Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 312236 AAA
AFDPDT

Area Forecast Discussion...Updated
National Weather Service Pendleton OR
335 PM PDT TUE MAY 31 2016

Updated aviation discussion

.SHORT TERM...Tonight through Friday...The ridge of high pressure
over the region will continue overnight and into Wednesday with even
warmer temperatures expected. Then an upper level trough passing
through western Canada will begin to flatten the ridge late
Wednesday and into Thursday. This will begin to generate breezy west
winds Wednesday afternoon along portions of the east slopes of the
Cascades and then spill out into the Columbia Basin by the evening
generating some fire weather concerns. It will also generate some
weak instability over northeast Oregon leading to a slight chance of
some thunderstorms mainly over Union and Wallowa counties. Breezy
conditions and slightly cooler temperatures are expected Thursday
under the flat ridge pattern. The ridge will begin to amplify over
the region again on Friday and continue over the weekend.
Temperatures will begin to warm on Friday leading to the very hot
temperatures expected through the weekend.

.LONG TERM...Friday night through Tuesday...High pressure will
continue to dominate the area over the weekend.  As a result expect
hot any mostly dry conditions.  A low pressure system to the south
will swing across the central California coast and spin up moisture
to central and possibly northeast Oregon.  This low was previously
projected to be further north and to possibly swing across eastern
Oregon. The changes have impacted thunderstorm probabilities and
coverage significantly.  Overall...There will be decent instability
over the central and northeast Oregon mountains but this is expected
to be capped, and therefore the chances of thunderstorms on Saturday
look minimal to nil.  Sunday and Monday have added a slight chance
of thunderstorms to the central Oregon, but still keeping northeast
Oregon capped without thunderstorms mentioned.  By Tuesday there may
be enough moisture and instability to get thunderstorms over central
and northeast Oregon, so have added thunder to the forecast for
these areas.

Temperatures will be hot. Expect highs to be 90s to lower 100s
across the lower elevations with 80s to lower 90s for the mountains.
Right now models are back and forth as to if Sunday or Monday will
be the hottest day.  For now will continue with Sunday being the
hottest day.  But, if the ridge holds together a little longer as
some models indicate, then expect Monday could be another hot day if
not the hottest day. Weber


&&

.AVIATION...00Z TAFS...VFR conditions will prevail for the next 24
hours. Scattered high clouds 15-25KFT through 112-15z, with few to
scattered mid level clouds there after.  Winds will generally remain
below 10 KTS through 15z with some TAF site gusting 10 to 20 KTS
thereafter. Weber

&&

.FIRE WEATHER...A weak shortwave will initiate a marine push on
Wednesday. Westerly winds will increase and become gusty during the
afternoon and evening. Temperatures will be in the 80s, which is
well above normal for this time of year. Relative humidity will be
less than 20 percent in many areas. Any new or existing wildfires
could potentially spread very rapidly, especially in the lower
elevations and fine fuels, which include grass and brush. Red Flag
Warnings have been issued for Zone 675 and most of Zone 641 in the
Columbia Basin, and portions of Zone 639, which includes the Eastern
Columbia River Gorge. Warnings have also been issued for the lower
elevations along the East Slopes of the Oregon Cascades in eastern
portions of Zones 610 and 611, and western portions of Zone 640 in
Central Oregon. The warnings will be in effect 2 PM through 9 PM
Wednesday. Breezy winds can also be expected on Thursday, but
relative humidity will be higher.  Cobb


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  50  88  58  81 /   0   0   0   0
ALW  55  88  62  81 /   0   0   0  10
PSC  51  91  62  85 /   0   0   0   0
YKM  53  89  59  82 /   0   0   0  10
HRI  51  89  60  84 /   0   0   0   0
ELN  50  85  56  75 /   0   0  10  10
RDM  46  85  50  81 /   0   0   0  10
LGD  47  83  53  77 /   0  20  20  10
GCD  46  87  52  81 /   0  10   0  10
DLS  55  86  61  82 /   0   0  10  10

&&

.PDT Watches/Warnings/Advisories...
OR...Red Flag Warning from 2 PM to 9 PM PDT Wednesday for ORZ610-611-
     639>641.

WA...Red Flag Warning from 2 PM to 9 PM PDT Wednesday for WAZ639-641-
     675.

&&

$$

91/89/89



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