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fxus66 kotx 221147 
afdotx 


Area forecast discussion 
National Weather Service Spokane Washington 
447 am PDT Monday Mar 22 2010 


Synopsis... 
a fast moving disturbance will move across Washington and into 
Oregon and Idaho bringing rain and mountain snows to the Cascades. 
High pressure will build over the northwest Tuesday into Wednesday 
providing mild temperatures. Precipitation chances will increase 
later Wednesday night into Thursday. 


&& 


Discussion... 
today and tonight...a fast moving shortwave seen on water vapor 
animation was diving southward western Washington and southwestern 
British Columbia. Heavier showers associated with this feature were noted near 
Friday Harbor in northwest Washington. With a 70 knot jet maximum on the 
backside of the shortwave...it will dig a little farther south 
across Oregon by later today. Showers associated with this feature 
will occur over the Cascades. The shortwave elongates across Oregon 
into northern Idaho. Due to this feature expect continued light rain 
and mountain snow over this area today and perhaps into this 
evening. By tonight the region will be under the influence of an 
upper ridge. Lingering light precipitation will be possible 
generally before midnight in the higher elevations of the Cascades 
and near the Clearwater Mountains in north Idaho. /Ac 


Tuesday and Tuesday night...high pressure will begin to build into 
the region during this period. Upper level flow will turn out of 
the north northwest...resulting in drier conditions across the 
region. Drier flow combined with the large scale subsidence under 
the ridge should result in mostly clear skies. 850 mb temperatures will 
be increasing with a 24hr change of about 2 degree celsius...this 
should translate to a fairly mild period with highs and lows close 
to or slightly above average. /Svh 


Wednesday through Sunday...upper level ridge axis gets shifted to 
the east Wednesday as an upper level low nears the West Coast. 
Models have backed off on the timing and conditions will remain 
dry through Wednesday night. The exception to this will be the 
Cascade crest which will see the effects of the front first...by 
early Thursday morning. The front will move across the inland 
northwest during the day on Thursday for a shot of widespread 
rain. Southwest winds will increase in the afternoon and carry on 
through the early evening hours. Gusts up to 30 miles per hour is possible 
across the upper Columbia Basin and Palouse. The upper level trough 
moves in Friday. 500 mb temperatures will be around -30 c and therefore 
kept mention of instability showers in the forecast. Friday night an 
upper level ridge begins to push onshore and showers will decrease. 
Saturday looks to be a dry day with the ridge in place. Sunday the 
ridge starts to get pushed to the east as a the next series of waves 
begins to move towards the West Coast and ride up the ridge. Models 
are slowing the timing...and lowered chance of precipitation a little bit 
for Sunday...but it may need to be lowered even more. Sunday night 
and Monday have mention of chance of precipitation everywhere. Temperatures 
will remain at or slightly above average for this time of the year. 
/Nisbet 


&& 


Aviation... 
in the near term...MVFR conditions will plague kpuw and possibly 
klws through middle morning. Otherwise widely scattered showers can be 
expected generally after 18z. Confidence is low that any particular 
site will experience measurable precipitation...however kcoe has the best 
shot. Increasing winds this afternoon in the wake of the upper level 
shortwave passage may be the biggest factor for kmwh and keat after 
20z. Conditions will improve to VFR after 03z and winds will subside 
through the night for kmwh and keat. /Ac 


&& 


Preliminary point temps/pops... 
Spokane 49 29 53 32 57 38 / 30 10 0 0 0 0 
Coeur D'Alene 48 29 53 30 57 35 / 30 10 0 0 0 0 
Pullman 48 33 53 32 60 39 / 30 10 0 0 0 0 
Lewiston 51 36 57 36 64 44 / 40 10 0 0 0 0 
Colville 52 32 57 30 59 36 / 30 10 0 0 0 0 
Sandpoint 46 28 50 32 54 33 / 50 10 0 0 0 0 
Kellogg 44 29 51 31 56 37 / 60 20 0 0 0 0 
Moses Lake 56 32 58 33 62 40 / 0 0 0 0 0 0 
Wenatchee 55 36 57 35 61 40 / 0 0 0 0 0 10 
Omak 54 34 57 32 60 37 / 10 0 0 0 0 0 


&& 


Otx watches/warnings/advisories... 
Idaho...none. 
Washington...none. 
&& 


$$