Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 301141 AAA

Area Forecast Discussion...Updated
National Weather Service Pendleton OR
440 AM PDT FRI SEP 30 2016

Updated aviation discussion

.SHORT TERM...Today through Sunday...Broad swly flow regime will be
over the area into Saturday as an upper low becomes established off
the pacnw coast. The low will move inland south of the area on
Sunday. An apparent weak impulse embedded in the flow resulted in
scattered showers and isolated thunderstorms yesterday evening into
early this morning. The latest GFS continues to suggest that a few
showers will be possible through the day across the middle of the
forecast area. For now will keep 15-20 percent pops going but
overall confidence in much occurring is low. There is a bit of
instability progged over Wallowa County this afternoon and evening
but again confidence that thunderstorms will actually form there is
low. Will let next shift analyze the 12 UTC models to see if t-
storms are worthy of inclusion in the forecast.

Otherwise a stronger trough will move across the area on Saturday
but moisture is not much shower activity is expected.
It will be a bit cooler with highs mainly in the 60s lower
elevations. There will be a bit of a sw-w breeze in the afternoon.
Saturday night will be one of the cooler nights of the fall so far
with lows in the 20s mountains and 35-42 lower elevations. On Sunday
with the upper low dropping south of the area there will be a chance
for showers mainly across central Oregon. 78

.LONG TERM...Sunday night through Friday...Sunday night an upper
low will be moving through Northern California and Nevada. There
will be a chance of showers mainly over Central Oregon and the
Ochoco-John Day Highlands in the evening tapering off overnight. The
low will continue moving east on Monday and a generally fair and
partly cloudy day is expected. Another system is expected to arrive
late Monday night or Tuesday though models differ as to the strength
of the system. The GFS has a wet system arriving early on Tuesday
and bringing rain to most of the area. The ECMWF and Canadian are
slower and much drier with this system. Have split the difference
and have a slight chance of rain in the Cascades, Central Oregon and
the Eastern Oregon mountains on Monday night and Tuesday. Tuesday
night through Wednesday night a generally westerly flow with no
significant disturbances will be over the area and it should be fair
and dry aside from a slight chance of showers along the Cascade
Crest. Thursday through Friday models show a trough crossing the
area though they differ as to the timing. Have kept a slight chance
of showers across the area for now through this period and will zero
in on the timing as models come into better agreement. Temperatures
will remain cool and mainly in the 60s with 50s in the mountains.
Low temperatures will be mainly in the 40s and lower 50s with upper
20s and 30s in the mountains. Perry


.AVIATION...12Z TAFS...VFR conditions are expected to prevail across
the area for the next 24 hours. There will be ample mid and high
level clouds as an upper level trough pushes into the area. SCT to
BKN clouds between about 9K to 25K FT AGL are expected much of
today. There will also be a few weak shra around through early this
afternoon...possibly affecting all TAF sites...but the probability
of measurable precipitation is low enough that I have confined
mention to just the next few hours at KDLS and will amend as
necessary. After 00Z, clouds will increase and lower to 7K to 12K
AGL though showers are not expected. Winds will generally remain
below 15 kts though KDLS will reach 10 to 20 kts with gusts to 25
kts from 19Z to 03Z and KRDM and KBDN will have gusts to 20 kts from
21Z to 03Z. Perry


PDT  74  47  66  38 /  20  10  10  10
ALW  75  51  67  43 /  20  10  10  10
PSC  77  50  70  41 /  20  10  10  10
YKM  73  41  66  38 /  10  10  10  10
HRI  77  47  70  40 /  20  10  10   0
ELN  70  42  63  37 /  10  10  10  10
RDM  70  31  60  31 /  10  10  10  10
LGD  75  43  64  33 /  10  20  10  10
GCD  76  41  64  27 /  10  10  10  10
DLS  71  48  67  44 /  10  10  30  10


.PDT Watches/Warnings/Advisories...


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