903
FXUS66 KPDT 270810
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
110 AM PDT Sat Sep 27 2025

.DISCUSSION...High pressure over the forecast area will start to
shift eastward today as a wet, cooler pattern begins to materialize
for the PacNW late Sunday onward. A broad surface low based in the
Gulf of Alaska will make for prevailing SW flow aloft over the
region for most of the work week, as models generally have this
system slow to progress inland. This will make for persistent shower
chances starting late Sunday night across mainly our mountain zones,
before becoming widespread during the day Monday.

QPF ensemble guidance is coming into better agreement on the
rainfall amounts expected this week from this system, scaling back a
tad on the first half of the week`s accumulations, but increasing
amounts Thursday into Friday as it better accounts for the slow
progression of this system. Pockets of isolated thunderstorms are
possible (15-25% chance) across our high mountain zones in the Blues
and Cascades during the day Monday and Tuesday, but given the time
of year, expectation is that rain will generally be shower-y in
nature rather than convective. Will this week prove to be season-
ending for wildfires? It doesn`t look to be quite the soaker we`re
hoping for, but with active incidents concentrated across the
Cascades, confidence is high (>80%) that wetting rains will fall
where it is currently needed the most, with lower chances (20-30%)
of wetting rains occurring across the lower Columbia Basin by the
end of the week.

Ensemble guidance generally suggests that the core of this low will
pass through the PacNW by the end of the work week, with most
members depicting a benign zonal pattern for next weekend.
Temperatures will generally waver around seasonal averages under
this drier pattern. Evans/74

&&

.AVIATION...12z TAFs...VFR conditions expected. Expect mostly clear
skies outside of a few high clouds and light, terrain-driven winds
less than 10 kts. Sct high clouds will start to build in the evening
ahead of the next weather system expected to arrive late Sunday.
Evans/74

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  81  52  82  54 /   0   0   0  10
ALW  81  57  82  59 /   0   0   0  10
PSC  80  49  82  54 /   0   0   0  10
YKM  79  49  82  55 /   0   0   0  20
HRI  81  51  82  56 /   0   0   0  10
ELN  78  46  80  51 /   0   0   0  20
RDM  84  43  84  48 /   0   0   0  20
LGD  83  47  85  52 /   0   0   0  10
GCD  83  49  85  52 /   0   0   0  10
DLS  83  55  84  59 /   0   0   0  20

&&

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

$$

SHORT TERM...74
LONG TERM....74
AVIATION...74