168 
fxus66 kpdt 221035 
afdpdt 


Area forecast discussion 
National Weather Service Pendleton or 
235 am PST Sat Nov 22 2008 


Short term...today through Sunday night...a fast moving but 
moisture starved cold front is passing through the region this 
morning. Radar and satellite shows that there is not a lot of 
precipitation occurring with the front over southern Washington and 
even less over Oregon at this time. So I have lowered chance of 
precipitation to just isolated and scattered showers mainly over the 
far eastern mountains this morning and then decreasing through the 
day. Overall this front is not as impressive as models advertised. 
Front will exit eastern Oregon later today followed by ridge of high 
pressure building back over the region. This will allow inversions 
to rebuild tonight and Sunday night resulting in the development of 
patchy fog. Columbia Basin temperatures will also turn cooler on 
Sunday due to the inversion while higher elevations will see a 
slight warming trend as the ridge builds over the area. 


Long term...Monday through Friday night...while both models seem to 
be in decent agreement for the near and Middle Range of the 
forecast...the current model of choice is the European model (ecmwf). A blocking 
pattern looks to occur and hold off the progression of the next 
system...as a ridge of high pressure sets up over The Rockies 
Monday. Morning fog will be a concern as always along the lower 
Columbia Basin and the foothills of the Blue Mountains. We will 
start to see a slight chance of rain showers off the east slopes of 
the Cascades Tuesday and perhaps some sprinkles along the blue and 
Wallowa Mountains. Models are still depicting an upper level low 
pressure system off the Southern California coast with a weak upper 
level trough to the north of our area Tuesday night. While it is not 
out of the question for precipitation in the lower elevations...have 
decided to keep probability of precipitation out of the forecast Wednesday. Due to model 
uncertainty in the extended no other changes have been made. 
Thursday and Friday...models really begin to diverge from this point 
on. Both models indicate another upper level disturbance to push 
across the area as early as Thursday or as late as Friday...and both 
models seem to agree that this disturbance is to interact with 
tuesdays low pressure system to our south...however the progression 
of the two models is quite different. While the GFS has the two 
systems rotating around the or/ID/NV/CA area and suggesting 
widespread precipitation across the County Warning Area...European model (ecmwf) has a ridge building 
in off the southern californian coast Friday with the upper level 
trough forced to slide down over ID/Mt/co. As it merges with the low 
they quickly push off to the east and form a deep trough over the 
Central Plains...and a strong upper level ridge begins to set in 
place over the Pacific northwest. This is the first we are seeing of 
the upper level ridge from previous runs...so while European model (ecmwf) in the 
model of choice for the near and Middle Range of the forecast...there 
is still some speculation as to the solution in the extended. Weber 




&& 


Aviation...06z tafs...generally VFR conditions will continue at all 
taf sites for the next 24 hours. There may be brief periods of MVFR 
early this morning at kalw and kpdt as rain showers occur due to a 
passing cold front. Patchy fog development is possible tonight. 




&& 


Preliminary point temps/pops... 
PDT 53 30 50 30 / 20 0 0 0 
alw 54 32 49 32 / 20 0 0 0 
psc 55 30 48 27 / 10 0 0 0 
ykm 52 29 46 29 / 0 0 0 0 
hri 55 29 49 28 / 10 0 0 0 
eln 47 28 42 29 / 10 0 0 0 
rdm 49 25 51 28 / 10 0 0 0 
lgd 44 26 44 29 / 20 10 0 0 
gcd 45 27 49 29 / 20 10 0 0 
dls 54 32 48 32 / 10 0 0 0 


&& 


PDT watches/warnings/advisories... 
or...none. 
Washington...none. 
&& 


$$ 


Ti:ggg 
for additional weather information, check our web site at... 
www.Weather.Gov/Pendleton 
91/89/89