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Area Forecast Discussion (AFD)

Issued by Pendleton, OR (PDT)

FXUS66 KPDT 260930

Area Forecast Discussion
National Weather Service Pendleton OR
230 AM PDT Fri Apr 26 2019

.SHORT TERM...Today through Sunday. Two cold fronts will be 
traveling across the forecast area today and Saturday.  The cold 
front on Saturday will definitely be the stronger system with very 
windy conditions and areas of blowing dust followed by significantly 
cooler air Saturday night and Sunday.  The cold front arriving today 
is offshore and will quickly move inland early this morning then 
east of the Cascades by mid morning and during the afternoon.  The 
biggest impact with today's cold front will be the increasing winds, 
and the winds in the Kittitas Valley and the Eastern Columbia River 
Gorge will be flirting with wind advisory criteria this afternoon--
i.e. sustained winds around 30 mph with gusts up to 45 mph.  Other 
areas in and around the Columbia Basin will have winds 15-25G35 mph. 
Many fields have been recently plowed ready for seeding with the 
possibility of patchy blowing dust.  This is a dry cold front with 
only isolated mountain showers.  Temperatures today will be slightly 
cooler than yesterday.

Saturday's cold front will be accompanied by an upper level 
shortwave trough aided by a 125kt northwest jet at 250mb.  Winds on 
Saturday will be stronger than today, and confidence is high that 
the Kittitas Valley and the Eastern Columbia River Gorge will have 
wind advisory criteria.  Since this is out to the 3rd-4th period in 
the forecast, will hold off on wind highlights for these two areas 
and allow the upcoming shift to have a better feel of sustained 
winds and gusts.  Wind advisories may also be needed for the Lower 
Columbia Basin, Blue Mountain Foothills, and north central Oregon 
but confidence is not as high.  There will be a better potential for 
blowing dust. Scattered mountain showers are expected along the 
southern WA Cascades and far northern Blues with isolated mountain 
showers elsewhere.  Snow may be observed down to 2500 feet but any 
accumulations will be 0.5 inch or less.  Colder and drier air behind 
the front will bring overnight lows Saturday night in the mid 20s to 
mid 30s for most of the forecast area. Outdoor plants may experience 
frost.  Highs on Sunday will be in the 40s over the mountains and 
50s to lower 60s elsewhere with northerly winds 5-15 mph.   Wister

.LONG TERM...Sunday night through Friday...An upper level trough 
will sharpen over the area Sunday night through Tuesday in nw flow 
aloft. The nw trajectory will not allow much moisture to spread over 
the area with just a slight chance for showers mainly Monday and 
Tuesday afternoon. There could be enough instability for a stray 
thunderstorm but given meager instability several days out have 
chosen not to include thunderstorms in the forecast for now. It will 
be cool early in the week with below normal temperatures and 
especially chilly at night. The mountains and high plateaus will 
likely be below to well below freezing Monday through Wednesday 
morning. Even the lower basins will see low temperatures mainly in 
the 30s. As the trough passes by the area flat nw flow with mostly 
dry and moderating conditions are expected for the end of the week. 
By Friday temperatures may be a bit above normal with highs in the 
lower to mid 70s lower elevations with 60s in the mountains. 78  


.AVIATION...12Z TAFS...VFR conditions will prevail through the 
forecast period. SCT-BKN high level clouds and a few mid level 
clouds are forecast through tonight. The main concern will be the 
winds this afternoon and evening. Westerly winds of 15-25 kt with 
some higher gusts are expected mainly 18Z-03Z. Strongest winds will 
be at KDLS and KPDT. 78


PDT  66  42  57  35 /  10   0   0  10 
ALW  70  44  59  35 /  10   0  20  10 
PSC  74  47  63  38 /  10   0   0   0 
YKM  69  42  58  34 /   0   0   0   0 
HRI  72  45  61  36 /  10   0   0  10 
ELN  62  39  51  32 /   0  10  10   0 
RDM  66  36  60  28 /   0   0   0   0 
LGD  61  38  56  31 /  10   0  10  10 
GCD  63  38  60  31 /   0   0   0  10 
DLS  68  44  59  35 /   0   0  10   0