Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 221237 CCB

Area Forecast Discussion...Corrected
National Weather Service Pendleton OR
437 AM PST Wed Feb 22 2017

Removed mention of expired Winter Weather Advisory from the bottom
of this discussion

.SHORT TERM...Today through Friday...An upper level trough will
remain over the Pacific Northwest through Thursday. This will keep
unsettled and showery weather over the region until then. Currently
the trough axis is offshore and a moist southwesterly flow is
feeding snow showers that continue over the Northern Blue Mountains.
The snow showers are diminishing but may need to extend the current
Winter Weather Advisory for a few more hours. Currently an upper low
is moving south along the British Columbia coast and will reach the
Washington coast by this afternoon. This will help develop a west to
southwest flow and a chance of snow showers over Central Oregon and
the mountains, possibly mixed with rain this afternoon.
Precipitation amounts will be light, so am expecting less than an
inch of snow even in the mountains. Temperatures will be cooler than
yesterday, in the 30s and lower 40s. Tonight the upper low will move
ashore and to the Washington Cascade Crest. This will turn the upper
flow from southwest to northwest and cut back even further on the
showers. Upslope flow will keep a slight chance of light snow
showers over Central Oregon and the mountains. Snow amounts will
generally be half inch or less. Lows tonight will be colder as well
and in the mid teens to mid 20s. Thursday and Thursday night the
trough axis will be over our area and the northwest flow will
continue. This will keep a slight chance to a chance of snow showers
over Central Oregon and the mountains, mixed with some rain in the
afternoon, while the rest of the area continues to be dry. Snow
amounts will continue to be around a half inch or less each 12 hour
period. Temperatures Thursday will be in the upper 20s and 30s while
the lows Thursday night will be mainly in the teens and lower 20s.
Friday another upper low will move south of the Canadian Rockies to
offshore near Astoria in the afternoon. This will turn the flow
westerly and allow Central Oregon to mostly dry out while the
mountains will continue to have a slight chance of light snow
showers. Temperatures Friday will remain in the upper 20s and 30s.

.LONG TERM...Friday night through Wednesday...A cool weather pattern
will remain in place through the extended. A shortwave in western
Canada will move off the Pacific Northwest coast late Friday and
Saturday as a closed low before eventually dropping south into
California on Sunday. This will bring some cooler air into the
region along with a chance of snow Friday night and Saturday. A
second shortwave will come out of western Canada late Sunday and
Monday which could combine with some moisture coming up from
California over eastern Oregon for more chance of snow. The upper
level trough begins to shift east Tuesday and Wednesday placing the
Pacific Northwest under a northwest flow. Depending on the amount of
moisture in this flow we could see some continual snow mainly in the
Washington Cascades and the Blue Mountains.


.AVIATION...12Z TAFs...Mainly VFR conditions are expected over the
next 24 hours though MVFR cigs/vsby possible near showers. Winds
will be 5-15 kts.


.HYDROLOGY...While showers have ended over parts of South Central
and Southeast Washington, temperatures remain above freezing and
will warm to the low 40s this afternoon. This will continue the
current snow melt. Areal flood advisories remain in effect for parts
of this area through at least this afternoon. The snow melt will
continue to cause runoff with ponding possible on area roadways and
low lying areas. Localized washouts and undermining of roadways is
likely. Be sure to follow all road closures and never drive around
flood barriers. Perry


PDT  41  24  37  25 /  10  10  30  10
ALW  44  26  38  25 /  20  10  20  10
PSC  43  25  40  24 /  10  10  10  10
YKM  41  21  39  20 /  10  10  20  10
HRI  42  25  39  23 /  10  10  10  10
ELN  36  17  35  16 /  10  10  20  10
RDM  38  20  36  17 /  30  20  30  20
LGD  40  24  35  18 /  20  20  30  20
GCD  39  23  35  21 /  30  20  40  20
DLS  42  28  40  26 /  20  10  20  20





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