660
FXUS66 KPDT 010233
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
733 PM PDT Sun Aug 31 2025

.UPDATE...Updated the grids as the new model runs show having
slightly higher chances (20-25%) of showers and a few isolated
thunderstorms through the Basin and Kittitas Valley through 11 PM.
Current radar already shows a few cells popping up over the PDT
radar as well as east of Connell. There have been continued cells
moving through Grant and Crook counties, but ground observations
show no rainfall has been associated with them. Chances of showers
with a possible of a thunderstorm or two will remain through the
overnight hours with probabilities remaining in the low to mid
20% for the Basin and Kittitas Valley. Lastly, haze will continue
to linger over the vast majority of the region through the night
and into tomorrow. Bennese/90

.AVIATION UPDATE...06Z TAFs...VFR conditions will persist through
the forecast period with the only exception being RDM/BDN as
southwest flow is bringing in smoke and haze from the Emigrant
Fire to the southwest of the area. Otherwise, CIGs will be
primarily SCT and 15kft. Winds will be diurnally driven and
remain below 10kts. Bennese/90

&&

.PREV DISCUSSION... /issued 430 PM PDT Sun Aug 31 2025/

UPDATED AVIATION.

AVIATION...00Z TAFs...VFR conditions prevail through the period.
Not expecting any significant VIS and CIG issues, so not putting
any MVFR for the next 24 hours. Winds are generally light and
variable with the exception of the DLS reaching around 20-30 knot
gusts, but should calm down to 5-10 knots by the early morning
hours.

PREV DISCUSSION... /issued 122 PM PDT Sun Aug 31 2025/

DISCUSSION...Water vapor imagery this afternoon shows the first
signs of the offshore low retrograding back toward the north
Pacific. The motion of this low is slow, however, and while it
remains in the vicinity of the PacNW, moisture will continue to pump
inland. The mid-level winds will shift more southerly today,
allowing for drier air to move into the forecast area, however there
looks to be just enough of a southwesterly orientation across the
Washington half of the forecast area to support at least a low end
(15%) chance of isolated showers and storms this evening. CAMs
suggest the bulk of the threat will fall north of the forecast area,
but did make mention of a 15% chance over primarily Kittitas County,
where the latest CAMs suggest at least a hint of a cell developing.

Labor Day onward, focus shifts toward that of heat, along with an
isolated thunderstorm threat in central Oregon. As the
aforementioned low continues to retrograde, an upper-level wave
looks to circulate in Tuesday evening into early Wednesday morning,
offering another chance of showers and storms across much of
southern Oregon. Models don`t have a great grasp of this system as
of yet, and CAMs don`t quite go out far enough to assist in forecast
confidence, but will at least broadly mention the threat of storms
for central Oregon. Our neighboring offices have issued Fire Weather
Watches along the southern and central Oregon Cascades, but models
as of now suggest better instability and mid-level moisture west of
the Cascades, so will hold steady for now, but would not be
surprised if we change course soon, especially as newer runs of the
CAMs come in.

Once the low fully retrogrades, the PacNW will find itself between
two troughs for the latter half of the work week. The high pressure
wedged between will allow temperatures to climb toward the century
mark around Wednesday in the lower Basin, with highs well into the
90s across the adjacent valleys. While these temps don`t initially
sound oppressive at first, keep in mind we`ll be in September by
then, so several daily temperature records will be at risk of being
broken Tuesday through Thursday. Evans/74

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  61  93  62  97 /  10   0   0   0
ALW  67  95  68  98 /  10   0   0   0
PSC  61  95  61  98 /  10   0   0   0
YKM  62  93  63  98 /  20   0   0   0
HRI  62  95  62  98 /  10   0   0   0
ELN  59  93  59  97 /  20  10   0   0
RDM  50  92  50  96 /   0   0   0   0
LGD  59  96  61  98 /   0   0   0   0
GCD  58  95  59  98 /  20   0   0   0
DLS  63  92  63 100 /  10   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Extreme Heat Watch from Tuesday morning through Thursday evening
     for ORZ041-044-507-508-510.

WA...Extreme Heat Watch from Tuesday morning through Thursday evening
     for WAZ024-026>029-521.

&&

$$
UPDATE...90
SHORT TERM...74
LONG TERM....74
AVIATION...90