High Wind Watch 1, NWS Pendleton, OR

Area Forecast Discussion
National Weather Service Pendleton OR
225 AM PST Mon Dec 17 2018

.SHORT TERM...Today through Tuesday night...Shortwave trough will
move across the region today with a decrease in precipitation by
this afternoon. The next in a series of systems will move quickly
into the area tonight with several concerns. Strong winds aloft will
have the potential to mix down to the surface in central Oregon late
tonight and the first part of Tuesday. Local mountain wave tool is
pegging Deschutes County for potential strong downslope winds. Model
cross sections also show strong isentropic descent coming off the
mountains in central Oregon particularly Tuesday morning. Thus will
be issuing a High Wind Watch for the East Slopes of the Oregon
Cascades and Central Oregon zones. At times in these situations
damaging winds occur in the Bend area. Will also issue Wind
Advisories for the Southern Blue Mountain Foothills and North
Central Oregon beginning late this evening through Monday afternoon.
Heavy precipitation is expected over the Northern Blue Mountains
tonight and Tuesday and the consensus of the models suggests that
snow levels initially will be around 4500 feet before rising sharply
Tuesday morning. Thus there could be several inches of snow above
4500 feet affecting the higher state highways and Ski Bluewood
before a change over to rain. For now will issue a Winter Weather
Advisory above 4500 feet for 5 to 9 inches of snow from 7 PM this
evening until 10 AM Tuesday. If snow levels take a little longer to
rise could see warning amounts. BY 2-3 PM Tuesday the winds should
be on the decrease and precipitation should be all rain. By the time
snow levels lower late Tuesday night QPF will be lighter and winter
highlights should not be needed. There is some patchy dense fog
around this morning in the Columbia Basin and adjacent valleys and
have included in the forecast through 18Z. 78

.Long Term...Wednesday through Friday...A progressive weather
pattern will make for an active stretch of days from mid week into
the weekend. This will feature several upper storm systems emanating
from the Pacific, bringing bouts of light to moderate valley rain
and moderate to heavy mountain snow at times.

We may see residual shower and mountain snow activity early
Wednesday as a fast moving upper storm departs. This will allow
modest ridging to build aloft, producing rather warm conditions for
late December. This trend will be short lived however, as another
fast moving storm approaches the Cascades during the late afternoon
and early evening hours, bringing a wave of valley rain and mountain
snow overnight Wednesday night through Thursday. Snow levels will
initially be quite high given the rising heights associated with the
ridge, but they should quickly fall late Thursday into early Friday,
when remnant snow showers will likely persist over the Cascades and
Blue Mountains. This should result in some snow accumulation with
the greatest amounts over the higher elevation of the Washington
Cascades. In addition to the potential for rain/snow, the pattern
would tend to favor strong and gusty winds over the foothills of the
Blue Mountains and in the Grande Ronde Valley ahead of the main
frontal push late Wednesday Night into Thursday. This system will
exit the region by early Friday, with a return to near normal
temperatures and drier conditions with overcast skies.

&&

.Aviation (06z TAFs)...Fog and low stratus will continue to impact
some terminals, especially KYKM and KDLS, where locally dense fog
has developed. Elsewhere, in the wake of yesterdays rains, some
patchy fog can be expected with brief impacts to visibilities. Winds
to remain light until late this afternoon through tonight, when
strong and gusty south winds develop ahead of a potent storm system
set to bring a good chance of rain to most terminals by the end of
the period.

Friday night through Sunday...A weak ridge is expected to build over
the area Friday night and Saturday with some mountain showers.
Models are struggling with the timing of the next system to move
through Saturday night through Sunday night, so have a slight chance
to chance pops through the period. It will bring much colder air
into the area with snow level falling to 500 feet along the east
slopes of the Washington Cascades to 3000 feet over central Oregon
and near 1500 feet over northeast Oregon. 93

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  51  44  56  39 /  10  90  70  50
ALW  52  45  55  42 /  20  90  90  60
PSC  51  43  55  42 /   0  90  70  10
YKM  45  38  49  35 /   0  80  80  50
HRI  51  43  55  39 /   0  80  60  30
ELN  41  35  45  34 /  10  90  90  60
RDM  49  42  55  34 /   0  50  70  70
LGD  45  38  44  36 /  40  70  90  80
GCD  45  38  48  34 /  10  70  70  70
DLS  48  41  50  39 /  10  80  90  80

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory from 10 PM this evening to 3 PM PST Tuesday for
     ORZ508-510.

     High Wind Watch from this evening through Tuesday afternoon for
     ORZ509-511.

     Winter Weather Advisory from 7 PM this evening to 10 AM PST
     Tuesday for ORZ502.

WA...Winter Weather Advisory from 7 PM this evening to 10 AM PST
     Tuesday for WAZ030.

&&

78/79/93