Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 200618

Area Forecast Discussion
National Weather Service Pendleton OR
1018 PM PST Sun Nov 19 2017

Updated the aviation discussion

.UPDATE...Snow was continuing along the east slopes of the
washington cascades and spotters were reporting up to three
inches of snow west of Roslyn with motorists spinning out on the
interstate. Web cams were showing the snow had expanded to the
east and into Cle Elum where temperatures hover around the
freezing mark. Thus the winter weather advisory will continue for
the east slopes of the washington cascades tonight with total
accumulation between 3 to 5 inches before mixing with and changing
to rain overnight. Motorists along interstate 90 west of Cle Elum
will experience snow packed and slippery roads.

Otherwise the storm system will bring rain to the entire region
overnight. A pocket of freezing temps remained around eln and
isolated locations could receive some freezing rain before warmer
air arrives tonight. Also advisory level winds persist in ladd and
pyles canyon.

Pops and weather and snow amounts and temps etc were modified and
the present short term forecast appears more on track.

.AVIATION...areas of mvfr conditions will develop tonight for all
taf sites and lcl ifr conditions are possible. A storm system will
bring rain to the area along with wind gusts to 25 kts into Monday.
After 18z the pcpn is expected to decrease at taf sites
kykm...kdls...kpsc and wind gusts to 30 kts are possible.
Elsewhere lcl mvfr conditions are expected along with wind gusts
to 30 kts.

PREV DISCUSSION... /issued 658 PM PST Sun Nov 19 2017/

UPDATE...Latest satellite and cams are showing snow falling near
the crest west of Cle Elum and have updated the area to reflect
this. Some colder air around freezing remains and the snow was
accumulating on roadways and the interstate and minor
accumulations were added for this evening. Around 1 to 3 inches.
Still expect the snow to eventually mix with and change to rain
toward midnight as snow levels rise. Otherwise the pcpn will track
east into the remainder of the area overnight and the present
short term forecast appears on track for now.

PREV DISCUSSION... /issued 323 PM PST Sun Nov 19 2017/

SHORT TERM...Tonight through Tuesday...A weak Pacific system will
push a weak, but wet, cold front into the region tonight. Precip
will begin over western Kittitas county within the hour. Precip will
gradually spread east and southeast to affect most of southeast
Washington, and northeast and central Oregon tonight. Snow levels
will initially run between 4000 and 5200 feet this evening, with the
lowest levels over our Washington zones. Snow levels are expected to
rise overnight, with most areas seeing levels above 5000 feet. Fog
and stratus lingered in the Kittitas valley all day and high temps
only made it to the mid 30s. Thus expect low temps to briefly fall
to around 32 at the time precip starts, and should see a mix of rain
and light freezing rain. Temps in this area should slowly warm
through the night so the freezing rain threat should end by late
evening. Elsewhere expect low temps (most above 32) to occur before
precip starts as well, then rise through the night. Winds will be
breezy to locally windy over central Oregon, portions of the Yakima
valley, the Grande Ronde valley and the mountain ridges. Pressure
gradients will support very windy conditions in the southern Grande
Ronde valley and have issued a wind advisory. Varying chances of
precip will continue over the region Monday and Monday night as the
front is expected to stall over the area. Snow levels will remain
relatively high, though they will fall to around 2800 feet over
Kittitas county Monday evening. Snow levels will rise areawide late
Monday night and Tuesday as the old cold frontal boundary moves
north into northern Washington. Precip will become widespread
Tuesday as this front moves north. 90

LONG TERM...Tuesday Night through Sunday...Models are in fairly
good agreement during the extended forecast period. There will be a
broad upper level ridge over WA and OR with a moist flow as multiple
weak Pacific systems move through the ridge. A warm front will move
north Tuesday night with widespread rain. Snow levels will be over
9000 feet Tuesday night through Thursday. More disturbances will
keep varying chances of rain Wednesday through Thursday. A cold
front will move through Thursday afternoon or evening. Precipitation
will decrease early Friday behind the front. Snow levels will come
back down to around 4000-6000 feet Friday. Another front will move
through Saturday night and Sunday with more rain. Temperatures will
remain above normal for this time of year. It will be breezy to
windy along the ridge tops with gusty south winds Thursday and
Friday. Coonfield


PDT  44  55  46  57 /  70  50  20  70
ALW  48  57  48  57 /  70  70  20  80
PSC  43  57  44  52 /  50  40  20  80
YKM  36  55  40  48 /  60  40  20  80
HRI  43  56  45  54 /  50  40  20  60
ELN  32  48  38  44 /  70  40  20  80
RDM  37  56  44  57 /  50  80  40  40
LGD  39  51  43  52 /  80  80  40  70
GCD  38  51  43  54 /  60  70  30  60
DLS  36  54  44  54 /  70  70  30  70


OR...Wind Advisory until 10 AM PST Monday for ORZ049.

WA...Winter Weather Advisory until 2 AM PST Monday for WAZ520.



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