134
FXUS66 KPDT 300519
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1019 PM PDT Mon Jun 29 2026

.KEY MESSAGES...
- Breezy and below normal temperatures through mid-week.

- Warmer and drier trend Thursday, peaking over the weekend.

&&

.DISCUSSION...
current radar and visible satellite imagery shows very light and
isolated returns across portions of Central Oregon under partly
cloudy skies. This is in response to an upper level low pressure
currently over Montana, that will continue to depart to the
northeast and into southern Manitoba over the next 24 hours. A
weak, transient ridge of high pressure is beginning to break up
earlier cloud cover through the Columbia Basin, but an incoming
shortwave will return clouds overnight into Tuesday. These
synoptic features have also allowed a pressure gradient to
develop along the Cascades to attribute to breezy conditions
across the Columbia Gorge, east slope of the Cascades, Lower
Columbia Basin, and the Kittitas Valley. The weak shortwave
stalls along the coast overnight tonight before slowly passing
through the area Tuesday followed by a second shortwave on
Wednesday. The first shortwave will erode the backside of the
transient high pressure ridge, which will provide enough
instability for isolated thunderstorm development across the
east and south edges of Grant, Union, and Wallowa Counties.
Enough moisture should be present in any developing storm cells
to provide wetting rain amounts (>0.10"). Wednesday`s system is
expected to be much drier as the shortwave stays further north
and passes along the Canadian border. This should only lead to
an uptick in cloud cover and afternoon winds.

Flow aloft turns from the northwest to more westerly Thursday,
then more from the southwest Friday into Saturday, which
initiates a warming and drying trend through the latter half of
the week. Below normal high temperatures will become near to
above normal values on Saturday, with highs breaking into the
low to mid-90s across portions of the Lower Columbia Basin on
Sunday. These high temperatures, coupled with overnight lows
only dipping into the mid-to upper 50s, will attribute to
isolated pockets of moderate HeatRisk across the Lower Columbia
Basin and northern Blue Mountain foothills Sunday and Monday.
However, guidance is not in full agreement regarding how
enhanced the southwest flow aloft and upper level ridge will be
over the weekend. At this time, 80% of ensemble members
advertise a similar or slightly cooler outcome. The 20% warmer
outcome is rather substantial though, suggesting Sunday`s high
temperature being 5 degrees warmer than the current forecast.
This may be an outlier as 27% of ensemble members were
suggesting this warmer outcome just 24 hours ago. Further
analysis of this trend is necessary, which may lead to more
areas of moderate HeatRisk Sunday. Stay tuned. 75

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...VFR conditions to
prevail through the period. With lack of precip moving through
the area, CIGs should generally remain above 8kft AGL at all
sites, and become mostly SKC or FEW tomorrow. Breezy winds will
continue to impact site YKM through 8Z, with winds persisting at
site DLS through the period. Winds at site ALW will remain
between 12-17kts with periodic gusts to around 20kts. Winds
will increase to 12-17kts with gusts up to 25kts at sites
PDT/RDM/BDN late tomorrow morning through the afternoon.
Lawhorn/82

&&

.FIRE WEATHER...
Minimal fire weather concerns this week as early week winds will
be accompanied by afternoon humidities between 35-45% with
excellent overnight humidity recoveries of 70-85%. There is a
slight threat for isolated thunderstorms across Grant, Union,
and Wallowa counties Tuesday, but chances are minimal as
coverage is confined to the south and east of OR 693, 694, and
695. Minimum humidities trend lower toward the end of the week
and through the weekend, but winds should stay rather light as
upper level ridging develops. 75

&&

.Preliminary Point Temps/PoPs...
PDT  52  75  44  75 /   0  10   0   0
ALW  56  77  51  77 /   0  10   0   0
PSC  56  81  49  80 /   0  10   0   0
YKM  55  82  49  81 /   0   0   0   0
HRI  54  78  47  78 /   0   0   0   0
ELN  51  73  45  74 /   0   0   0   0
RDM  40  73  34  74 /   0   0   0   0
LGD  50  74  42  76 /   0  10   0   0
GCD  47  76  39  77 /   0   0   0   0
DLS  54  72  50  73 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory until midnight PDT tonight for WAZ026.
OR...None.

&&

$$

DISCUSSION...82
AVIATION...82
FIRE WEATHER...75