Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 301132 AAA

Area Forecast Discussion...Update
National Weather Service Pendleton OR
432 AM PDT Sun Apr 30 2017

Updated Aviation Discussion

.SHORT TERM...Today through Tuesday...Today a weather system with a
strong cold front with tight pressure gradients behind it will move
across the forecast area. The tight pressure gradients will result
in strong winds in some portions of the CWA...but most of the CWA
will be at least breezy. The winds will be strongest in the Kittitas
Valley, the Simcoe Highlands, the eastern Columbia River Gorge and
in the Oregon Lower Columbia Basin. Have expanded the wind advisory
to include all these areas besides the previously issued wind
advisory for the Kittitas Valley. Winds will be from 30 to 40 with
gusts to 50 mph in these areas from 7 AM to 9 PM today. Elsewhere
most locations will have winds from at least 10 to 20 mph...but
likely 15 to 25 mph in most areas. There will be some rain and
higher mountain snow showers mainly this morning over the mountains.
Any precipitation amounts will be very light and mainly early this
morning as evident on the radar and satellite imagery. Tonight a dry
northwest flow will be over the forecast area ahead of an upper
ridge building over the Pacific. This high pressure ridge will move
eastward into the CWA on Monday. However mid and high level moisture
will move over the top of the ridge and into the CWA causing mostly
cloudy skies and perhaps a few light showers over the higher
mountains. Then on Tuesday the upper ridge will amplify and push the
moisture to the northeast with just partly cloudy skies over the
CWA. There will be a warming trend each day of the short term
forecast...except for Monday where temperatures will cool down from
Sunday due to dense mid and high clouds. On tuesday temperatures
will rebound quickly as skies begin to clear under the amplifying
high pressure ridge. 88

.LONG TERM...Tuesday night through Sunday...The extended period will
begin with an upper level ridge building over the area. A warm front
will push through the forecast area from the west Tuesday night into
Wednesday AM...this will usher in much warmer temperatures...but
could also bring some mid and high level clouds with it. By
Wednesday afternoon the ridge will be strong enough to keep
conditions dry, under mostly clear or partly cloudy skies. Highs
will reach the mid 70s to lower 80s Wednesday afternoon. The latest
model guidance is starting to converge on a more unified solution as
a deep upper level trough begins to approach the forecast area on
Thursday. The latest guidance has slowed the influence of the trough
slightly and think this trend may continue. For sensible weather
this will mean continued above average temperature on Thursday and
perhaps even into Friday. Highs on Thursday will be between 75 to 85
degrees for most locations....and should remain in the mid to upper
70s for Friday(especially east). A chance of showers and
thunderstorms will develop across much of the region starting either
late Thursday afternoon or Thursday evening and continue into
Friday. If the model guidance continues the trend of showing a
stronger upper level trough moving into the area it is plausible
that a few of the thunderstorms could be on the stronger side
Thursday evening and again on the storms will have
plenty of instability and wind energy to tap into. This potential
will be monitored closely in future forecast updates. For next
weekend the forecast area will remain under the influence of a broad
upper level trough. The overall weather pattern will become much
less progressive as blocking influences increase downstream. The
upper level trough/low that was impacting our weather on Friday will
only slowly move onto the west coast and then likely slowly to the
south...toward California. This will keep the chance of showers in
the forecast, especially along the East Slopes of the Cascades and
across much of Central/Northeast Oregon. Temperatures should see a
cooling trend...running closer to the seasonal average. This should
allow highs to reach the 60s or lower 70s...with overnight lows
cooling into the 30s and 40s once again. 77


.AVIATION...12z TAFs...VFR conditions are forecast to prevail at all
terminals in the forecast area over the next 24 hours. A weather
system is bringing sct to bkn mid level clouds mainly between 4k to
8k ft agl to the area this morning. Light rain showers are also
falling INVOF KPDT and esp KALW. Showers will taper off and end by
daybreak with clouds decreasing and becoming few to sct through the
day. Skies will be mostly clear this evening and through the
overnight hours with just a few/sct mid and high level clouds around.

Winds will increase quickly and significantly later this morning (15-
18z) behind a departing cold front. Westerly winds between 15 to 25
kts are expected at most locations...with gusts up to 30-35 kts at
times....especially at KDLS and KPDT. Winds will peak in the early
to mid-afternoon hours before gradually diminishing toward evening.
Winds will decrease to mainly AOB 12 kts after 01/04-08z. 77


PDT  61  37  59  41 /  30   0  10  20
ALW  65  42  62  45 /  40  10  10  20
PSC  66  39  65  40 /  10   0  10  10
YKM  64  37  62  40 /   0  10  10  10
HRI  65  38  63  42 /  10   0  10  10
ELN  58  37  58  38 /  10  10  10  10
RDM  59  29  59  38 /  20   0  20  10
LGD  59  36  57  40 /  50  10  20  20
GCD  60  33  57  39 /  30  10  20  20
DLS  61  41  62  44 /  20  10  20  10


OR...Wind Advisory from 7 AM this morning to 9 PM PDT this evening
     for ORZ041-044.

WA...Wind Advisory from 7 AM this morning to 9 PM PDT this evening
     for WAZ024-026-521.



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