Heavy Snow Warning 1, NWS Spokane, WA

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE SPOKANE WA
322 AM PST MON JAN 1 2007

.SYNOPSIS...A SERIES OF PACIFIC WEATHER SYSTEMS WILL TRACK ACROSS
THE REGION LATE TODAY THROUGH WEDNESDAY BRINGING UNSETTLED
CONDITIONS TO THE AREA.

&&

.DISCUSSION...
TODAY THROUGH TUESDAY...TRANSITION TO A MORE ACTIVE PATTERN WILL
OCCUR TODAY. INFRARED SATELLITE LOOP INDICATES AN UPPER LOW IN THE
GULF OF ALASKA...WITH A LONG FETCH OF SUBTROPICAL MOISTURE OFF THE
COAST. MODELS ARE IN GENERAL AGREEMENT THAT A WARM FRONT WILL MOVE
OVER THE AREA TONIGHT RESULTING IN ISENTROPIC LIFT OVER THE AREA.
THE BRUNT OF THE MOISTURE WILL BE AIMED ACROSS FAR NORTHERN
WASHINGTON AND BRITISH COLUMBIA. AS PRECIPITATION CROSSES THE
CASCADES LATE THIS AFTERNOON IT WILL INTERACT WITH THE COLD AIR
MASS TRAPPED IN THE LOWER LEVELS RESULTING IN PRECIPITATION
BEGINNING AS SNOW. THEN WARMER AIR WILL USHER IN A MELTING LAYER
AROUND 5000 FT MSL...WHICH WILL THEN TURN SNOW TO SLEET AND
FREEZING RAIN IN THE EAST SLOPE VALLEYS. GIVEN STRONG WESTERLY
FLOW WITH THIS SYSTEM...PRECIPITATION AMOUNTS WILL BE GENERALLY
LIGHT AWAY FROM THE CREST...BUT AREAS CLOSE TO THE CREST
ESPECIALLY IN OKANOGAN COUNTY WILL LIKELY SEE ICE ACCUMULATIONS
AROUND A QUARTER OF AN INCH. THUS THE WINTER STORM WATCH WILL BE
UPGRADED TO A WINTER STORM WARNING...WITH AGAIN AN EMPHASIS ON ICE
ACCUMULATIONS IN THOSE VALLEYS NEAR THE CREST. FURTHER EAST...A
TIGHTENING SOUTHERLY PRESSURE GRADIENT WILL SCOUR OUT THE COLD AIR
RATHER QUICKLY OVER EASTERN WASHINGTON AND IDAHO...WITH THE
FREEZING RAIN THREAT BEING RATHER BRIEF BEFORE SURFACE
TEMPERATURES RISE TO ABOVE FREEZING. OVER THE NORTHEAST
WA MOUNTAINS AND NORTHERN PANHANDLE MOUNTAINS...A COMBINATION OF STRONG
UPSLOPE FLOW AND MOISTURE WILL LEAD TO HEAVY SNOW ABOVE 4000 FEET.
WITH SOUTHERLY WINDS USHERING IN WARMER AIR IN THESE AREAS...SNOW
ACCUMULATIONS IN THE VALLEYS WILL GENERALLY RANGE FROM 1 TO 3
INCHES WITH BRIEF FREEZING RAIN POSSIBLE FOR CHANGING COMPLETELY
TO RAIN.  THUS WILL UPGRADE THE WINTER STORM WATCH TO A HEAVY SNOW
WARNING FOR THESE AREAS AS MOUNTAIN SNOW IS THE MAIN THREAT. JW

TUESDAY NIGHT AND WEDNESDAY...ACTIVE WEATHER PATTERN CONTINUES
DURING THIS PERIOD WITH A TRANSIENT STORM SYSTEM FEATURING A STRONG
SUB-TROPICAL PRECIPITABLE WATER FETCH NOSING INTO THE REGION...
ENHANCED BY A SURFACE LOW PASSAGE DURING THE DAY WEDNESDAY THROUGH
THE FORECAST AREA. FREEZING LEVELS WILL BE HIGH ENOUGH FOR
REASONABLE CONFIDENCE OF VALLEY AND BASIN RAIN WITH THIS SYSTEM...
BUT ELEVATIONS ABOVE 4000 FEET COULD SEE A 12 HOUR PERIOD OF
ACCUMULATING SNOW. ENOUGH CONFIDENCE OF THIS SCENARIO EXISTS TO
WARRANT A WINTER STORM WATCH FOR THE NORTHEASTERN MOUNTAIN ZONES
FOR AT LEAST LOW END WARNING ACCUMULATION AMOUNTS ABOVE 4000 FEET
OR SO.

