Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 270957
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
257 AM PDT SAT AUG 27 2016

.SHORT TERM...Today through Monday Night...A broad trough covers
much of Canada and the US this morning with a ridge out in the
Eastern Pacific. Satellite imagery clearly shows an upper low in the
Canadian Rockies moving through the trough. This low will push a dry
cold front through the area later today. While there will be some
increase in cloudiness in the Washington portion of the area, no
precipitation is expected. The main impact will be breezy to windy
conditions late this morning through this evening in the Columbia
Gorge, Columbia Basin and adjacent valleys. West to northwest winds
of 15 to 30 mph are expected there this afternoon and early evening
with 10 to 20 mph winds elsewhere. Winds will decrease in the
evening. Temperatures today will be similar to yesterday and with
humidity remaining low, fire weather concerns will be high. A Red
Flag Warning remains out for the the Columbia Gorge, Columbia Basin
and surrounding valleys this afternoon through this evening. A more
detailed discussion of the the fire danger can be found in the fire
weather discussion below. Tonight the upper low will move east into
Central Alberta while the front will remain hung up along the Blue
Mountains and will gradually dissipate through Sunday morning.
Partly cloudy skies will continue over the Washington portion of the
area while the Oregon portion will be mostly clear. This will help
keep low temperatures tonight in the upper 50s to mid 60s in the
north while the mountains and the south will be in mid 40s to mid
50s. Sunday and Sunday night another upper low will move south along
the British Columbia coast and deepen the trough offshore. The upper
flow will turn more southwesterly but temperatures will cool a few
degrees as cooler air moves into the area. Skies will become mostly
clear and winds will remain light with no precipitation expected. On
Monday and Monday night, circulation around the trough will help
build a ridge over the Rockies. While we will be on the western
fringe of the ridge, rising heights will help warm us back to the
mid 80s to lower 90s in the lower elevations and into the 80s in the
mountains. Perry

.LONG TERM...Tuesday through Saturday...A shortwave trough will move
NEWD across eastern Oregon Tuesday afternoon and evening. There may
be just enough instability and forcing for a few thunderstorms until
mid evening. For Wednesday and Thursday the models have trended much
drier compared to previous runs with just weak troughing over the
area. There will likely be some cloud cover and cooler temperatures
with highs of 80-85 in the lower elevations. As a large-scale trough
consolidates over the western U.S. on Friday there will be a better
chance for showers areawide. Instability parameters look weak on
Friday except for over Wallowa County so the thunderstorm threat
appears rather limited. The thunderstorm potential will increase on
Saturday...especially in the afternoon and evening with the trough
overhead. Some locations could see decent amounts of rainfall
depending on where the showers tend to concentrate. It will be cool
Friday and Saturday with highs mainly in the 70s lower elevations
and 60s in the mountains.

&&

.AVIATION...12Z TAFS...VFR conditions will prevail through the
forecast period with just a few high clouds expected. West winds
will be the primary concern this afternoon and evening. Winds will
increase to 15-25 kt with some higher gusts after 18Z before
diminishing around 03z. 78

&&

.FIRE WEATHER...Previous discussion...A change in the weather
pattern will also mean fire weather will be more active today and
again on Tuesday. The upper level trough and its associated cold
front will track across British Columbia and northern Washington
tomorrow. The Fire Weather Watches that were in effect for the Lower
Columbia Basin, the Yakima Valley, the Eastern Columbia River Gorge,
and the Blue Mtn Foothills have been upgraded to Red Flag Warnings
in effect from 1 PM-9 PM Saturday for gusty winds and low humidity.
Fire weather concerns will shift from the wind/RH threat to a threat
of thunderstorms Tuesday (details can be found in the long-term
discussion). The last time our forecast area observed thunderstorms
was August 10...so this is the first time in over two weeks that new
fire starts with lightning will be addressed.  There is a
possibility of wetting rain with some storms...but this does not
appear to be a big rain producer for most of our area.  Wister

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  89  60  85  59 /   0   0   0   0
ALW  91  66  86  65 /   0   0   0   0
PSC  93  60  88  59 /   0   0   0   0
YKM  91  58  88  57 /   0   0   0   0
HRI  92  61  87  59 /   0   0   0   0
ELN  86  58  86  56 /   0   0   0   0
RDM  89  49  89  49 /   0   0   0   0
LGD  89  54  87  53 /   0   0   0   0
GCD  89  54  87  54 /   0   0   0   0
DLS  90  64  88  61 /   0   0   0   0

&&

.PDT Watches/Warnings/Advisories...
OR...Red Flag Warning from 1 PM this afternoon to 9 PM PDT this
     evening for ORZ639-641.

WA...Red Flag Warning from 1 PM this afternoon to 9 PM PDT this
     evening for WAZ639-641-675.

&&

$$

83/78/78/85



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