Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 230358
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
858 PM PDT Sun Oct 22 2017

.UPDATE...The latest satl was showing an area of clouds over our
ne forecast area and this was moving away from the region. Drier
conditions and clearing skies can be expected overnight. Some
patchy fog is possible across the lower lying areas of the basin
that includes the gorge. Otherwise low temps can be expected in
the 40s except 30s in the mountains.

&&

.AVIATION...vfr conditions will persist at all taf sites for the
next 24 hours. However taf sites kdls and kpsc could experience
patchy fog between 10z and 15z that may reduce vsby to 4 or 5
miles.

&&

.PREV DISCUSSION... /issued 426 PM PDT Sun Oct 22 2017/

SHORT TERM...Tonight through Wednesday...An upper level trough will
be exiting to the east overnight allowing a ridge of high pressure
to build over the region through the first of the week. There will be
a few lingering showers over the mountains through this evening but
then showers end by midnight. Breezy conditions will also persist
into the evening and then decrease overnight generally becoming
light. Could see some patchy fog develop late tonight through early
Monday in some low lying areas around the Columbia basin but this
depends on winds ending and the amount of lingering cloud cover. Fog
will become more likely Monday night and Tuesday night under clear
skies and high pressure induced shallow or surface based inversions
forming. High pressure Monday and Tuesday will bring warmer and dry
conditions back to the forecast area. However, as mentioned, there
will be inversions to deal with which will cause slow or delayed
heating around the Columbia Basin resulting in a cool air pool in
the Basin. This will hold max temperatures down a little but above
the inversions temperatures will be warm.

The ridge of high pressure will last through Tuesday but then
suddenly collapses and shifts to the west. This will allow a cold
front to drop into the area on Wednesday in a northwest flow.
Precipitation will be limited with this system and mainly confined
to the Washington Cascades and over northeast Oregon and southeast
Washington.

The areal flood warning continues for the Yakima River in the Elk
Meadows subdivision between Cle Elum and Easton in Kittitas County
until 7pm. River gages show that the Yakima River near Easton is
close to cresting at this time. It is expected to begin to recede
this late this afternoon or evening.

LONG TERM...Wednesday Night through Sunday...Wednesday night a
system and trough will be moving through the area with a slight
chance of showers along the Cascade crest and a chance of rain from
the Blue Mountains eastward. Models have some timing differences so
have kept the showers going through the night. Rain amounts will be
fairly light and snow levels will be around 9000 feet so snow is not
expected to be a problem. Lower elevations will be dry. Winds will
reach 10 to 15 mph during the evening. On Thursday, the front and
trough will move off to the east and an offshore ridge will expand
over the area. The ridge will move overhead on Friday and remain
through the weekend though it will weaken on Sunday. This will give
us fair and dry weather with mostly clear skies and light winds
Thursday through Sunday. High temperatures will be in the mid 50s
through lower 60s each day. Lows will mainly be in the 30s with a
few lower 40s in the lower elevations and a few upper 20s in the
higher mountains valleys. Perry

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  45  64  38  63 /   0   0   0   0
ALW  46  64  39  64 /   0   0   0   0
PSC  42  64  36  60 /   0   0   0   0
YKM  38  61  34  62 /   0   0   0   0
HRI  43  64  35  62 /   0   0   0   0
ELN  39  60  33  60 /   0   0   0   0
RDM  37  66  33  69 /  10   0   0   0
LGD  41  59  36  66 /  10   0   0   0
GCD  38  62  35  70 /  20   0   0   0
DLS  44  67  41  65 /  10   0   0   0

&&

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

$$

97/97



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