320
FXUS66 KPDT 132241
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
Issued by National Weather Service Boise ID
341 PM PDT Fri Sep 13 2024

.SHORT TERM...Tonight through Sunday night...A trough over the
Gulf of Alaska will move south along the British Columbia coast
and across the WA/OR coast through Sunday. As the trough
approaches, the flow aloft shifts to the west and then southwest.
Breezy westerly winds expected tonight along the Cascade gaps this
evening into Saturday afternoon. Isolated showers form across the
WA zones on Saturday morning as clouds increase from the
northwest. Much of the energy from the upper level trough moves
south along the Pacific NW coast, moving into northern CA by
Sunday night. Little sensible weather impacts expected on Sunday
for the Columbia Basin, but as the trough moves south along the
coast, a deformation zone sets up over the Blue Mountains on
Sunday morning, bringing light rain showers, with precipitation
amounts generally under 0.10 inch. The NBM 12-hr probability of
precipitation greater than 0.1 inches ending Sunday night will be
30-50% across the Blues, Ochoco-John Day highlands, and Wallowa
County. Surface winds shift to the north Sunday afternoon, with
temperatures cooling around 5 degrees from Saturday.

.LONG TERM...Monday through Friday...Showers will continue over the
eastern mountains on Monday as a closed low tracks through northern
CA before lifting northeastward through Idaho. There was little
change in the forecast low track with the 12Z operational models,
which would place the best chance for precipitation over NE Oregon
and SE WA Monday night into Tuesday. With the current low track, the
heavier precipitation is still forecast to remain further east over
Idaho. A secondary low will drop south along the coast Tuesday,
taking a similar coastal track to the first system. This will focus
precipitation along the Cascade crest Tuesday into Wednesday.
Increased northerly flow aloft and a surface low to the east will
act to ramp up west-northwest winds over the region Tuesday night
into early Wednesday. Forecast models dig this second low further
south into the Great Basin before turning it eastward on Thursday.
This track favors drier conditions over all zones after Wednesday.
While there is some uncertainty on low tracks and accompanying
precipitation, there is high confidence that temperatures will be
cooler through the work week with Tuesday and Wednesday the coolest
days.

&&

.AVIATION...Generally VFR. Increasing mid and high clouds.
Isolated showers near KYKM KPSC early Sat morning. Surface winds
SW-NW 5-15kt, strongest near KDLS KPSC, increasing to W-NW
10-20kt Sat afternoon.


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  51  74  47  66 /   0   0  10  20
ALW  54  77  51  69 /  10  10  10  20
PSC  58  79  53  72 /  10  10   0  10
YKM  51  76  43  72 /  10  10   0   0
HRI  56  78  51  71 /  10   0   0  10
ELN  52  74  46  72 /  20  20  10   0
RDM  45  73  42  64 /   0   0  10  30
LGD  48  74  46  66 /   0  10  20  40
GCD  47  77  46  66 /   0   0  10  40
DLS  56  75  52  72 /   0  10  10  10

&&

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

&&

$$

SHORT TERM...KA/BOI
LONG TERM....DG/BOI
AVIATION...KA/BOI