769
FXUS66 KPDT 110539
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1039 PM PDT Sun Aug 10 2025

.AVIATION...06Z TAFs...Low aviation concerns the next 24-hrs with
VFR prevailing. Largely clear scene on satellite outside some
high clouds working south owing to a weak subtle shortwave trough
moving into the far Northern Intermountain West. General light,
diurnal wind regime with weak cross-Cascade gradient with highest
speeds seen in the afternoon, 5-10 kts, at TAF sites. Largely
clear skies. Small wildfire near KRDM, Canal Fire, continues to be
reported at ASOS this evening. However, restrictions in
visibility are not anticipated owing to favorable wind direction
which should limit smoke transport towards the terminal but bears
watching nonetheless.

&&

PREV DISCUSSION... /issued 108 PM PDT Sun Aug 10 2025/

DISCUSSION...
Strong high pressure will build over the Pacific Northwest today
and remain over the area through Monday before getting pushed
southward on Tuesday. By later Tuesday a more zonal westerly flow
will move into the region and remain for the rest of the week.

The ridge of high pressure will bring very hot temperatures to the
area, beginning today and peaking Monday and Tuesday. Extreme heat
warnings are in effect and most lower elevation locations will be
in moderate HeatRisk today. Moderate HeatRisk becomes more
widespread Monday and Tuesday with portions of the Columbia
Basin, Blue Mountain Foothills, Yakima and Kittitas Valleys,
Columbia Gorge and and central Oregon reaching Major HeatRisk.

High temperatures could top out in the 102-103 range in the
hottest locations. These would be about 15 degrees above normal.
The ECMWF EFI does key in on the temperatures, with values mainly
in the 0.7 to 0.8 range, especially across the Basin.

After Tuesday, we will see a gradual cool down, with Wednesday
being about 10 degrees cooler than Tuesday (but still above
normal) and Thursday through the remainder of the period having
high temperatures near seasonal levels, generally in the 80s.

Winds are expected to increase as the ridge breaks down Tuesday
and continue into Wednesday. It will be breezy to windy,
especially later Tuesday into Wednesday, with breezy conditions
continuing into Thursday. Low RH values, especially on Tuesday and
Wednesday will lead to enhanced and possibly critical fire
weather concerns. The lower temperatures Thursday onward will help
raise humidities and lower winds after Thursday will also help
decrease concerns beyond then. The ECMWF EFI is picking up the
increased winds on Wednesday, especially across the Columbia
Basin and Foothills of the Blue Mountains, with values of 0.7 to
0.8, mainly.

No precipitation is expected until Friday into Saturday, and then
only over the mountains.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  64  99  65  99 /   0   0   0   0
ALW  70  99  71 100 /   0   0   0   0
PSC  65 101  66 102 /   0   0   0   0
YKM  66  99  69 101 /   0   0   0   0
HRI  65 102  66 102 /   0   0   0   0
ELN  65  97  66  97 /   0   0   0   0
RDM  56  99  58  99 /   0   0   0   0
LGD  60  97  62  98 /   0   0   0   0
GCD  60  98  63 100 /   0   0   0   0
DLS  71 103  72 100 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Extreme Heat Warning until 10 PM PDT Tuesday for ORZ041-044-505-
     507-508-510-511.

WA...Extreme Heat Warning until 10 PM PDT Tuesday for WAZ024-026>029-
     521.

&&

$$

SHORT TERM...77
LONG TERM....77
AVIATION...80