474
FXUS66 KOTX 152333 AAA
AFDOTX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SPOKANE WA
433 PM PDT THU MAY 15 2008
SYNOPSIS
DRY AND INCREASINGLY WARM CONDITIONS WILL PREVAIL OVER THE INLAND
NORTHWEST THROUGH THE WEEKEND...WITH NEAR RECORD HIGH TEMPERATURES
AND POSSIBLE RIVER FLOODING EXPECTED BY SATURDAY AS MOUNTAIN SNOW
MELTS OFF AT AN ACCELERATED RATE.
DISCUSSION
UPDATED AVIATION DISCUSSION.
TONIGHT THROUGH SUNDAY...LONGWAVE RIDGE PARKED OVER THE PACIFIC
NORTHWEST AMPLIFIES WITH TIME THROUGH THIS FORECAST PERIOD
ALLOWING FOR A SUBSTANTIAL WARMING TREND COUPLED WITH A DRY
FORECAST. FLOOD WATCH WILL BE ISSUED TO ADDRESS THE INCREASED
SNOW MELT AFFECT ON AREA RIVERS AND STREAMS. A SUBTLE CHANGE TO
MONITOR IN THIS SCENARIO WILL BE HOW THE LOW LEVEL THERMAL RIDGE
AT 850MB MIGRATES FROM THE COAST AND OVER THE CASCADES TO NORTHWEST
MONTANA...TIMING NOW SUGGESTS THE THERMAL RIDGE WILL BE ON THE
WEST SIDE AND OVER THE CASCADES FRIDAY...THEN MOVES OVER TO
EASTERN WASHINGTON AND NORTHERN IDAHO SATURDAY...AND SUNDAY VIA TWO
MINI MARINE PUSHES INTO THE WEST SIDE WITH THE STRONGER MARINE
PUSH SHOWING UP SUNDAY WITH ENOUGH STRENGTH TO INCREASE SKY COVER
SOME AND ALLOW FOR INCREASED WIND WITH MINOR COOLING SUNDAY
AFTERNOON AND EVENING. /PELATTI
SUNDAY NIGHT THROUGH MONDAY...THERE IS REASONABLE MODEL AGREEMENT
FOR THE MONDAY PERIOD SUGGESTING A WEAKENING OF THE UPPER LEVEL
RIDGE OVER THE REGION...BUT THE STORM TRACK WILL STILL REMAIN WELL
TO THE NORTH OF THE FORECAST AREA. THUS NO SIGNIFICANT
PRECIPITATION CHANCES YET...BUT A SLIGHT COOLING TREND LOOKS
PLAUSIBLE ON MONDAY. MONDAY NIGHT AND TUESDAY MODEL AGREEMENT
CONTINUES TO ADVERTISE THE PASSAGE OF A SIGNIFICANT UPPER LEVEL
WAVE THROUGH THE REGION. THERE ARE MINOR TIMING DIFFERENCES
BETWEEN THE GFS/ECMWF AND CANADIAN MODEL REGARDING THE ASSOCIATED
COLD FRONT PASSAGE...BUT THERE IS ENOUGH AGREEMENT TO ALLOW
INCREASING CONFIDENCE THAT ON OR ABOUT TUESDAY WILL BE THE NEXT
SIGNIFICANT CHANCE OF PRECIPITATION ALONG WITH A NOTICEABLE COOLING
TREND.
BY WEDNESDAY MODEL AGREEMENT REGARDING THE NATURE OF THE TROUGH
DEGENERATES...WITH THE GFS SWEEPING THE TROUGH THROUGH THE REGION
AND COMMENCING AN NEW RIDGE CYCLE...WHILE THE ECMWF AND CANADIAN
MODELS SLOW AND DIG THE TROUGH INTO A DEEP MEAN TROUGH OVER THE
WESTERN USA. CONFIDENCE IS THUS LOWER FOR THESE FAR PERIODS...BUT
WILL HEDGE FORECAST TOWARD THE ECMWF AND CANADIAN CONSENSUS FEATURING
A MORE SHOWERY AND UNSETTLED COOLER REGIME CHARACTERISTIC OF A
MEAN TROUGH OVER THE REGION. /FUGAZZI
AVIATION
A STRONG HIGH PRESSURE RIDGE WILL CONTINUE TO BUILD OVER THE
INLAND NORTHWEST THROUGH SATURDAY. VFR CONDITIONS WITH MAINLY CLEAR
SKIES AND LIGHT WINDS ARE EXPECTED AT ALL TAF SITES THROUGH 00Z
SATURDAY. /EK
PRELIMINARY POINT TEMPS/POPS
SPOKANE 51 86 57 89 58 84 / 0 0 0 0 0 0
COEUR D'ALENE 48 85 50 87 52 84 / 0 0 0 0 0 0
PULLMAN 49 85 51 87 53 83 / 0 0 0 0 0 0
LEWISTON 54 91 58 94 60 91 / 0 0 0 0 0 0
COLVILLE 47 88 49 91 51 89 / 0 0 0 0 0 0
SANDPOINT 44 82 49 83 50 81 / 0 0 0 0 0 0
KELLOGG 46 81 45 83 49 81 / 0 0 0 0 0 0
MOSES LAKE 54 92 58 95 59 91 / 0 0 0 0 0 0
WENATCHEE 59 92 62 95 64 90 / 0 0 0 0 0 0
OMAK 53 92 52 95 55 90 / 0 0 0 0 0 0
OTX WATCHES/WARNINGS/ADVISORIES
ID...FLOOD WATCH THROUGH SATURDAY MORNING FOR CENTRAL PANHANDLE
MOUNTAINS...COEUR D'ALENE AREA...IDAHO PALOUSE...LEWIS AND
SOUTHERN NEZ PERCE COUNTIES...LEWISTON AREA...NORTHERN
PANHANDLE.
WA...FLOOD WATCH THROUGH SATURDAY MORNING FOR EAST SLOPES NORTHERN
CASCADES...NORTHEAST MOUNTAINS...OKANOGAN HIGHLANDS...
OKANOGAN VALLEY...SPOKANE AREA...WASHINGTON PALOUSE...
WATERVILLE PLATEAU...WENATCHEE AREA.
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