Damaging Wind in Washington, August 26, 2004

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WASHINGTON
230 PM PDT THU AUG 26 2004

.SYNOPSIS...A GRADUAL DRYING OUT AND WARMING TREND WILL BEGIN FROM
THE WEST TO THE EAST THURSDAY NIGHT AND FRIDAY. MILD TEMPERATURES
AND DRY WEATHER WILL CONTINUE INTO THE WEEKEND.

&&

.DISCUSSION...
TONIGHT THROUGH SATURDAY...A WEAKENING UPPER LEVEL TROUGH OVER NE WA
IS STILL UNSTABLE ENOUGH TO PRODUCE SHOWERS AND ISOLATED
THUNDERSTORMS FOR MAINLY EASTERN WASHINGTON AND THE IDAHO PANHANDLE.
SHOWER AND THUNDERSTORMS WILL BE FAIRLY WEAK BUT STILL BEARS WATCHING
FOR LIGHTNING POTENTIAL BETWEEN I-90 NEAR SPOKANE NORTHWARD TO THE
CANADIAN BORDER THIS EVENING. SHOWERS WILL GRADUALLY FADE TONIGHT AS
AN UPPER LEVEL RIDGE PUSHES IN FROM THE WEST.

THE RIDGE WILL SQUASH ANY SHOWER POTENTIAL EXCEPT FOR THE BITTERROOT
MOUNTAINS OF IDAHO LATE MORNING AND AFTERNOON.  THE HIGH PRESSURE
RIDGE WILL BE FAIRLY FLAT WITH MOISTURE STREAMING THROUGH CANADA AND
A SHORTWAVE TROUGH MOVING THROUGH B.C. ON SATURDAY. THE ETA IS
FARTHER NORTH THAN THE GFS WITH THE GFS PUTTING LIGHT PRECIPITATION
FOR SATURDAY ALONG THE CANADIAN BORDER.  HAVE SIDED WITH THIS
SOLUTION AND KEPT SLIGHT CHANCE POPS FAR NORTH OF THE FORECAST
AREA. GENERALLY THERE WILL BE A DRYING AND WARMING TREND FRIDAY AND
SATURDAY.

SATURDAY NIGHT THROUGH THURSDAY...THE PERIOD WILL START OFF WITH THE
INLAND NW JUST SOUTH OF A STRONG ZONAL JET OVER SOUTHERN BC.
PROXIMITY OF JET WILL LIKELY SPREAD PLENTY OF MID/HIGH LEVEL CLOUD
COVER OVER THE NORTHERN HALF OF THE CWA. ALSO CANNOT RULE OUT A WEAK
SHORTWAVE PASSING THROUGH THE JET AND BRINGING SOME LIGHT SHOWERS
TO THE FAR NORTHERN ZONES. BY SUNDAY NIGHT AND MONDAY THE FLOW
BEGINS TO BUCKLE AS STRONG HEIGHT FALLS DROP INSIDE OF 135W. THIS
WILL PUSH THE JET INTO CENTRAL BC AND TURN THE FLOW SW OVER OUR
CWA AND SHOULD RESULT IN DECENT WARMING. BY TUESDAY THE TROF BEGINS
TO MIGRATE EASTWARD...AN IDEA NOW SHARED AMONGST ALL EXTENDED
MODELS. THIS WILL RESULT IN THE EASTWARD SHIFT OF A MOISTURE LADEN
FRONTAL BOUNDARY...WITH SHOWERS REACHING THE CASCADE CREST FIRST
AND THEN GRADUALLY SAGGING SE ACROSS THE ENTIRE CWA BY LATE
TUESDAY.  BY WEDNESDAY AND THURSDAY...THE UPPER LEVEL TROF MOVES
INLAND WITH 500 MB TEMPS PLUNGING TO -22C OR COOLER...OR ABOUT 4C
COOLER THAN THE CURRENT TROF. THE RESULTANT POTENTIAL INSTABILITY
COULD PRODUCE SOME THUNDERSTORMS AS 850-500 MB LAPSE RATES PLUMMET.
NOT CERTAIN THE AIRMASS WILL BE THIS UNSTABLE...BUT SHOWERS LOOK
LIKE A GOOD POSSIBILITY. TEMPERATURES WILL FALL BELOW NORMAL
VALUES ONCE AGAIN BY MIDWEEK. FX

&&

.PRELIMINARY POINT TEMPS/POPS...

SPOKANE        049 074 048 078 051 078/ 50 05 00 05 10 05
COEUR DALENE  048 073 048 077 049 077/ 50 05 00 05 10 10
PULLMAN        048 070 048 078 050 080/ 50 05 00 00 05 05
LEWISTON       053 078 052 083 056 087/ 50 05 00 00 05 05
COLVILLE       046 077 046 078 048 077/ 50 10 05 20 20 10
SANDPOINT      046 072 046 072 048 077/ 60 10 05 10 20 10
WALLACE        045 068 047 068 051 076/ 60 30 00 10 05 10
MOSES LAKE     052 080 050 082 053 086/ 20 00 00 00 05 05
WENATCHEE      053 081 053 082 057 084/ 20 00 00 00 10 10
OMAK           046 080 048 081 051 083/ 20 00 00 00 10 10
&&

.OTX...
ID...NONE.
WA...NONE.