605 
FXUS66 KPDT 151045
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
245 AM PST Sun Dec 15 2019

.SHORT TERM...Today through Tuesday night...There will be a 
continued northwest flow over the region today as an upper level 
ridge off the coast will begin to move onshore today. There is one 
last small shortwave passing in the northwest flow that will 
generate a few showers over northeast Oregon and southeast 
Washington today with showers ending this evening. The upper level 
ridge will then be over the region Monday and Tuesday providing dry 
weather. The next upper level trough will begin to approach the 
coast late Tuesday increasing cloud cover. There will be some fog 
and stratus across the Lower Columbia Basin today with some freezing 
fog advisories in effect until 10am with some areas of dense fog. 
The developing ridge pattern means there will be more growth and 
spread of the fog and stratus through Tuesday as inversions 
strengthen under the ridge.  


.LONG TERM...Wednesday through Sunday...A weakening low pressure 
system will arrive Wednesday afternoon with increasing rain and snow 
across the region. QPF with this first system likely remains under a 
tenth of an inch. Snow levels as this first system moves through 
will range from 500-1000 feet over parts of the Washington Cascades 
and Wallowa Mountains to near 3000 feet over central Oregon with 
only minor snow accumulations possible. 

Better chances for more widespread, impactful rain and mountain snow 
arrive Thursday afternoon and continue through Saturday morning. 
With a relatively mild and persistent southwest flow, snow levels 
expected to increase between 4500-5500 feet across Oregon and 
southeast Washington. For the Washington Cascades snow levels are 
expected to remain between 2000-3000 feet, where winter weather 
highlights may be needed. Models also hinting at the potential for 
cold air to remain trapped across lower elevations of the 
Kittitas/Yakima Valleys and portions of the lower Columbia Basin in 
Washington. With subfreezing temperatures in these areas overnight 
Thursday night and again Friday night, areas of light freezing rain 
will be possible. 

By Sunday the upper level trough begins to weaken and shift south 
and east of the area. This will allow for a drying trend to end the 
weekend; however, slight chances for precipitation will remain for 
the Cascades and higher elevations of central and northeast Oregon. 
Richards


&&

.AVIATION...Areas of mvfr and ifr conditions can be expected 
especially at taf sites kykm...kalw...kpdt. Also taf sites kpsc will 
experience areas of mvfr and lcl ifr into Sunday morning before some 
improvement is likely around 18z. 


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  36  24  35  24 /  10  10   0   0 
ALW  35  28  35  26 /  20  10   0   0 
PSC  36  26  36  25 /  10   0   0   0 
YKM  36  22  35  22 /   0   0   0   0 
HRI  36  27  36  25 /  10   0   0   0 
ELN  34  23  33  21 /   0   0  10   0 
RDM  39  21  42  23 /   0   0   0   0 
LGD  37  23  36  26 /  20  20   0   0 
GCD  36  19  38  25 /  10  10   0   0 
DLS  40  31  39  29 /   0  10   0   0 

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Freezing Fog Advisory until 10 AM PST this morning for ORZ044-
     507.

WA...Freezing Fog Advisory until 10 AM PST this morning for WAZ026-
     027-029.

&&

$$

91/75/75