WEDNESDAY NIGHT THROUGH SATURDAY...A MOIST AND PROGRESSIVE REGIME
CONTINUES THROUGH THE EXTENDED PERIOD FEATURING ANOTHER STORM
SYSTEM EVERY 36 TO 48 HOURS WITH SNOW LEVELS DECREASING WITH EACH
PASSING WAVE. PROGRESSIVE NATURE OF THE FLOW REGIME CREATES SOME
TIMING DIFFICULTIES WITH EACH PARTICULAR WAVE...BUT CONFIDENCE
INCREASING THAT EVEN VALLEY AND BASIN LOCATIONS WILL EXPERIENCE
PERIODS OF AT LEAST MINOR SNOW ACCUMULATIONS DURING THE EXTENDED
PERIOD. /FUGAZZI

&&

.AVIATION...
WIDESPREAD IFR AND LIFR CEILINGS WILL REMAIN OVER THE VALLEYS AND
COLUMBIA BASIN THROUGH 18Z...WITH MODERATE IMPROVEMENT TO MVFR
STRATUS CEILINGS AFTER 20Z MOST LOCATIONS. TOPS OF LOW LEVEL
STRATUS DECK WILL REMAIN AROUND 4000 FEET MSL THROUGH 06Z TUESDAY.
AFTER 00Z TUESDAY IN THE WEST AND AFTER 06Z IN THE EAST A WARM
FRONT WILL SPREAD INITIALLY FREEZING RAIN AND THEN RAIN OVER THE
REGION FROM SOUTH TO NORTH WITH LOW LEVEL WIND SHEAR IMPACTING THE
NORTHEASTERN TAF SITES. /MJF

&&

.PRELIMINARY POINT TEMPS/POPS...
SPOKANE        27  26  38  35  38  28 /  10  40  70  70  80  20
COEUR DALENE  28  27  39  34  39  29 /  10  50  80  70  80  20
PULLMAN        32  31  41  35  42  32 /  10  20  50  60  80  20
LEWISTON       36  33  47  39  47  32 /  10  10  20  50  70  20
COLVILLE       22  21  36  34  36  25 /  30  60  80  80  80  30
SANDPOINT      28  27  38  34  36  27 /  20  60  80  80  80  20
KELLOGG        27  26  38  33  38  27 /  10  50  80  80  80  50
MOSES LAKE     31  28  37  34  38  25 /  10  20  30  30  30  20
WENATCHEE      28  27  37  33  35  25 /  20  30  30  30  60  20
OMAK           24  23  35  32  34  25 /  20  50  50  50  80  20

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...HEAVY SNOW WARNING FROM MIDNIGHT TONIGHT TO 6 PM PST TUESDAY
     ABOVE 4000 FEET FOR NORTHERN PANHANDLE.

     WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY
     EVENING ABOVE 4000 FEET FOR NORTHERN PANHANDLE.

WA...HEAVY SNOW WARNING FROM MIDNIGHT TONIGHT TO 6 PM PST TUESDAY
     ABOVE 4000 FEET FOR NORTHEAST MOUNTAINS.

     WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY
     EVENING ABOVE 4000 FEET FOR NORTHEAST MOUNTAINS...OKANOGAN
     HIGHLANDS.

     WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO 10 AM PST
     TUESDAY FOR EAST SLOPES NORTHERN CASCADES.

&&

HAZARDOUS WEATHER OUTLOOK...CORRECTED TYPOS
NATIONAL WEATHER SERVICE SPOKANE WA
245 PM PST SUN DEC 31 2006

IDZ001-WAZ037-012245-
NORTHERN PANHANDLE-NORTHEAST MOUNTAINS-
INCLUDING THE CITIES OF...SANDPOINT...RATHDRUM...BONNERS FERRY...
PRIEST RIVER...COLVILLE...DEER PARK...CHEWELAH...NEWPORT...
KETTLE FALLS
245 PM PST SUN DEC 31 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH IDAHO
AND NORTHEAST WASHINGTON.

THE FOLLOWING WATCHES WARNINGS OR ADVISORIES ARE CURRENTLY IN EFFECT
   WINTER STORM WATCH IN EFFECT FROM MONDAY EVENING THROUGH
     TUESDAY AFTERNOON.

PLEASE SEE THE FOLLOWING PRODUCTS FOR MORE INFORMATION.
   SEAWSWOTX  /WWUS46 KOTX/

.DAY ONE...THIS AFTERNOON AND TONIGHT

PATCHY FREEZING FOG WILL CONTINUE THIS AFTERNOON AND OVERNIGHT.
OTHERWISE NO PRECIPITATION IS EXPECTED.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A POTENT WINTER WEATHER PATTERN IS SET TO DEVELOP OVER THE PACIFIC
NORTHWEST MONDAY EVENING AND LINGER THROUGH TUESDAY. THUS A WINTER
STORM WATCH IS IN EFFECT FOR THE NORTHERN PANHANDLE AND NORTHEAST
MOUNTAINS. HEAVY SNOW IS POSSIBLE IN THE VALLEYS AND MOUNTAINS
STARTING MONDAY EVENING. SNOW LEVELS WILL RISE RAPIDLY ABOVE THE
VALLEY FLOORS TUESDAY BUT HIGHER MOUNTAIN SNOW AND VALLEY RAIN WILL
CONTINUE THROUGH AT LEAST WEDNESDAY.

