13-19Z AS A CONVERGENCE ZONE SHIFTS SOUTH
THROUGH KING COUNTY. SURFACE WINDS WILL ALSO SWITCH TO NORTHERLY
WITH SURFACE TEMPS NEAR FREEZING. DRIER WEATHER IS FORECAST BY 21Z.
33

&&

.MARINE...FRASER RIVER OUTFLOW WILL BRING NORTHERLY GALES TO THE
NORTHERN INLAND WATERS TODAY...WITH SMALL CRAFT ADVISORY WINDS OVER
THE REMAINING WATERS. FRASER OUTFLOW WILL EASE THIS EVENING. HIGH
PRES EAST OF THE CASCADES WILL MAINTAIN OFFSHORE FLOW ACROSS WESTERN
WA THROUGH EARLY NEXT WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WATCHES AND WARNINGS IN EFFECT FOR PORTIONS OF
      WESTERN WASHINGTON.
     WIND ADVISORY WESTERN WHATCOM...AND SAN JUAN COUNTY.
     WINTER WEATHER ADVISORY NORTH PUGET SOUND REGION AND STRAIT OF
     JUAN DE FUCA.

PZ...GALE WARNING NORTHERN INLAND WATERS.
     SMALL CRAFT ADVISORY ALL REMAINING WATERS.
     SMALL CRAFT ADVISORY GRAYS HARBOR BAR FOR ROUGH BAR CONDITIONS.

&&

WWW.WEATHER.GOV/SEATTLE

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
121 AM PST SAT NOV 29 2014

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

0117 AM     SNOW             5 ESE MARYSVILLE        48.03N 122.06W
11/29/2014  M1.4 INCH        SNOHOMISH          WA   TRAINED SPOTTER

            1.4 INCHES MEASURED IN LAKE STEVENS AT 255 FEET.

0117 AM     SNOW             5 S EVERETT             47.89N 122.21W
11/29/2014  M1.0 INCH        SNOHOMISH          WA   TRAINED SPOTTER

            ONE INCH OF SNOW.

0117 AM     SLEET            1 NE REDMOND            47.69N 122.10W
11/29/2014  E0.00 INCH       KING               WA   TRAINED SPOTTER

            HAIL, SLEET, OR SNOW PELLETS. ABOUT 1/4 INCH DIAMETER.

&&

JNEHER