027
FXUS66 KPDT 020528
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
928 PM PST Sun Nov 1 2026

.Updated Aviation Discussion.


.KEY MESSAGES...
- Areas of dense fog and freezing fog today.

- Near- to below-normal temperatures into next week.

- Low chance (30% or less, except for freeze-prone areas) of a
  season-ending freeze for the eastern Columbia River Gorge
  Monday.

&&

.DISCUSSION...
GOES satellite shows water vapor imagery showed a baroclinic
leaf moving into The Mountain West as deep layer drier air
associated with the upper trough moving over the Pacific and
Inland Northwest was squarely centered over the PDT forecast
area. This synoptic scale feature will be replaced by an upper
ridge by sunrise Monday morning. The light winds and clearing
skies may bring redeveloping fog in some of the fog prone
valleys as well as bring an outside fort of freezing
temperatures for the Columbia River Gorge by early Monday
morning. The NBM less than 1 sm visibility probabilities are at
33 percent across the Kittitas Valley and 20 percents across the
Northern Blue Mountains of Oregon Tonight into Monday morning
additionally the HRRR does not develop low visibility in any of
these zones while diminishing low visibility through the
evening from mountains stratus layers through late Tonight.

With clearing sky, Monday morning should be noticeably colder
than last night with the widespread cloudiness keeping the
boundary layer warmer, and more notable in the eastern zones
/Blue Mountain Valley floors like the Grande Ronde which may be
up to 10 degrees colder and in the 20s. Based on NBM QMD , the
minimum temperatures are of medium to high (50-70) confidence in
a mid to upper 20s (25 to 28F window for overnight lows at
LaGrande. The last forecast zones to yet have a true growing
season ending freeze is in the the Eastern Columbia River Gorge,
where the same 25 to 75 percentile QMD ranges from 35 to 37F
for an overnight lows. Possibly some frost but not high enough
confidence for a freeze (less than 25 percent).

Winds remain light through Monday night when winds become
breezy over the southern and eastern Mountains and the Grande
Ronde Valley into the overnight and though Tuesday. No
appreciable warm up is expected as temperatures remain near to cooler
than normal in the the 40s in the mountains and the 50s over
the lower elevations. Dry through Wednesday with increasing
chances for mountain rains Wednesday Night through Friday (20
to 60 percent confidence). A 20 percent chance for measurable
precipitation exists across the Columbia Basin on Wednesday
Night.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
VFR conditions currently at all sites, which will stay the
course for most terminals. However, KPSC is expected to
experience patchy fog that will likely drop visibilities to
around 2SM and IFR overnight into the early morning hours on
Monday - similar to last night. Current observations are
already registering 9SM with 96% RH. Winds will stay light and
below 10kts at all terminals as increasing cloud cover is
expected toward the end of the period as a result of an
incoming system. 75

&&

.Preliminary Point Temps/PoPs...
PDT  33  58  36  51 /   0   0   0  10
ALW  37  57  39  52 /   0   0   0  10
PSC  33  58  38  54 /   0   0   0   0
YKM  33  55  39  57 /   0   0   0  10
HRI  33  58  38  53 /   0   0   0  10
ELN  29  53  34  51 /   0   0  10  10
RDM  26  59  31  51 /   0   0   0   0
LGD  31  53  37  57 /   0   0   0   0
GCD  30  57  36  57 /   0   0   0  10
DLS  35  59  41  57 /   0   0  10  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...None.
OR...None.

&&

$$

DISCUSSION...71
AVIATION...75