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Area forecast discussion...updated aviation discussion 
National Weather Service Pendleton or
1020 PM PDT Friday may 22 2015

Update...one last area of stronger thunderstorms are moving
through northern Benton County at this time as other showers and
thunderstorms are ending. Large upper trough remains over the west
with wrap around moisture over Oregon and next upper level low is
moving south over Vancouver Island and will continue into the area
overnight. I expected thunderstorms to end...but some showers will
continue over the eastern portions of the forecast area through
morning. 93

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Previous discussion... /issued 400 PM PDT Friday may 22 2015/

Short term...tonight through Sunday night...low pressure to the
south was pushing abundant moisture north and into the two state
area this afternoon that will persist into this evening with showers
and thunderstorms expected. Precipitable waters were around an inch and some
thunderstorms will continue producing heavy rain especially in the
Flash Flood Watch areas that include along the east slopes of the
Washington Cascades and over the blue/Wallowa/John Day Highlands. In
addition hail will be possible with the strongest storms. The storms
will decrease after sunset and the bulk of the precipitation should be over
the central portions of the area toward morning. Another round of
showers/thunderstorms and rain are expected to develop and expand in coverage Saturday
afternoon and continue into Saturday night. As the low drifts away
from the region drier air will move into the two state area Sunday.
However a disturbance is forecast to move across the area Sunday
afternoon that will combine with daytime heating to produce showers and
isolated thunderstorms and rain again over portions of the region into Sunday night.

Afternoon temperatures will be near normal Saturday with a warming trend
expected into Sunday.

Long term...Memorial Day through Friday. Models are in better
agreement but continue to have discrepancies on the placement of the
upper low moving south across Washington/or early in the period. In
general...there will be a slight chance to a chance of showers and
thunderstorms on Memorial Day through Tuesday. This could continue
into Wednesday depending if the GFS and Canadian verify which keep
the low east of the Cascades unlike the European model (ecmwf) which pushes it
eastward. Models have a history of poor placement of closed lows
and tend to force lows out of the region too fast. Keeping this in
mind...will follow the slower solutions of GFS/Canadian. The long
duration of the broad upper level trough and cyclonic flow may
finally transition to a drier ridge pattern by the end of the work
week. Will lower probability of precipitation and keep above seasonal temperatures in the
forecast by Friday. Wister

Aviation...06z tafs. VFR conditions will prevail over the next 24
hours. Scattered-broken clouds with ceilings 050-080 above ground level will continue overnight
with some light rain. There continues to be some isolated thunderstorms
along the Blue Mountain foothill from kpdt to kalw through 08z.
Additional showers and isolated thunderstorms are possible mainly over the
mountains on Saturday. Westerly winds will continue at 15 to 25 knots
at the kdls. 93

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Preliminary point temps/pops...
PDT 54 75 51 73 / 60 40 20 10
alw 56 77 55 77 / 60 40 20 10
psc 58 82 54 82 / 50 40 10 10
ykm 59 81 55 81 / 40 40 10 10
hri 57 80 53 78 / 50 40 10 10
eln 56 80 54 80 / 30 40 20 10
rdm 44 70 39 72 / 20 20 10 10
lgd 54 70 50 70 / 70 40 30 30
gcd 49 71 45 72 / 70 30 20 10
dls 57 70 54 79 / 20 20 10 10

&&

PDT watches/warnings/advisories...
or...Flash Flood Watch until 9 PM PDT this evening for orz049-050-502-
503-505-506.

Washington...Flash Flood Watch until 9 PM PDT this evening for waz030-520.

&&

For additional weather information, check our web site at...
www.Weather.Gov/Pendleton

$$

93/85/93

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