Heavy Snow in Washington, April 3, 2001

EASTERN WASHINGTON AND NORTH IDAHO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WASHINGTON
230 AM PDT TUE APR 3 2001

A COLD UPPER TROUGH CONTINUES TO LINGER THIS MORNING OVER THE
NORTHWEST WITH SEVERAL EMBEDDED VORT LOBES. SHOWERS OVER THE SOUTHERN
HALF OF THE FORECAST AREA HAVE BEEN CAUSED BY ONE VORT LOBE AND HAVE
ALREADY RECEIVED AN INCH OF SNOW HERE AT THE OFFICE. HOWEVER...MORE
ORGANIZED PRECIP WILL MOVE IN FROM THE EAST ACROSS THE NRN TIER OF
ZONES TODAY. IR SAT PIX SHOW NICELY ENHANCED CLOUDINESS SPREADING
WESTWARD FROM NRN MT INTO THE NRN ID PANHANDLE IN ASSOCIATION WITH
STRONG DIVERGENCE ALOFT. THERE IS EVEN ALREADY AN EAST-WEST SURFACE
TROUGH IN PLACE NEAR THE CANADIAN BORDER TO FURTHER HELP FOCUS
PRECIP. WITH PLENTY OF COLD AIR ALOFT...SNOW LEVELS WILL CONTINUE TO
FLIRT WITH THE VALLEY FLOORS. BELIEVE ADVISORY LEVEL SNOWFALL AMOUNTS
ARE POSSIBLE FROM THE WATERVILLE PLATEAU UP TO THE OKANOGAN VALLEY
AND ACROSS TO SANDPOINT. WILL ISSUE AN ADVISORY FOR THESE AREAS WITH
THE UPCOMING FORECAST PACKAGE. WILL CONTINUE THE MENTION OF THUNDER
IN THE FORECAST AS THE STEEPEST LAPSE RATES CONTINUE FROM THE PALOUSE
ON SOUTH.

ALL MODELS AGREE IN PUSHING DRIER AIR IN FROM THE NORTH ON WED AS THE
MAIN UPPER LOW DIGS INTO THE SW. THIS WOULD SIGNIFICANTLY CUT DOWN ON
PRECIP COVERAGE. HOWEVER...COLD AIR ALOFT AS WELL AS THE UPPER TROUGH
AXIS WILL REMAIN. HAVE LEARNED FROM PAST EXPERIENCE NOT TO TAPER POPS
OFF TOO FAST FOLLOWING THE DEPARTURE OF A COLD AND SLOW-MOVING UPPER
LOW. WILL THEREFORE KEEP SCATTERED SHOWERS GOING THROUGH WED.
HANER

IN THE EXTENDED...THE UPPER TROF AXIS FINALLY SLIDES EAST OF THE
FORECAST AREA BY LATE THURSDAY. THIS WILL PROVIDE A BREAK FROM THE
UNSETTLED WEATHER AS TEMPS REACH NEAR SEASONAL NORMALS. BUT THIS WILL
BE SHORT LIVED AS THE CONSENSUS OF THE MEDIUM RANGE MODELS SHOW MORE
SHOWERY WEATHER ON TAP FOR THE INLAND NORTHWEST. THE LATEST AVN/MRF
SHOW ANOTHER TROF NEARING THE PAC NW COAST ON FRIDAY WITH A COLD
FRONT SWEEPING THROUGH THE AREA AND REACHING NRN IDAHO BY LATE
AFTERNOON. THIS IS SLIGHTLY FASTER THAN THE PREVIOUS MODEL RUN...AND
DUE TO THE LACK OF RIDGING TO SLOW THE ARRIVAL OF THE FRONT THE
EXPECTED PATTERN...WILL ADJUST THE FORECASTS TO INCREASE THE CHANCE
OF VALLEY RAIN AND MOUNTAIN SNOW BY AFTERNOON IN ALL ZONES. THROUGH
THE WEEKEND AND INTO MONDAY...THIS TROF WILL CUT OFF AND FORM ANOTHER
COLD CLOSED LOW THAT WILL DROP ALONG THE COAST. WILL CONTINUE COOLER
TEMPS AND THE CHANCE OF RAIN AND SNOW SHOWERS THROUGH THIS PERIOD.
RLF.

...THE INFORMATION IN THIS PRODUCT CONCERNING WARNINGS AND FORECASTS
IS VALID ONLY AT THE TIME OF ISSUANCE. THE LATEST WARNING AND
FORECAST INFORMATION WILL BE FOUND IN THE APPROPRIATE PRODUCTS...

GEG 040/026/044 774
CQV 038/027/048 983
SPT 037/025/044 983
COE 039/028/044 774
WWP 036/025/041 774
LWS 047/033/050 665
PUW 040/028/044 774
EAT 0476/034/054 773
MWH 047/028/053 773

.GEG...SNOW ADVISORY TODAY AND THIS EVENING ID ZN 1 AND WA ZNS
          37/38/43 AND 44.