Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 282332
AFDPDT

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

Corrected

.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. Rain shadowing expected in central Oregon
overnight so went with just a slight chance of rain through tonight
for Bend and Redmond. Mesoscale models are showing rain shadowing
immediately east of the Cascades at lower elevations during the day
on Wednesday so significant measurable rain is not expected at the
usual rain shadowed locations from daybreak through Wednesday
afternoon. Snow Levels rise through the day on Wednesday to 6500-
7500 feet in the afternoon along the east slopes of the Washington
Cascades and rise to 7500-8500 feet in the afternoon 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. Crests at main stem river forecast
points are expected late Wednesday into Thursday morning.

Wednesday night a cold front enters the interior Pacific Northwest
and moves slowly east through overnight for the best chance of
significant rainfall. 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 on Thursday, 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 and end Thursday evening with overnight
prior to daybreak 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...00Z TAFs...A moist west-northwest flow aloft with
associated warm air advection will keep conditions mostly cloudy to
cloudy. Also will see increasing chances of precipitation this
evening and overnight. Periodic shadowing will lead to spottier
precip at KRDM and KBDN, especially tonight and Wednesday morning.
Elsewhere, expect to see the gradual development of steady rain.
This steady rain will be most persistent at KPDT and KALW on
Wednesday. KYKM should see precip largely end by Wednesday
afternoon. Cigs will mainly run between 3500 and 9000 ft AGL, though
MVFR cigs should develop at KPDT and KALW due to the persistent rain
and upslope affects. Breezy winds at KPSC should decrease by 29/03
UTC. Otherwise expect winds to be 15 kts or less, though the winds
should become gusty at KBDN Wednesday afternoon. 90

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  43  60  42  54 /  60  80  80  40
ALW  47  61  45  55 /  60  90  80  50
PSC  46  62  45  60 /  70  30  50  20
YKM  44  63  41  63 /  60  20  30  20
HRI  43  60  43  58 /  60  60  60  30
ELN  39  55  39  54 /  70  30  30  20
RDM  42  60  36  51 /  20  20  70  30
LGD  41  57  40  53 /  50  90 100  60
GCD  40  62  41  50 /  30  80  90  80
DLS  46  58  44  59 /  60  20  60  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&

$$

99/90/90


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