053
FXUS66 KPDT 122340
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
440 PM PDT Sat Sep 12 2026

.KEY MESSAGES...
- Widespread rain is likely overnight into Sunday.Areas in the
flood watch should have many way to get alerts.

- Wind gusts above 30MPH are likely much of Sunday morning.

&&

.DISCUSSION...
A low pressure system currently located off the coast of Oregon
and Washington is moving south eastward, it should move ashore
during the afternoon. After moving inland the low should begin
steering towards the northeast. Rain should begin to develop as
it moves inland. Overnight the rain will become more
widespread.


Ensemble and deterministic gudience still remains in
disagreement on QPF totals. Holistically the CWA should see an
above normal amount of rain this time of year with EFI values
between .8 and .9 and SOT of 2 and 1 on the Oregon/Washington
border, putting emphasis on a potential for a high QPF rain
event. Overall the QPF has decreased over the last several runs
and reseeded more north toward our neighboring CWAs. NBM 10th
percentile has the Kittitas valley receiving 1" of rain and the
Colombia Basin and the Blue Mountains mostly receiving .20".
The southern leeward side of the Cascades will likely be rain
shadowed out of higher QPF totals. The 90th percentile QPF again
Has the Kittitas Valley in higher QPF values and the Columbia
Basin exceeding 1.20". Probabilities of >= .50" occurring
excluding those along southern leeward side of the Cascades
which will again be rain shadowed. >= 1" is where the Probs really
decline throughout most of the area, aside from the Kittitas
and Yakima Valley which remain >=80% chance.

Thunderstorms remain at <= 20% chance mostly occurring in the
higher elevations of the Blue Mountains overnight. A potential
exists for flooding over the Paradise and Hagen fires subsequent
flood watches have been issued for those areas.

Wind gusts probs through much of Columbia Gorge, Basin,
Kittitas Valley and Foothills of the Blue Mountains have a >90%
chance of 35mph or greater. Most of the CWA should see at least
20-30 with those areas mentioned seeing higher gusts.

Temperatures over the weekend remain well below seasonal
averages. Sundays high temperatures will remain in the 60-65F
with cooler temperatures in the higher elevations. After sunday
and through out the week temperatures will rebound to climate
norms.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
The main concerns through the TAF period will be elevated
winds, lower CIGs, and showers. Currently, VFR conditions are
present at the TAF sites, but lower CIGs to MVFR are forecast at
several terminals by around 10-12Z or so. CIGs will then
fluctuate somewhat between MVFR and VFR through the day on
Sunday (especially during periods of heavier showers). As for
winds, expect sustained west southwest winds between 10-20 knots
and gusts to between 20-35 tonight through Sunday afternoon.
Shower chances also increase this evening, with medium to high
chances persisting at times through Sunday afternoon before
tapering off Sunday evening.

&&

.Preliminary Point Temps/PoPs...
PDT  46  63  44  70 / 100  70  40   0
ALW  51  63  50  71 / 100  80  70   0
PSC  48  64  46  73 /  90  80  30   0
YKM  50  62  45  68 / 100 100  10   0
HRI  47  65  46  73 / 100  60  30   0
ELN  44  57  41  66 / 100 100  20   0
RDM  36  61  33  71 /  90  10   0   0
LGD  45  62  43  70 /  90  60  60   0
GCD  44  61  40  70 /  90  40  10   0
DLS  52  66  51  74 / 100  60  10   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Flash Flood Watch through Sunday evening for WAZ030.
OR...Flash Flood Watch through Sunday evening for ORZ502.

&&

$$

DISCUSSION...18
AVIATION...99/CGAA