070 
fxus66 kpdt 192136 
afdpdt 


Area forecast discussion 
National Weather Service Pendleton or 
235 PM PDT Friday Mar 19 2010 


Short term...tonight through Monday...a ridge of high pressure will 
remain over the area through tomorrow. The ridge axis will move from 
offshore this afternoon to near the Washington-Oregon-Idaho border 
by Saturday afternoon. This will give the area clear skies and fair 
weather until then. Tonight should be another cool evening as clear 
skies and light winds allow for radiative cooling but with a warmer 
air mass...temperatures will be several degrees warmer overall from 
last night. Tomorrow will also see a good warmup over today as the 
ridge axis moves overhead. Temperatures will be in the 60s in most 
locations with middle 50s to lower 60s in the mountains. In the 
afternoon a trough will approach the coast and skies will begin 
clouding up. Pressure gradients will tighten up and afternoon and 
evening winds will pick up to 10 to 20 miles per hour with 15 to 25 miles per hour in the 
Grande Ronde Valley. A few rain showers will move into the Cascades 
after midnight Saturday night and rain showers will gradually cross 
the area except for Wallowa County during the day on Sunday. Behind 
the front...a trough will follow and this will keep rain showers 
continuing over the entire region through Sunday night. Colder air 
will come in with the trough and snow levels will drop from around 
7000 feet to 5000 feet Sunday night. Precipitation amounts are not 
that substantial so snow amounts will be on the order of 1 to 3 
inches. Monday will see mainly mountain rain showers as the lower 
elevations dry out. Temperatures will drop several degrees Sunday 
and again on Monday putting US back in the 50s and lower 60s. Perry 


Long term...Monday night through Friday...the 12z runs of the GFS 
and the European model (ecmwf) are in fairly good agreement through the long term 
period. Rain showers and snow showers will continue Monday night as 
the low moves into the Great Basin and sends wrap-around moisture 
into the area. Precipitation is expected to taper off on 
Tuesday...but a few showers could be possible over the eastern 
mountains due to upslope flow. A ridge of high pressure will then 
strengthen over the area on Tuesday night for drier conditions that 
should last through Wednesday afternoon. Another fast moving trough 
will push through the region Wednesday night and Thursday...bringing 
a chance of rain and mountain snow. There may be a brief break in 
the activity on Thursday night...but a second stronger trough is 
forecast to move inland on Friday. 82 




&& 


Aviation...00z tafs...only a few high thin clouds will move across 
the area today and tonight. Otherwise...expect VFR condition with 
light winds under 15 kts. 82 




&& 


Preliminary point temps/pops... 
PDT 30 64 39 60 / 0 0 0 30 
alw 34 64 42 62 / 0 0 0 30 
psc 29 64 39 61 / 0 0 0 20 
ykm 30 63 37 60 / 0 0 10 30 
hri 28 65 38 62 / 0 0 0 20 
eln 29 62 38 59 / 0 0 10 40 
rdm 24 68 34 58 / 0 0 10 20 
lgd 29 58 37 60 / 0 0 0 20 
gcd 29 62 36 61 / 0 0 0 20 
dls 31 64 41 58 / 0 0 20 40 


&& 


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


Threat index 
Saturday : green 
Sunday : green 
Monday : green 


Green: none or limited need for watches, warnings, or advisories. 
Yellow: a few watches, warnings, or advisories possible or in effect. 
Red: numerous watches, warnings, or advisories possible or in effect. 


For additional weather information, check our web site at... 
www.Weather.Gov/Pendleton 


$$ 


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