846
FXUS66 KPDT 200622
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1022 PM PST Mon Jan 19 2026

Updated Aviation Discussion

.AVIATION...06Z TAFs...MVFR or lower conditions to prevail through
the period. Vsby is expected to remain VFR at sites
DlS/PDT/YKM/ALW/PSC through the period, however freezing fog with
visibilities of 1/4SM to 1 1/2SM will impact sites RDM/BDN
through the morning period. CIGs will gradually drop throughout
tonight, but remain MVFR at sites DLS/PSC, IFR or higher at sites
PDT/YKM/ALW, with IFR/LIFR CIGs at sites RDM/BDN through the
period. A system passing to the east of the region tomorrow may
help to breakdown low level temperature inversions over the TAF
sites, but confidence is low (15-20%) in inversions breaking
enough for stratus to briefly dissipate tomorrow afternoon.
Otherwise, winds will remain light through the period. Lawhorn/82


&&

.PREV DISCUSSION... /issued 307 PM PST Mon Jan 19 2026/

.DISCUSSION...Current satellite imagery shows a low stratus layer
across the Columbia Basin area extending to Central OR. While
majority of freezing fog has lifted over North-Central OR and
Foothills-Southern Blue Mountain of OR, the webcams are currently
showing ongoing freezing/dense fog along US-97 between Cow Canyon
and Shaniko.

The northwesterly flow dominates the region with the upper ridge
along the PacNW coast through work week. Thanks to the low stratus
layer and temperature inversions, this will help keep high temps in
the 30s and 40s. The boundary layer will remain dry from the ongoing
subsidence, which will assist in lowering dewpoints and temps to
near or below freezing during overnight hours. That said,
freezing/dense fog could redevelop during early morning hours and
night hours. Uncertainty still remain on the strength of the fog and
extent, but we will monitor the forecast area and make any
adjustments if need be. HREF raw ensembles show a 15-30% probability
for visibilities less than 1/2SM but 30-40% prob during morning
hours for tonight through early Tuesday morning, which might impact
driving conditions.

With the ongoing inversions, stagnant air conditions will continue
for the next few days with low low transport winds (10 mph or less)
and mixing heights around 1.5 kft or lower. Any pollutants, haze,
and/or smoke may still be trapped near surface level thus resulting
poor ventilation, keeping Air Stagnation advisories in place until
late Tuesday afternoon. Feaster/97




&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  22  33  20  35 /   0   0   0   0
ALW  25  34  23  35 /   0   0   0   0
PSC  24  37  23  37 /   0   0   0   0
YKM  22  39  21  37 /   0   0   0   0
HRI  23  35  23  35 /   0   0   0   0
ELN  21  35  20  35 /   0   0   0   0
RDM  20  43  17  42 /   0   0   0   0
LGD  24  41  21  42 /   0   0   0   0
GCD  25  48  25  48 /   0   0   0   0
DLS  26  38  25  38 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Air Stagnation Advisory until 4 PM PST Tuesday for ORZ041-044-
     507-508-510-511.

WA...Air Stagnation Advisory until 4 PM PST Tuesday for WAZ024-
     026>029-521.

&&

$$

DISCUSSION...97
AVIATION...82