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fxus66 kotx 041738 
afdotx 


Area forecast discussion 
National Weather Service Spokane Washington 
938 am PST Thursday Dec 4 2008 


Synopsis...high pressure will keep the inland northwest dry and cool 
through Friday. Moisture from the Pacific will begin to spread 
across the northern mountains on Saturday. A cold front will move 
through the region on Sunday for the best chance of precipitation... 
mainly in the mountains. A brief break will occur on Monday before 
another wet Pacific storm moves into the area on Tuesday and 
Wednesday. 




&& 
Updated aviation section.. 


Discussion... 
today and tonight...dry air continues to filter down from the 
north as dewpoints have fallen into the teens as far south as 
Moses Lake. Middle/high clouds are exiting to the south so clear 
skies are allowing temperatures to drop into the teens in the 
sheltered areas with 20s in the breezy locations. Temperatures 
today will struggle to warm above freezing north of I-90. Abundant 
sunshine should help though. 


Abundant clouds west of the off-shore high pressure ridge are 
dissipating rapidly as they come over the ridge. Still should see 
some wispy cirrus moving into the area late this afternoon and 
tonight...but probably not enough to make much of a difference on 
temperatures. Models all agree that pressure gradients will relax 
tonight so many locations will go calm allowing temperatures to 
drop into the teens. Rj 


Friday through Sunday...models in okay agreement of the upper 
level ridge flattening Friday and Saturday before an upper level 
trough and associated cold front move through on Sunday. Models 
have discrepancies in where to place precipitation starting as early as 
Friday night and Saturday. The NAM produces lots of quantitative precipitation forecast across the 
Idaho Panhandle Saturday...while the GFS is a lot drier. Trended forecast 
towards the GFS which is similar to the European model (ecmwf) and Canadian and 
kept the precipitation mainly in the north. Took out mention of rain in 
the basin as westerly flow will shadow this location. Main 
forecast concern in the entire middle and extended period is the warm 
850 temperatures moving into the area Friday night and Saturday. 
The potential exists for freezing rain across the northern valley 
locations. Both the NAM and GFS do keep the extreme northern Idaho 
Panhandle below 0c at 850 mb through Saturday afternoon. The 
challenge is how quickly will the warmer temperatures mix down to 
the surface and scour out the sub-freezing temperatures. Would think 
personally that it will take a bit longer than advertised by the 
forecast models. Kept mention of slight chance of freezing rain 
after midnight Friday night and all day Saturday north of a line 
from Omak to Deer Park to Sandpoint. 


Sunday an upper level trough moves across. The ec and GFS have a 
bit different track with the ec further south and both models have 
backed off a bit on precipitation amounts. However given the good upper 
level support and good upglide from the 285k isentropic 
analysis...think locations east of a line from Republic to 
Davenport to Pullman have a decent shot of measuring precipitation. 


Sunday night through Thursday...snow levels drop Sunday night 
after the front passes. The upper level ridge builds right back up 
along the West Coast by Monday. Forecast challenge here is 
moisture streaming over the ridge and into the Pacific northwest. Kept the 
best chance of precipitation occurring over the mountains through the 
remainder of the forecast period. /Nisbet 


&& 


Aviation... 
dry air from Canada will continue to keep skies clear today. Areas 
of stratus will linger between kpuw and klws through 20z. Some high 
clouds will filter into the area from the north this afternoon and 
overnight but conditions will remain VFR at all sites. Rfox 


&& 


Preliminary point temps/pops... 
Spokane 32 19 33 25 37 30 / 0 0 0 10 30 20 
Coeur D'Alene 34 21 37 26 39 31 / 0 0 0 10 40 20 
Pullman 39 25 42 29 43 35 / 0 0 0 0 20 20 
Lewiston 41 27 42 30 45 36 / 0 0 0 0 10 10 
Colville 34 18 33 22 33 28 / 0 0 0 40 50 20 
Sandpoint 34 19 33 23 33 30 / 0 0 0 40 50 30 
Kellogg 35 22 36 27 38 32 / 0 0 10 10 40 30 
Moses Lake 37 21 36 25 39 29 / 0 0 0 0 10 10 
Wenatchee 39 23 37 28 40 36 / 0 0 0 0 10 10 
Omak 36 21 35 25 36 29 / 0 0 0 20 20 10 


&& 


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


$$ 

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