Heavy Snow in Washington, April 15 to 16, 2006

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
556 AM PDT SAT APR 15 2006

.SYNOPSIS...THE INLAND NORTHWEST WILL REMAIN COOL...WET AND
UNSETTLED THROUGH THE WEEKEND. THE WEATHER WILL TURN DRIER AND
WARMER BY THE MIDDLE OF NEXT WEEK.

&&

.DISCUSSION...
JUST MADE A QUICK UPDATE TO LOWER SNOW LEVELS IN CAMAS PRAIRIE THIS
MORNING BASED ON A SPOTTER REPORT. EXPECT MINOR ACCUMULATIONS
TODAY.

TODAY THROUGH MON...FCST FOCUS WILL BE ON SNOW ACCUMULATIONS
TONIGHT AND SUNDAY. A COLD-FRONT HAS PROGRESSED SLOWLY E OVERNIGHT,
STRETCHING N-S THRU EXTREME ERN WA AND N ID. THIS FEATURE SHOULD
NOT MOVE TOO MUCH FARTHER E TODAY GIVEN THE LACK OF WLY FLOW ALOFT.
IN FACT, THE TAIL END OF THIS FRONT WILL LIKELY STALL ACROSS
ID AND SERN WA TODAY, THEN LIFT SLOWLY NWD AS A WARM-FRONT LATER
TODAY AS THE NEXT SHORT-WAVE TROF (NOW AROUND 135W OFF THE PAC
NW COAST) MOVES ONSHORE LATE THIS AFTERNOON. BY SUNDAY MORNING,
THIS WAVE WILL ALREADY HAVE MOVED NE INTO SRN BC AND ALBERTA. SNOW
LEVELS THIS MORNING WILL FALL SLOWLY, PUTTING ACCUMULATING SNOWS
ABOVE 4K FT MSL FOR N ID FOR TODAY...AND ABOVE 2K FT MSL FOR THE E
SLOPES OF THE CASCADES IN THE UPPER REACHES OF THE LOWER VALLEYS.
HAVE ALSO PUT A COUPLE INCHES OF WET SNOW ABOVE 4K FT MSL FOR THE
CAMAS PRAIRIE OF ID FOR MAINLY TONIGHT AND SUNDAY MORNING AS POST-
FRONTAL FLOW VEERS TO THE W/NW AND STABILITY DECREASES. SNOW
HIGHLIGHTS NOT ANTICIPATED ATTM. LOOKOUT PASS WILL BE THE MAIN THREAT
AREA FOR POTENTIALLY HAZARDOUS TRAVEL. POST-FRONTAL DRY SLOT WILL
KEEP PCPN CHANGES FAIRLY LOW FOR THE COLUMBIA BASIN SUNDAY MORNING.
HOWEVER, WITH THE UPPER LOW MOVING CLOSE TO THE PAC NW COAST LATER IN
THE DAY SUNDAY, IN COMBINATION WITH INCREASED INSOLATION WITHIN THE
DRY SLOT, WEVE ADDED THE MENTION OF TSRA FOR THE NRN HALF OF ERN WA
SUNDAY. OTHER THREAT AREA FOR THUNDER WILL BE OVER THE WALLOWAS OF
NERN ORE LATE...POSSIBLY ADVECTING OFF THE HIGHER TRRN AND MOVING
INTO THE NRN BLUE MTNS AND THE CAMAS PRAIRIE. BZ

MON NIGHT THROUGH SATURDAY...THE UPPER TROUGH AXIS SHIFT THROUGH THE
REGION ON MONDAY...AND EXITS MON NITE AS A RIDGE PUMPS UP ALOFT.
THIS WILL ALLOW THE SHOWERS WILL DECREASE MONDAY NIGHT...FOLLOWED
BY PARTLY CLOUDY...DRIER AND WARMER WEATHER FOR TUESDAY
THROUGH WEDNESDAY. ANTICIPATE SOME VALLEY INVERSIONS SETTING UP
OVERNIGHT AS 850 MB TEMPS RISE FROM +2C TO +7C THROUGH THIS PERIOD
UNDER INCREASING S-SE FLOW. THE RIDGE AXIS SHIFT THROUGH THE REGION
WEDNESDAY NIGHT...LEAVING A MOISTER SW FLOW FOR THE INLAND NW WITH A
PACIFIC TROUGH RIGHT ON ITS HEELS. THE GFS AND ECWMF SHOWS A FRONT
PUSHING INLAND TO THE CASCADES ON THURSDAY...AND ACROSS ERN
WA INTO N IDAHO THURSDAY NIGHT WITH FALLING SNOW LEVELS...COOLING
TEMPERATURES BACK TO NORMAL AND A CHANCE OF RAIN AND MT SNOW. THIS
COOL AND SHOWERY PATTERN WILL LINGER THROUGH FRIDAY NIGHT WITH SOME
UPPER LEVEL RIDGING NOSING BY SATURDAY. RFOX.

&&

.AVIATION...A COLD FRONT WILL STALL OUT OVER SE WA AND THE SRN
PORTION OF ID TODAY...WHILE AN AREA OF PRECIPITATION WILL INCREASE
ALONG THE FRONT AND EVEN CAUSE THE FRONT TO BACK BUILD TO THE WEST
WITH OCCASIONAL RAIN AND HIGH MOUNTAIN WITH LOCALLY MVFR CONDITIONS.
MOUNTAIN OBSCURATIONS OVER THE BLUE AND CLEARWATER MOUNTAINS ALSO
WILL BE A FACTOR FOR MOST OF THE TODAY. CONVECTIVE ACTIVITY
WILL BEGIN TO THE NORTH OF THE FRONT IN THE LATE AFTERNOON HOURS.
CERTAINTY AS TO STRENGTH AND PLACEMENT OF CONVECTIVE ACTIVITY HINGES
ON DAYTIME HEATING AND CLOUD COVER. THEREFORE...THIS ACTIVITY WILL
BE PLAYED DOWN IN TAF AND TWEB PRODUCTS FOR NOW UNTIL CERTAINTY
INCREASES. WILL SEE MUCH OF THE CONVECTION DECREASE FROM WEST TO
EAST BETWEEN 04Z-07Z SUNDAY. /RFOX.

&&

.PRELIMINARY POINT TEMPS/POPS...
SPOKANE        48  32  45  29  48  29 /  60  70  20  20  20  10
COEUR DALENE  47  32  43  30  48  27 /  60  70  30  30  30  20
PULLMAN        49  33  43  32  48  31 / 100  70  30  30  40  20
LEWISTON       50  37  50  36  56  34 / 100  70  50  20  40  20
COLVILLE       49  30  47  23  51  28 /  60  80  50  20  20  20
SANDPOINT      49  33  45  28  49  27 /  90  90  50  30  30  20
KELLOGG        44  31  46  29  49  27 /  90  90  50  40  40  20
MOSES LAKE     53  37  53  32  56  30 /  50  40  10  20  10  10
WENATCHEE      51  36  52  36  54  35 /  60  30  30  20  10  10
OMAK           53  34  52  30  55  29 /  60  60  50  20  10  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&