Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 180602 AAA
AFDPDT

Area Forecast Discussion...Updated
National Weather Service Pendleton OR
1002 PM PST Tue Jan 17 2017

Updated Aviation Discussion

.SHORT TERM...Evening Update...Precipitation associated with the
latest Pacific storm system continues to move across the region this
evening. The type of precip at any given location is very tricky to
forecast due to cold pools, the largest of these being over the
Columbia Basin, including the Yakima and Kittitas valleys, and the
Columbia Gorge. Warm air has spread over much of Deschutes and
Wheeler counties and is making good headway into Jefferson, Crook
and Grant counties. This warm air has also been moving through the
Blue Mountains, and is beginning to make appearances along portions
of the Blue Mountain foothills. Elsewhere across the region, warm
air aloft has spread north into eastern Washington. Thus we are
seeing rain, freezing rain, sleet and snow. Freezing rain has
locally accumulated to a quarter inch in the Gorge, the Yakima
valley and the Simcoe highlands. Thus the ice storm warnings in
these areas are on track. Elsewhere in the Columbia Basin there have
been reports of a light glaze at various locations. Winds remain
strong over the Grande Ronde valley, especially the south end, and
the high wind warning will be continued through tonight. Will
continue the other warnings and advisories for now. Low temps in
many of the cold pool areas will continue to rise through the night
due to downward heat transport by the precip or by mixing of warmer
air from aloft. Updates were made to adjust low temps to reflect the
cold start this evening at many locations. Also updated to extend
mention of sleet into the late evening. 90

.LONG TERM...Previous Discussion...An upper low offshore will push
several short waves and fronts across the region through Tuesday.
This will keep skies mostly cloudy with periods of snow and lower
elevation rain. Temperatures will be closer to normal levels with
highs in the 30s to mid 40s. Lows in the 20s to lower 30s. Could
have locally breezy south winds Sun and Mon.

&&

.AVIATION...06Z tafs...The latest Pacific system will affect all TAF
sites. Steadier precip will occur at KDLS, KYKM, KPSC, KALW and
KPDT. These sites remain within the Columbia Basin cold pool, thus
precip at these sites will be in the form of freezing rain and/or
sleet through tonight into Tuesday morning. Expect warm air to work
into these areas at some point between midnight and noon Tuesday.
KPDT and KALW will be first to mix out of the cold air, with KYKM
being the last site to mix. At this time am indicating KALW and KPDT
to mix out at 13 UTC and 16 UTC respectively. These two sites may
mix out earlier, with the possibility of the cold air returning for
awhile before completely mixing out. Expect only rain showers at
KRDM and KBDN as southerly flow will keep these locations above
freezing through the period. Winds at KRDM and KBDN will be breezy,
10 to 18 kts sustained, from the south. Similar winds are expected
at KALW and KPDT (more southeasterly in direction) when they mix
from the cold pool. Elsewhere winds will be less than 10 kts. 90

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  14  41  37  44 /  90 100  90  30
ALW  14  43  39  45 /  90 100 100  40
PSC  18  40  36  42 /  90  80  70  10
YKM  21  38  31  41 /  90  80  60  10
HRI  17  39  36  42 /  90  90  70  10
ELN  21  35  30  38 /  90  80  60  10
RDM  35  41  30  40 /  70  70  60  20
LGD  25  35  32  38 /  90  90  90  70
GCD  30  39  35  39 /  90  90  70  50
DLS  20  41  37  43 /  90  90  70  30

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 10 AM PST Wednesday for ORZ044-507-
     508-510.

     Ice Storm Warning until 6 PM PST Wednesday for ORZ041.

     Winter Weather Advisory until 6 AM PST Thursday for ORZ505.

     Winter Storm Warning until noon PST Thursday for ORZ502-503.

     Winter Storm Warning until 4 PM PST Thursday for ORZ050.

     Winter Storm Warning until 6 AM PST Thursday for ORZ506.

     High Wind Warning until 7 AM PST Wednesday for ORZ049.

     Wind Advisory from 7 AM Wednesday to 4 AM PST Thursday for
     ORZ049.

     Blizzard Warning until noon PST Thursday for ORZ049.

WA...Winter Weather Advisory until 10 AM PST Wednesday for WAZ029.

     Ice Storm Warning until 6 PM PST Wednesday for WAZ024-026-027-
     521.

     Winter Storm Warning until noon PST Thursday for WAZ030.

     Winter Weather Advisory until noon PST Wednesday for WAZ028.

     Ice Storm Warning until 6 AM PST Thursday for WAZ520.

&&

$$

90/94/90



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