033 
fxus66 kpdt 022218 cca 
afdpdt 


Area forecast discussion...corrected 
National Weather Service Pendleton or 
206 PM PST Tuesday Dec 2 2008 


Corrected spelling in extended 


Short term...tonight through Friday...overall pattern to remain 
unchanged through Friday with northwest flow aloft regime to persist. A 
weak impulse will move across the NE corner of the County Warning Area tonight 
bringing a slight chance of rain and snow showers with some help 
from upslope flow. A more pronounced and amplifying shortwave trough 
embedded in the flow will move through the area Wednesday 
night...bringing the best chance for rain and snow to the northeast 
quadrant of the County Warning Area. Still not looking for any substantial snow 
accumulations although snow levels will be as low as 1500-2000 feet. 
The system will move to the southeast of the region on Thursday and fair 
weather will resume areawide through Friday. Much cooler weather is 
anticipated the next few days and overnight lows will be noticeably 
colder especially Thursday and Friday morning. Mountain Valley 
locations will easily drop into the teens. In the immediate short 
term...some fog will likely redevelop in the Yakima Valley later 
this evening and have included patchy fog for that area through 
Wednesday morning...coinciding with the expiration of the air 
stagnation advisory. 78 


Long term...Friday night through Tuesday...extended models in fair 
agreement on bringing a fairly vigorous shortwave trough through the 
Pacific northwest on Sunday. Mostly rain will spread over the 
region Saturday night into Sunday. A shortwave ridge will build in 
its wake Monday providing a short reprieve from the inclimate 
weather. However...a more powerful trough swings through the region 
Tuesday resulting in another round of rain and mountain snow. 81 


&& 


Aviation...00z tafs...most taf locations will remain VFR conditions 
through the period. However...conditions at kpsc and kykm will 
deteriorate through the night due to fog and low clouds. IFR 
conditions are expected at both locations by 10z. Kalw may 
experience some periods of reduced visibilities by sunrise. 81 


&& 


Preliminary point temps/pops... 
PDT 37 46 30 39 / 10 10 10 0 
alw 38 46 29 37 / 20 10 20 0 
psc 33 46 28 38 / 10 0 10 0 
ykm 34 46 27 38 / 10 10 10 0 
hri 35 48 26 39 / 10 10 10 0 
eln 34 44 24 39 / 10 10 10 0 
rdm 25 46 22 40 / 0 0 0 0 
lgd 34 45 26 38 / 20 10 20 10 
gcd 29 45 26 40 / 20 10 10 10 
dls 41 49 33 42 / 10 10 10 0 


&& 


PDT watches/warnings/advisories... 
or...none. 
Washington...air stagnation advisory until 12 PM PST Wednesday for waz027. 


&& 


$$ 


Ti:ggg 
for additional weather information, check our web site at... 
www.Weather.Gov/Pendleton 
78/81/81