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Area Forecast Discussion (AFD)

Issued by Pendleton, OR (PDT)

FXUS66 KPDT 211518

Area Forecast Discussion
National Weather Service Pendleton OR
818 AM PDT Wed Aug 21 2019

.SHORT TERM...Today and tonight...A cold front is coming onshore 
this morning as the leading edge of an upper level trough that will 
pass over the forecast area this afternoon and overnight. Models 
are indicating that the front will be weakening as it moves across 
the forecast area but none the less it will hold together and sweep 
a band of precipitation across the forecast area. It will move over 
the Cascades this afternoon and then the rest of the forecast area 
this evening. The front will also be accompanied by some breezy 
westerly winds for a couple of hours. There is some weak instability 
over far eastern Oregon where a slight chance of thunderstorms 
exists this evening ahead of the front. Western portion of the 
forecast area will begin to see cooler air arrive this afternoon so 
high temperatures will be 10 to 15 degrees cooler today while 
eastern areas will along be around 5 degrees cooler.  


.PREV DISCUSSION... /issued 228 AM PDT Wed Aug 21 2019/ 

SHORT TERM...Today through Thursday night...Upper level trough will 
move across the area today and tonight exiting the region by 
Thursday morning. This will drive a rather strong cold front across 
the region this afternoon and evening. The main effects from the 
front will be a period of gusty winds along the front and for 2-3 
hour afterwords. Winds could reach 20-30 mph with some gusts to 35 
to 40 mph. The short duration of the wind threat precludes issuing a 
wind advisory at this time. The winds will certainly push around any 
existing fires but as the winds pick up the humidities will increase 
rapidly behind the front. So for now will not be issuing any fire 
weather highlights. There is a slim chance of thunderstorms in the 
far east mainly between 00Z-03Z with best potential albeit limited 
in Wallowa County. Otherwise a few showers can be expected areawide 
beginning in the west this afternoon and spreading eastward this 
evening. QPF amounts will be .10-.25 inches near the Cascades and 
01-.10 inches elsewhere. From Thursday through Friday night the 
weather will become quiet again with just a few clouds from time to 
time. It will be cool Thursday with slightly below normal 
temperatures...but rebounding to near normal by Friday afternoon. It 
will be chilly Friday morning with lows 48-55 in the lower 
elevations and 38-45 in the mountains and high plateaus. 78 

LONG TERM...Saturday through Tuesday. The region will remain in a 
dry weather pattern this weekend and next week as a ridge of high 
pressure builds into the pacnw. Pressure gradients may become tight 
and breezy west winds are possible this weekend especially in the 
gorge. The models may be under doing the warm temperatures that 
could climb into the 90s. 

AVIATION...12Z TAFS...Despite a weather system that is forecast to 
move through the region today that could produce a shower...mainly 
vfr conditions can be expected. However brief wind gusts between 25 
kts to 30 kts are possible from 20z to 02z.


PDT  87  55  79  50 /   0  60   0   0 
ALW  90  59  81  57 /   0  60   0   0 
PSC  91  59  84  54 /   0  60   0   0 
YKM  85  51  81  53 /  60  30   0   0 
HRI  87  56  83  51 /   0  60   0   0 
ELN  81  53  78  52 /  60  30   0   0 
RDM  82  44  80  42 /  50  50   0   0 
LGD  89  52  77  46 /   0  70   0   0 
GCD  89  52  78  48 /   0  60   0   0 
DLS  78  56  78  55 /  70  30   0   0