397
FXUS66 KPDT 030610
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1110 PM PDT Tue Sep 2 2025

.EVENING UPDATE...Expanded and extended Heat Advisories through 8
PM PDT Thursday for multiple forecast zones in south-central to
southeast Washington and eastern Oregon. While overnight
temperatures will likely (>70% confidence) stay unseasonably
mild/warm in central Oregon due to cloud cover, opted to expire
the Heat Advisory that was in effect due to insufficient
confidence that Wednesday afternoon high temperatures will reach
advisory thresholds relative to more cloud-free areas to the north
and east where expansions/extensions were made. Plunkett/86

&&

.AVIATION...06Z TAFs...VFR conditions are forecast for all sites
through the valid period. While sub-VFR conditions may occur
Wednesday afternoon and evening at BDN/RDM in showers and/or
thunderstorms, confidence is low (<30%).

Mid- and high-level clouds are expected to increase in coverage
from south to north overnight through Wednesday as a compact
weather system moves north from California. Aside from VCSH at
BDN/RDM, no precipitation has been included. Confidence was just
too low (20%) to include PROB30 groups at BDN/RDM from 22Z
Wednesday until 04Z Thursday for -TSRA.

Winds will be mostly diurnally and terrain-driven at 12 kts or
less outside of any outflow winds from thunderstorms. Outflow
wind gusts in excess of 40 mph will be possible, but unlikely
(<20% chance), at BDN/RDM. Plunkett/86

&&

AVIATION...00Z TAFs...VFR conditions prevail through the TAF
period with generally light winds. However, sustained winds of 12-
20kts may develop over KRDM/KBDN with gusts up to 30-40kts this
evening (<20% confidence). Feaster/97

.PREV DISCUSSION... /issued 217 PM PDT Tue Sep 2 2025/

DISCUSSION...Satellite shows some haze/smoke making its way into
the Pendleton area. We`ll see this persist through at least the
next day. Light and variable winds will lead to less transport of
the smoke. Smoke caused by the Wildcat fires is mostly responsible
for the Air Quality Alert out for Kittitas and Yakima County.

Going through the week, an upper level ridge over the PacNW will
continue to build into the area, bringing spotty triple digit
temperatures across the Basin. Temperatures will gradually warm up
another 5-10 degrees through Thursday, until the ridge pushes off
to the west. Extreme Heat Warnings and Heat Advisories are issued
across most of the region. Central OR will cool down quicker below
Major level thanks to incoming clouds and showers from an upper
level low over California. This upper feature will bring
showers/thunderstorms to the Central OR region through overnight
tonight and every day through the middle of the week. Chances are
slight (15-25% chance) of storms developing over Central OR.
Storms are likely to be dry going through tonight, but will
progressively become wetter as the week goes on. Expecting
coverage of shower activity to expand through the Southern Blue
Mountains and parts of the Foothills by late this week, giving us
relief from the heat we will experience over the next couple of
days.

With the caveat of dry thunderstorms, a Red Flag Warning was
issued for parts of Central OR through tomorrow. Unsure about
Wednesday and beyond as confidence drops (>15%) on whether or not
lightning will verify an event. CAMs suggest >40 dbz paintballs
going through tomorrow on the southern part of Deschutes County.
Coupled with low PWAT values of 0.7-0.9", a warning was issued.
Through the end of the week going into next week, guidance suggest
temperatures cooling to the high 70s to low 80s, although at the
expense of widespread precip coverage, thanks to a trough moving
ashore from the Gulf of Alaska into the PacNW. Although need to
keep an eye on thunderstorm coverage going into the weekend, not
anticipating anything to suggest we will see dry storm events.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  65  98  66  97 /   0   0   0   0
ALW  70 100  72  99 /   0   0   0   0
PSC  62 101  64 100 /   0   0   0   0
YKM  66 102  68 100 /   0   0   0   0
HRI  62 100  65 100 /   0   0   0   0
ELN  61 100  65  98 /   0   0   0   0
RDM  58  91  54  95 /  20  10  20  10
LGD  62  99  63  96 /   0   0  10   0
GCD  61  95  63  95 /  10  10  10   0
DLS  68 100  68 101 /   0   0  10   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Extreme Heat Warning until 8 PM PDT Thursday for ORZ041-044-507-
     508-510.

     Heat Advisory until 8 PM PDT Thursday for ORZ049-050-502-505.

     Red Flag Warning until 8 PM PDT Wednesday for ORZ705.

WA...Extreme Heat Warning until 8 PM PDT Thursday for WAZ024-026>029-
     521.

     Heat Advisory until 8 PM PDT Thursday for WAZ030-523.

&&

$$

EVENING UPDATE...86
SHORT TERM...95
LONG TERM....95
AVIATION...86