479
FXUS66 KPDT 220429
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
929 PM PDT Sun Jun 21 2026

.KEY MESSAGES...
1. Dry and warm conditions will persist through Thursday
    *Heat Advisory Issued*

2. Elevated Fire Weather concerns return Wednesday and Thursday

3. Pattern shift Thursday will bring cooler temperatures and
   mountain rain

&&

.DISCUSSION...
Current satellite show mostly clear skies across the region today.
Northwest flow has ushered in some slightly cooler air for today
allowing for temperatures to be a bit cooler than past days. NBM has
temperatures in the mid to upper 80s across much of the region with
a few isolated locations in the Basin hitting 90 degrees with 70-90%
NBM raw ensembles probabilities for the Basin, foothills and Gorge
and 60-80% for central and north central OR.

After today, models show the axis of the ridge to begin to move over
the region bringing back the increased temperatures. NBM shows
temperatures Monday to be 5 degrees warmer than Sunday with
temperatures returning to the 90s in the Basin and upper 80s along
the foothills and central OR with 80-90% probabilities. OVernight
lows into Tuesday will also be elevated with areas in the gorge
seeing lows in the upper 50s to low 60s with raw ensembles showing
agreement of 80-90%. With no real overnight relief from the heat an
Heat Advisory has been issued for the Gorge as daytime temperatures
coupled with no recoveries overnight has the area reaching a major
HeatRisk of 3 of 4. The Basin, foothills of the Blues and central OR
are all HeatRisk of 2 of 4 while the remaining areas are 1 of 4.
HeatRisk of 2 of 4 will remain for the aforementioned areas through
Wednesday.

With the continued dry and warm conditions over the past few weeks,
the RHs have remained critical with little to very little overnight
recoveries. With that said, the incoming system Wednesday and
Thursday will cause elevated fire weather concerns due to critical
RHs and winds. As of now the NBM shows RHs across some isolated
pockets of RFW criteria Wednesday with RHs in the low to mid teens
and sustained winds of 10-20 mph. Thursday however, NBM in-house
calculations show there to be widespread RFW criteria overlap
through the Kittitas/Yakima Valleys, the Columbia River Basin of OR
and WA with some isolated pockets in north central OR as well. With
RHs at 15% and winds at 20 mph, calculations using the two points of
information, NBM WSUP Viewer is already showing 30-50% probabilities
of areas reaching this criteria with some packets already showing
60-70%. Will continue to monitor as the day comes closer.

Thursday morning, models show an upper level system moving into the
region from the northwest. Clusters show some variance between the
models with mostly amplitude and timing. Regardless, models show the
system to bring with it mountain rain and cooler temperatures. Rain
amounts will be low with only 25-30% of the NBM raw ensembles
showing 0.01 inches of rain Thursday before becoming widespread and
only 15-20% of the raw ensembles showing 0.01 inches across the
region Friday. Thursday NBM raw ensembles show 80-90% probabilities
of temperatures above 80 degrees decreasing to 60-80% probabilities
of temperatures above 70 degrees Friday.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Expect VFR condtions to continue under clear sky for this set
of TAFs. West to northwest winds remain under 10 knots



&&

.FIRE WEATHER...
Continued dry and warm conditions will affect the
region. Wednesday winds will begin to increase just enough for some
pockets of critical fire weather. Thursday is the primary day of
concerns as winds are expected to be sustained winds of 15-25 with
RHs in the low to mid teens. In-house calculations show 30-50%
probabilities over the vast majority of zones WA690
Kittitas/Yakima Valleys), WA691 and OR691 (Columbia Basin of WA
& OR) meeting criteria. Will continue to monitor as the day
come closer but can say with 50-70% confidence Wednesday and
Thursday will be elevated fire days.

&&

.Preliminary Point Temps/PoPs...
PDT  52  88  53  90 /   0   0   0   0
ALW  58  89  58  92 /   0   0   0   0
PSC  57  92  56  94 /   0   0   0   0
YKM  57  90  60  92 /   0   0   0   0
HRI  55  91  56  93 /   0   0   0   0
ELN  54  87  57  89 /   0   0   0   0
RDM  46  88  51  89 /   0   0   0   0
LGD  48  85  50  89 /   0   0   0   0
GCD  46  89  49  93 /   0   0   0   0
DLS  59  93  63  95 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Heat Advisory from 11 AM Monday to 11 PM PDT Tuesday for
     WAZ024.
OR...Heat Advisory from 11 AM Monday to 11 PM PDT Tuesday for
     ORZ041.

&&

$$

DISCUSSION...90
AVIATION...71
FIRE WEATHER...90