Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 170950

Area Forecast Discussion
National Weather Service Pendleton OR
250 AM PDT Mon Jul 17 2017

.SHORT TERM...Today through Wednesday...A west to southwest flow
aloft will persist today with dry and stable conditions. Pressure
gradients will be weaker today for less wind. This will allow
temperatures to warm up a degree or two...but it will remain cooler
than normal today. Then on Tuesday an upper ridge will begin to
amplify over the inland Northwest with the flow over the CWA
becoming more southwest. A weak disturbance in the flow will bring
some increase in moisture and instability to eastern areas of the
CWA. Have added a slight chance of afternoon and evening showers and
a thunderstorm or two over the central to the northeast mountains.
Moisture will be very limited so am only expecting only very light
amounts of precipitation. Elsewhere it will remain dry. Heights and
850 mb temperatures will increase with the building ridge, and the
southwest flow, a warming trend will begin. Temperatures will rise
to the mid 80s to lower 90s in the lower elevations, which is near
normal. Dry and stable conditions will return on Wednesday. However,
there will be another disturbance in the flow on Wednesday
afternoon. Moisture will be too limited to warrant any mention of
precipitation or thunderstorms for least for now.
Temperatures will continue to warm by a couple to a few degrees with
maximum readings in the upper 80s to lower 90s in the lower
elevations and mostly 80s in the mountains.  88

.LONG TERM...Wednesday Night through Monday...Wednesday night an
upper low and trough will be approaching the Pacific Northwest coast
then will move into Southern British Columbia Thursday and into
Alberta Thursday night. Models, especially the GFS, show increasing
moisture over the Washington portion of the area but little if any
precipitation except perhaps along the Washington Cascade Crest
Thursday afternoon. Believe that we will just see cloudiness, so
have kept a dry forecast for now, but did increase pops along the
Cascades. Winds should increase with the trough passage to 10 to 20
mph Thursday afternoon and 20 to 30 mph in the Columbia Gorge and
Kittitas Valley. A generally flat westerly flow will develop Friday
with sunny and dry weather with light winds expected. Models bring a
weak disturbance in after that, Friday night in the GFS and Saturday
in the ECMWF and Canadian models. Only the GFS develops any
precipitation and keeps it up near the Canadian border. The main
impact will be a slight increase in winds to 10 to 15 mph and partly
cloudy skies. Saturday night through Sunday night models build a
ridge over the area but vary as to the strength and location. It
should be a fair and sunny period. On Monday a trough approaches the
coast and pushes the ridge off into Idaho and Montana. The GFS shows
some moisture over the eastern Oregon mountains in the afternoon but
no precipitation while the ECMWF and Canadian keep clear skies over
the area. Will keep a dry forecast for now but suspect the eastern
Oregon mountains may end up with a few showers and thunderstorms
next Monday afternoon. Temperatures will be in the upper 70s and 80s
on Thursday and then warm a degree or two each day, ending up in the
mid 80s to mid 90s by Monday. Perry


.AVIATION...12Z TAFs...VFR conditions will continue for the next 24
hours with mainly clear skies. Winds will generally be less than 10
kts though KDLS, KRDM and KBDn may reach 15 kts from 20Z-03Z this
afternoon. Perry


PDT  82  51  88  57 /   0   0   0   0
ALW  84  55  90  61 /   0   0   0   0
PSC  86  52  92  58 /   0   0   0   0
YKM  85  52  89  57 /   0   0   0   0
HRI  85  52  91  59 /   0   0   0   0
ELN  81  50  86  55 /   0   0   0   0
RDM  82  43  86  47 /   0   0  10  10
LGD  82  45  85  52 /   0   0  10  10
GCD  86  46  87  51 /   0   0  20  10
DLS  85  54  88  59 /   0   0   0   0





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