WAZ042-012245-
EAST SLOPES NORTHERN CASCADES-
INCLUDING THE CITIES OF...LEAVENWORTH...MAZAMA...TWISP...WINTHROP
245 PM PST SUN DEC 31 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
WASHINGTON.

THE FOLLOWING WATCHES WARNINGS OR ADVISORIES ARE CURRENTLY IN EFFECT
   WINTER STORM WATCH IN EFFECT FROM MONDAY MORNING THROUGH
     TUESDAY MORNING.

PLEASE SEE THE FOLLOWING PRODUCTS FOR MORE INFORMATION.
   SEAWSWOTX  /WWUS46 KOTX/

.DAY ONE...THIS AFTERNOON AND TONIGHT

PATCHY FREEZING FOG IN THE VALLEYS WILL CONTINUE THIS AFTERNOON
AND OVERNIGHT. OTHERWISE NO PRECIPITATION IS EXPECTED.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A POTENT WINTER WEATHER PATTERN IS SET TO DEVELOP OVER THE PACIFIC
NORTHWEST MONDAY MORNING AND LINGER THROUGH TUESDAY. THUS A WINTER
STORM WATCH IS IN EFFECT FOR THE EAST SLOPES OF THE NORTHERN CASCADE
MOUNTAINS. HEAVY SNOW IS POSSIBLE IN THE LOWER VALLEYS AND MOUNTAINS
STARTING MONDAY EVENING. SNOW LEVELS WILL RISE RAPIDLY ABOVE THE
VALLEY FLOORS TUESDAY BUT HIGHER MOUNTAIN SNOW AND VALLEY RAIN WILL
CONTINUE THROUGH AT LEAST WEDNESDAY.

WAZ038-043-012245-
OKANOGAN HIGHLANDS-OKANOGAN VALLEY-
INCLUDING THE CITIES OF...REPUBLIC...INCHELIUM...OMAK...
OKANOGAN...BREWSTER...BRIDGEPORT...OROVILLE
245 PM PST SUN DEC 31 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
WASHINGTON.

.DAY ONE...THIS AFTERNOON AND TONIGHT

PATCHY FREEZING FOG IN THE VALLEYS WILL CONTINUE THIS AFTERNOON
AND OVERNIGHT. OTHERWISE NO PRECIPITATION IS EXPECTED.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A POTENT WINTER WEATHER PATTERN IS SET TO DEVELOP OVER THE PACIFIC
NORTHWEST MONDAY. A MIXTURE OF SNOW...RAIN AND FREEZING RAIN WILL BE
POSSIBLE BETWEEN MONDAY AND TUESDAY. SNOW LEVELS WILL RISE RAPIDLY
ABOVE THE VALLEY FLOORS TUESDAY BUT HIGHER MOUNTAIN SNOW AND VALLEY
RAIN WILL CONTINUE THROUGH AT LEAST WEDNESDAY.

IDZ002>004-WAZ033>036-041-044-012245-
COEUR DALENE AREA-IDAHO PALOUSE-CENTRAL PANHANDLE MOUNTAINS-
WASHINGTON PALOUSE-MOSES LAKE AREA-UPPER COLUMBIA BASIN-
SPOKANE AREA-WENATCHEE AREA-WATERVILLE PLATEAU-
INCLUDING THE CITIES OF...COEUR DALENE...POST FALLS...HAYDEN...
MOSCOW...ST. MARIES...KELLOGG...PINEHURST...OSBURN...WALLACE...
MULLAN...PULLMAN...MOSES LAKE...EPHRATA...OTHELLO...QUINCY...
RITZVILLE...COULEE DAM...ODESSA...ELECTRIC CITY...WILBUR...
GRAND COULEE...COULEE CITY...SPOKANE...WENATCHEE...WATERVILLE...
MANSFIELD
245 PM PST SUN DEC 31 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH
IDAHO...CENTRAL WASHINGTON...EAST CENTRAL WASHINGTON...NORTH
CENTRAL WASHINGTON...NORTHEAST WASHINGTON AND SOUTHEAST
WASHINGTON.

.DAY ONE...THIS AFTERNOON AND TONIGHT

PATCHY FREEZING FOG IN THE VALLEYS WILL CONTINUE THIS AFTERNOON
AND OVERNIGHT. OTHERWISE NO PRECIPITATION IS EXPECTED.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A POTENT WINTER WEATHER PATTERN IS SET TO DEVELOP OVER THE PACIFIC
NORTHWEST MONDAY. INITIALLY...A MIXTURE OF SNOW...RAIN AND FREEZING
RAIN WILL BE POSSIBLE STARTING MONDAY AFTERNOON. SNOW AND FREEZING
RAIN ACCUMULATIONS ARE EXPECTED TO BE LIGHT...BEFORE WINTRY
PRECIPITATION BECOMES RAIN EARLY ON TUESDAY. BREEZY CONDITIONS WILL
ALSO DEVELOP TUESDAY WITH SUSTAINED WINDS 15 TO 25 MPH.