149
FXUS66 KPDT 262156
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
256 PM PDT Sun Apr 26 2026

.Updated Aviation Discussion.


.KEY MESSAGES...

- Slight chance of showers each day through Tuesday, mainly
  over the mountains

- Gradually warming to near or above normal through this week

&&

.DISCUSSION...
Water vapor imagery shows a deep closed low downstream over the
Canadian Prairies. Meanwhile, a couple weak shortwaves embedded
within northerly flow aloft on the west side of the
aforementioned low are sliding south over the Pacific
Northwest. Predominantly clear to partly skies are present
across the lower elevations, while the mountains have seen
scattered to numerous cumulus develop. A few isolated showers
are evident within the cumulus field, mainly over Wallowa
County. Anticipating convection will remain shallow today given
the lack of vertical extent of CAPE profiles in forecast
soundings (EL around 12-18 kft) from HREF and REFS NWP
guidance.

Looking ahead, flow aloft will turn more northwesterly by
Monday and Tuesday, with a couple shortwaves and weak diurnally
driven instability (CAPE of 500 J/kg or less per latest CAMs)
providing impetus for another round of isolated to scattered
showers, mainly over the mountains.

Wednesday through the remainder of the week, ensemble cluster
analysis shows 500-hPa heights rising to near or above normal
over the Pacific Northwest and vicinity. Roughly 80-90 percent
of members place dry conditions region-wide, though all
ensemble clusters now show hints of a trough or closed low
moving over southern Canada or the Northern Tier sometime
between late Thursday and late Friday. Confidence in the feature
providing significant precipitation to the forecast area is low
(10-20 percent).

By next weekend, uncertainty in the 500-hPa height field
burgeons as ensemble guidance struggles to resolve the
evolution of an upper-level closed low and upper-level ridge in
the vicinity of the Pacific Northwest. Based on the 00Z
ensemble runs, roughly 55 percent of members keep the region
warm and dry under a ridge, while the remaining members place
the low in a position that would provide precipitation and
cooler temperatures. 86

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
VFR conditions currently across all sites, which will stay the
course through the period. The only exception will be KBDN,
which is expected to drop to MVFR conditions during the early
morning hours due to nearby prescribed fire smoke reducing
visibilities to around 3SM and ceilings of 7kft. Breezy winds are
also expected for KRDM/KBDN until sunset with gusts of 15-20kts. 20-
25kt gusts will also be possible for KDLS by late Monday morning.
Elsewhere, winds will stay light and below 10kts. 75

&&

.Preliminary Point Temps/PoPs...
PDT  62  38  64  42 /   0  10  20   0
ALW  62  41  65  45 /  10  10  20   0
PSC  67  40  71  43 /   0   0   0   0
YKM  67  38  70  42 /  10  10  10   0
HRI  66  39  69  44 /   0  10   0   0
ELN  63  35  63  40 /  10  10  10   0
RDM  60  29  61  30 /  10  10   0   0
LGD  57  33  58  35 /   0  10  50  10
GCD  57  31  58  34 /   0   0  30   0
DLS  69  42  67  45 /  10  10  10   0

&&

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

&&

$$

DISCUSSION...86
AVIATION...75