Hermiston, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

346
FXUS66 KPDT 242335
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
435 PM PDT Sun May 24 2026

.Updated Aviation Discussion.


.KEY MESSAGES...
1. Dry and warm conditions today ahead of a cold front

2. Breezy to windy through the gaps Monday
    *Wind Advisory in effect*

3. Increased chances of showers Monday onward

4. Increase chances of thunderstorms Monday afternoon and again
   Thursday afternoon

&&

.DISCUSSION...
Current satellite shows mostly clear skies with some high cloud
lingering over the region. Temperatures today will remain warm with
80-90% probabilities of low to mid 80s across the Gorge, Basin,
adjacent valleys, central OR and the foothills. Elsewhere will be in
the mid to upper 70s.

Satellite shows the upper level low has formed off the coast of
Canada and steadily moving to the south. Models show ahead of the
low, a cold front will pass the area by Monday afternoon. This will
bringing increased chances of breezy to windy conditions . A Wind
Advisory has been issued for central and north central OR, the
Simcoe Highlands of Klickitat County and the Yakima Valley fro
sustained winds of 20-30 mph with gusts to 55 mph possible. 70-90%
of the NBM ensembles are in agreement. This advisory begins at !!
AM Monday through 11 PM Monday. Winds elsewhere will be breezy with
sustained winds of 10-15 with gusts to 35 possible, especially along
the foothills of southern and northern Blues and through the Kittitas
Valley.

The cold front an associated low will also bring with it increased
chances of precipitation beginning in the mountains Monday afternoon
before becoming widespread in the evening. There is a 30-50%
probability of seeing between 0.01-0.03 along the crests of the
Cascades and 0.03-0.06 over the Blues through the evening hours
Monday. As we move into Tuesday, the area where most precipitation
is expected to fall will be along the OR Cascades with up to 0.06-
0.09 inches with 60-80% of the NBM raw ensembles in agreement. The
Northern Blues also will see higher amounts of precipitation between
0.05-0.10 inches of rain with also 60-80% probabilities. As we move
into Wednesday, models become a bit more spread in their agreement,
however, 0.02-0.06 inches of rainfall accumulations are still
expected for Wednesday across the Blues. Thursday is expected to be
the most active day in the period with highest rainfall amounts over
the vast majority of the region. Much of the rainfall is expected
through central OR and along the eastern mountains and through
Wallowa Valley although models are still a bit spread on rainfall
amounts with only 30-50% chances of 0.05-0.09 inches of rain.

Lastly, models show that ahead of the incoming cold front,
instability over the area is increasing. Monday afternoon, CAMs
forecast soundings show 100-300 J/kg of CAPE intruding into the area
over the Cascades. This coupled with orographic lifting could lead
to some isolated thunderstorms over the eastern mountains and the
Blues after 5 PM Monday night with 15-20% probabilities. Models than
show the upper level low dive to the south through Wednesday before
traversing back up towards the region causing some wrap around.
Models are also showing an increase in instability due to the wrap
around of the low with forecast soundings showing CAPE values of 250-
450 J/kg, lapse rates of 7.2 C/km and lifted indices of -4. This
coupled with the orographic lift along the mountains could allow for
isolated thunderstorms across central OR and the slopes of the
Cascades Thursday with 15-20% probabilities.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
VFR conditions currently at all sites, which will stay the
course through the period. A few clouds at 25kft this evening,
but more SCT-BKN ceilings of 25kft are expected through the
morning hours associated with a more substantial cold front
approaching the area. This system will also lead to widespread
breezy conditions as gusts of 20-30kts are expected across most
terminals by noon, impacting KRDM/KBDN by mid-morning. 75

&&

.FIRE WEATHER...
Highest day of concern is Monday when RHs are in the
low to mid 20s and winds are sustained at 20-30 mph with gusts to 55
mph. This puts the Basin, isolated locations in central OR around
Prineville and Kittitas Valley in elevated fire danger for tomorrow
with 5-19% probabilities.

&&

.Preliminary Point Temps/PoPs...
PDT  51  82  43  63 /   0   0  70  20
ALW  56  84  48  63 /   0   0  60  20
PSC  54  86  45  69 /   0   0  60   0
YKM  52  78  44  69 /   0   0  30   0
HRI  53  83  44  67 /   0   0  60  10
ELN  47  73  40  62 /   0   0  30  10
RDM  45  81  34  59 /   0   0  30  30
LGD  47  86  42  57 /   0  10  70  70
GCD  46  87  39  57 /   0   0  90  70
DLS  54  77  46  69 /   0   0  30  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory from 11 AM to 11 PM PDT Monday for WAZ027-521.
OR...Wind Advisory from 11 AM to 11 PM PDT Monday for ORZ510-511.

&&

$$

DISCUSSION...90
AVIATION...75
FIRE WEATHER...90