Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 271559 AAA
AFDPDT

Area Forecast Discussion...Updated
National Weather Service Pendleton OR
859 AM PDT TUE SEP 27 2016

Updated product formatting to move the updated AVIATION Discussion
for the 18Z TAFs out of the PREVIOUS DISCUSSION block and place it
immediately below the SHORT TERM UPDATE Discussion.

.SHORT TERM UPDATE...Today...A weak mid/upper level shortwave is
moving across British Columbia this morning as it rides over the
longwave ridge over the Pacific Northwest. Other than increasing
the onshore flow in the boundary layer today, the shortwave will
not be a factor in today`s weather, other then producing a tad
stronger winds of 13-20 mph in the Kittitas Valley and the
eastern Columbia River Gorge this morning along with scattered
mid and high level clouds this afternoon over central and
southeast WA with central and NE Oregon remaining sunny through
this afternoon. I increased max temps for today by a few degrees
in the Lower Columbia Basin and at Hermiston and Pendleton.
Otherwise, I made no other changes to the forecast for today.
Polan

&&

.AVIATION...18Z TAFs...Increasing mid/high level clouds this
afternoon and overnight resulting in SCT 15000-20000 ft AGL as a
weak frontal boundary moves through the area. Winds will be
increasing to 7-15 kts after 18Z and then becoming light and
variable overnight. 93

&&

.PREVIOUS DISCUSSION... /issued 300 AM PDT TUE SEP 27 2016/

SHORT TERM...Today through Thursday...A weakening Pacific
disturbance will continue to move into and over the upper level
ridge over the western U.S. today. This disturbance will have a
limited impact on the weather conditions across the Pacific
Northwest through tonight. Will see a few mid and high level clouds
drift across the area today and tonight. Any precip will be limited
to Cascade crest area in extreme western Kittitas County in
central Washington. Will see some increased west and northwest
winds with the strongest winds occurring in the Gorge and the
Kittitas valley. High temps will continue to run 5 to 10 degrees
above seasonal, though a bit cooler than yesterday due to the
increasing onshore flow. An upper level trough is still expected
to develop over the Gulf of Alaska Wednesday and then sink
southeast towards the PACNW Wednesday night and Thursday. This
will cause the flow aloft to shift from west-southwesterly
Wednesday to southwesterly Thursday. Initially moisture will be
limited and expect fair and dry conditions Wednesday. Temps will
cool some between the Blue Mountains and the Cascade crest
Wednesday, but will continue warm (similar to today) south and
east of the Blues. Cooling will begin to shift into these areas
Thursday due to increased moisture and cloud cover. There should
be enough instability for the development of a few showers
Thursday afternoon over the Blue and Wallowa Mountains. At this
time instability looks too weak for any thunderstorms in these
areas. 90

LONG TERM...Thursday night through Monday...An offshore upper level
trough will deepen Thursday night and Friday. This will increase
southerly flow over WA and OR and transport moisture and instability
into the CWA. Friday and Saturday the trough will shift east. This
will bring higher pops and cooler temperatures to WA and OR next
weekend. A series of disturbances will rotate through the trough
bringing showers...cooler temperatures...and lowering snow levels to
5000-6000 ft Saturday night through Monday. Coonfield

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  88  49  80  50 /   0   0   0   0
ALW  85  55  80  57 /   0   0   0   0
PSC  86  50  81  50 /   0   0   0   0
YKM  85  47  81  46 /   0   0   0   0
HRI  88  49  81  49 /   0   0   0   0
ELN  81  46  80  47 /   0   0   0   0
RDM  83  40  81  41 /   0   0   0   0
LGD  85  44  82  47 /   0   0   0   0
GCD  86  45  84  46 /   0   0   0   0
DLS  81  52  81  52 /   0   0   0   0

&&

.PDT Watches/Warnings/Advisories...
OR...None.
WA...None.
&&

$$

99/93/90/76



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