Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 282205
AFDPDT

DDHHMM 282136
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
300 PM PDT Tue Mar 28 2017

.SHORT TERM...Tonight through Thursday night...A warm front with
attendant moisture and lift will move into the forecast area tonight.
Rain expected beginning this evening along the east slopes of the
Washington Cascades and rain arriving at the crests of the Oregon
Cascades late in the evening. Rain will spread east across the
region overnight with valley rain likely in the Lower Columbia Basin
and the northern Foothills of the Blue Mountains as well as rain and
snow likely in the Blue Mountains where snow levels will be 5000-
6000 feet overnight. Snow Levels rise Wednesday morning to 65000-
7500 feet along the east slopes of the Washington Cascades and rise
to 7500-8500 feet in the central and eastern mountains in Oregon.
The rain and high snow levels will produce runoff due to the rain
and snowmelt, thus yielding rising creeks streams and rivers through
the day on Wednesday and water levels continuing to rise Wednesday
night into Thursday morning. Wednesday night a cold front enters the
interior Pacific Northwest and moves slowly east through overnight.
Thursday morning the cold front exits into Idaho while the mid/upper
trough that pushed the cold front through the region closes off and
moves southeast across central and northeast Oregon during the the
day, which results in wrap around moisture giving a chance of snow
showers in the Blue Mountains and the Wallowa Mountains through
Thursday afternoon into Thursday evening. Snow levels lower to
around 3500 feet by Thursday morning in the northeast Oregon
mountains. Snow showers in the eastern mountains taper off by around
midnight with overnight prior to day break on Friday morning dry
areawide.  Polan

.LONG TERM...Friday through Tuesday...The region looks to be under a
weak upper ridge, and between systems, Friday and Friday night. Thus
expect mainly dry conditions during these two periods. A moist and
unsettled west to northwest flow looks to develop Saturday. This
pattern then looks to persist into Monday. For now, precip chances
on Saturday look to be limited to the mountains. Precip chances then
are expected to increase Saturday night through Monday with the best
chances over the higher terrain. Confidence is still low enough
during this period to only indicate precip chances of 20 to 40
percent. Weak ridging may move over the area Tuesday for a decrease
in precip chances. Temps look to be near or slightly below seasonal
through this period. 90

&&

.AVIATION...Previous Discussion...18Z TAFs...Warm air advection
aloft will keep conditions mostly cloudy to cloudy today. Conditions
will be VFR with cigs running between 5000 and 11000 ft AGL. Spotty
light precip will work into the area this evening, with steadier
precip expected overnight into Wednesday morning. At this time,
expect cigs/vis to remain VFR tonight into Wednesday with cigs
running between 3500 and 7000 ft AGL. MVFR cigs may develop late in
the period at KPDT and KALW, but confidence is low and will keep VFR
for now. Southwest to west winds of 10 to 15 kts will be possible at
all sites today, and at KPSC, KRDM and KBDN late in this period. 90

&&

99/90/90



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