190 
FXUS66 KPDT 062343 AAA
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
440 PM PDT Wed Oct 6 2021

updated the aviation discussion

.SHORT TERM...Wednesday through Friday...A cold front moving east 
out of our forecast area will leave clear skies and cooler 
temperatures in its wake. Visible satellite imagery showing the 
front, along with some light embedded showers over the Wallowas, 
continuing its eastward progression through the afternoon, before 
the upper-level trough axis associated with this front centers 
itself over the CWA this evening. The light winds and clear skies 
that result could lead to some cold overnight lows, with some areas 
below the mountains approaching freezing.

The upper-level trough will split a bit as it pushes more onshore, 
leading to a more SW-oriented flow aloft, which could inject some 
light cloud cover over the area, mainly from central OR extending up 
through the eastern mountains. While this may partially insulate the 
surface and prevent temps from sinking too low, will still upgrade 
our current freeze watches to warnings for central OR and the Grande 
Ronde Valley. Current thinking is that cloud cover will bring temps 
right at or just below freezing, rather than well below as 
previously forecasted.

Thursday onward, the synoptic pattern becomes light SW to almost dry 
zonal as the splitting trough broadens out, making for quiet weather 
for the rest of the work week. Some of the moisture advection into 
the south central and eastern mountains of OR may make for weak 
upslope showers Friday as this broadened trough axis moves over the 
area by the end of the week, but not expecting much in terms of 
QPFs. High temps will linger around the 50s and 60s, while mostly 
clear skies and light winds make for chilly overnight lows down into 
the 30s and even 20s for our more elevated valleys. 74

.LONG TERM...Saturday through Wednesday...The long term period will 
see a trough moving through the eastern part of the forecast area 
Saturday and off to the east Saturday night replaced with a zonal 
westerly flow. Sunday night a stronger low and trough will move into 
the area with gusty winds, much colder temperatures and a chance for 
some early snow in the mountains. Troughy conditions and cold 
temperatures will continue through the middle of next week.

Saturday looks to be dry though breezy westerly winds around 15 mph 
is expected for the Columbia Gorge, Kittitas Valley, and the eastern 
portions of the Columbia basin and Blue Mountain Foothills. 
Temperatures will be up a couple of degrees to the lower to mid 60s 
over most of the area. Lows saturday night will be in the 40s with 
30s in central Oregon and the mountains. The approaching low and 
trough will bring a chance of rain to the Cascades in the overnight 
hours. The entire area will have a chance of rain Sunday and Sunday 
evening though with snow levels starting around 6500 feet dropping 
to 4500 feet by early Monday morning morning when the precipitation 
tapers off. Monday morning lows will be in the 30s with 20s in the 
mountains. The trough will be centered to the east of us which will 
limit precipitation to the higher mountains Monday through Tuesday. 
Temperatures will be much colder with highs in the 50s with 40s in 
the mountains. Lows will the coldest so far this fall with portions 
of the Columbia Basin possibly seeing their first subfreezing 
temperatures for a few hours Tuesday morning. Winds will be breezy 
in the Columbia Basin and Central Oregon Monday and Tuesday 
afternoons. Models begin to have differences by Tuesday night and 
Wednesday with the strength and timing of the next system but have 
kept a slight chance of rain and mountain snow for Wednesday. 
Tuesday night will be a couple of degrees warmer but still cold due 
to the increasing cloud cover. Wednesday will be mainly in the mid 
40s to mid 50s. Perry/83 


&&

.AVIATION...vfr conditions will persist at all taf sites for the 
next 24 hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  35  60  35  59 /   0   0   0   0 
ALW  39  62  38  62 /   0   0   0   0 
PSC  42  64  39  64 /   0   0   0   0 
YKM  33  62  33  63 /   0   0   0   0 
HRI  38  63  38  64 /   0   0   0   0 
ELN  34  60  34  61 /   0   0   0   0 
RDM  30  59  31  59 /   0   0   0   0 
LGD  32  60  34  61 /   0   0   0  10 
GCD  34  64  37  63 /   0   0   0  10 
DLS  42  65  43  66 /   0   0   0   0 

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Freeze Warning from 2 AM to 9 AM PDT Thursday for ORZ049-511.

WA...None.
&&

$$

SHORT TERM...74
LONG TERM....83
AVIATION...97