900 
FXUS66 KOTX 210643
AFDOTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1043 PM PST FRI NOV 20 2009

.SYNOPSIS...
AFTER A SHORT BREAK IN THE WEATHER ON SATURDAY...A STRONGER AND
COLDER STORM SYSTEM WILL BRING THE POTENTIAL FOR MODERATE TO HEAVY
SNOWFALL MAINLY IN THE HIGH VALLEYS AND MOUNTAINS. A SERIES OF STORM
SYSTEMS WILL CONTINUE TO PASS THROUGH THE INLAND NORTHWEST EVERY
24 TO 36 HOURS WELL INTO NEXT WEEK.

&&

.DISCUSSION...
A STRONG PACIFIC SYSTEM IS EXPECTED TO IMPACT THE INLAND NORTHWEST
SATURDAY NIGHT INTO SUNDAY MORNING AND WINTER STORM WATCHES HAVE
BEEN POSTED FOR PARTS OF THE AREA. THERE CONTINUES TO BE
DISAGREEMENT FROM MODEL TO MODEL REGARDING THE TRACK AND STRENGTH
OF A SFC LOW AS IT PASSES ACROSS WASHINGTON. THE 00Z GFS MODEL IS
THE STRONGEST AND TRACKS THE LOW ALONG THE WA/BC BORDER...WHILE
THE NAM IS SLOWER AND TRACKS THE LOW FROM PORTLAND TOWARDS
PULLMAN. THE NEW 00Z CANADIAN SUPPORTS THE GFS...WHILE THE 00Z
ECMWF HAS NOT YET COME IN BUT PREVIOUS ECMWF SUPPORTED THE NAM.
DOING A MODEL INITIALIZATION OF THIS SYSTEM...THE GFS INITIALIZED
A LITTLE BIT DEEPER COMPARED TO THE 12 HR FCST FROM THE 12Z ECMWF
WHICH WAS SUPPORTED BY SHIP OBSERVATIONS. WATER VAPOR ALSO SHOWS
SOME DARKENING WITH THIS SYSTEM WITH THE LEFT EXIT PORTION OF A
JET STREAK AIDING IN INTENSIFICATION. BASED ON SATELLITE TRENDS
AND THAT THE CANADIAN BACKS UP THE GFS AND WITH THE GFS APPEARING
TO HAVE A GOOD INITIALIZATION...LEANED TOWARDS THE GFS. THE GFS
SHOWS DEEP MOISTURE AND LIFT AS A 992-995MB SFC LOW TRACKS
THROUGH THE AREA WITH QPF AMOUNTS OVER AN INCH ALONG THE CASCADE
CREST AND OVER A HALF INCH OVER THE NORTHERN HALF OF EASTERN WA/N
IDAHO. THIS LOOKS TO FALL MOSTLY IN A 12 HOUR PERIOD WITH THE BULK
OF THE PRECIPITATION FALLING SATURDAY NIGHT IN THE CASCADES AND
OVERNIGHT SATURDAY INTO SUNDAY MORNING OVER EASTERN WA/N IDAHO.
TRICKY PART IS SNOW LEVELS WITH 1000-850MB THICKNESSES 1305-1310
DM...AND 850MB TEMPS OF -2 TO -3 SNOW LEVELS LOOK TO BE NEAR 2000
FEET. THUS THE WINTER STORM WATCHES HAVE BEEN ISSUED ABOVE THIS
ELEVATION. SNOW LEVELS COULD END UP A LITTLE HIGHER AT TIMES OVER
THE SPOKANE/COEUR D'ALENE AREA AS WELL AS THE PALOUSE WITH
SOUTHERLY LOW LEVEL WINDS DEVELOPING AS THE LOW TRACKS NORTH OF
THE AREA. THUS WITH LOWER CONFIDENCE IN THESE AREAS HELD OFF ON
ANY POTENTIAL WATCHES. 

FOR TONIGHT DRIER AIR WILL CONTINUE TO MOVE INTO EASTERN
WASHINGTON BEHIND THE EARLIER COLD FRONT PASSAGE...WHILE UPSLOPE
POST FRONTAL SNOW SHOWERS FALL IN THE MOUNTAINS OF N IDAHO.
ACCUMULATIONS IN THE MOUNTAINS HOWEVER WILL ONLY RANGE FROM 1 TO 3
INCHES.  JW

&&

.AVIATION...
AREAS OF MVFR AND IFR CIGS WILL OCCUR THROUGH 18Z DUE TO ABUNDANT
LOW LEVEL MOISTURE ACROSS EASTERN WA/N IDAHO. IN THE LEE OF THE
CASCADES VFR CONDITIONS WILL PERSIST AT KEAT/KMWH AS DOWNSLOPE
FLOW HAS DRIED OUT THE LOWER LEVELS. JW

&&

.PRELIMINARY POINT TEMPS/POPS...
SPOKANE        33  39  32  37  27  39 /  20  20  90  80  10  40 
COEUR D'ALENE  33  39  31  37  28  40 /  40  20  80  70  20  50 
PULLMAN        32  39  32  36  28  42 /  50  20  70  80  20  40 
LEWISTON       36  47  36  41  30  48 /  40  10  40  90  20  30 
COLVILLE       32  40  33  40  28  38 /  10  30  80  70  10  60 
SANDPOINT      32  36  32  37  28  36 /  90  40  80  80  20  60 
KELLOGG        32  33  30  34  27  35 /  90  70  90  90  40  60 
MOSES LAKE     31  45  32  43  26  43 /   0  10  80  60   0  40 
WENATCHEE      32  43  32  43  29  41 /   0  30  90  50  10  50 
OMAK           28  43  31  42  25  40 /  10  60  90  60   0  60 

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY 
     AFTERNOON ABOVE 2500 FEET FOR CENTRAL PANHANDLE MOUNTAINS.

     WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY MORNING 
     FOR NORTHERN PANHANDLE.

WA...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY MORNING 
     FOR EAST SLOPES NORTHERN CASCADES.

     WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY MORNING 
     ABOVE 2000 FEET FOR NORTHEAST MOUNTAINS...OKANOGAN 
     HIGHLANDS.

     WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY MORNING 
     ABOVE 2000 FEET FOR OKANOGAN VALLEY...WATERVILLE PLATEAU.

&&

$$