946
FXUS66 KPDT 170926
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
226 AM PDT Fri May 17 2024

.SHORT TERM...
Today through Sunday night...
Latest radar showed some light showers associated with upper
trough and strong shortwave making its way across the region.
This trough and shortwave should continue moving eastward through
the overnight hours and the main shortwave should be in Idaho by
daybreak. Precipitation will linger over the mountains through the
morning before ending. Today`s precipitation will mainly be 0.10
inches or less, except along the crest of the Washington Cascades,
which could receive up to 0.20 inches.

Friday afternoon into Friday night looks completely dry, then
another trough and strong shortwave will drop southeastward from
British Columbia and move across the Pacific northwest Saturday
into Sunday, with a second shortwave moving sown Sunday night,
which will further deepen the trough as it moves eastward.

Any precipitation that occurs, which will mainly be Saturday
afternoon into Saturday night, then again Sunday afternoon will
mainly be light and in the mountains, and be 0.10 or less.

Winds will continue to be gusty across the Kittitas Valley, Simcoe
Highlands, Columbia Gorge and Oregon Columbia Basin and Oregon
Blue Mountain Foothills. Winds will decrease through the day into
tonight. Winds will increase again Saturday afternoon into
Saturday evening and gust in the 25 to 35 mph range with gusts as
high as 40 mph possible in these same general areas, before
decreasing again on Sunday. Winds will increase again on Sunday
afternoon, but should be a bit lower only into the 20s, possibly
as high as 30 mph and not as widespread.

The wind advisory for the Kittitas Valley will remain in effect,
otherwise it does look like that many areas will be close but just
short and areal coverage of winds will be less today and decreasing
during the day. The NBM probabilities of wind gusts >= 39 mph are
generally 80 to 100% across most of the areas mentioned above.
However, the NBM probabilities of winds gusts >= 47 mph are 60 to
80% over a smaller area than on Thursday. So, again, will need to
keep an eye on this, especially through the morning, but will not
issue any new advisories at this time.

On Saturday, the NBM probabilities of wind gusts >=39 mph are high
one again, 80 to 100%, but the probabilities of wind gusts >= 47
mph are much lower generally around 40 to 60%, with the exception
of the Kittitas Valley which is still around 80 to 90%.

On Sunday, the NBM probabilities of wind gusts >= 39 mph are again
80 to 100%, but the probabilities of wind gusts >= 47 mph are
even lower, and in a smaller area. Probabilities are Generally 30
to 50%, except for the Kittitas Valley.

With the passage of the trough, temperatures today and for the
next few days will be about 10 degrees cooler than on Thursday
and much closer to normal. Highs will be in the upper 60s to lower
70s over the area, today and Saturday then low to mid 60s to
around 70 degrees on Sunday.


.LONG TERM...
Monday through Friday...Not much change in messaging for the
forecast next week, as the PacNW looks to be enveloped by a trough
pattern of some kind for most of the period. Ensembles continue
to converge on a solution, making for relatively high confidence
(70%) on the forecast.

The low currently impacting our area will begin to shift eastward on
Monday, leaving the trough axis over the far eastern half of the
forecast area with dry NNW flow aloft behind. The front associated
with this trough axis may trigger some isolated showers and
thunderstorms over the far eastern mountains, namely in Wallowa
County, but the airmass throughout the weekend into Monday is dry,
so PoPs are on the lower end (20-30%).

Tuesday into Wednesday, more widespread threats for shower activity
develop as a low from the Gulf of Alaska dives down into our area.
Ensembles are in pretty good agreement on depicting this low, which
would generate enough instability across the forecast area to
generate showers through the midweek. Guidance is overall light on
QPF this far out, as to be expected, but given the more NW origin of
this system, combined with the drier center looking to fall just
over central Washington, not expecting particularly impactful
amounts of precip, but the setup is certainly there for on/off
shower activity starting Tuesday and lasting into even early
Thursday. Breezy winds will result from the arrival of this low, and
some thunderstorms could pop up as well, primarily over the eastern
mountains, however considering the cooler air this system is
bringing in, not anticipating thunderstorm activity to be
particularly strong at this time.

Ensembles continue to depict us under a trough pattern heading into
the end of next work week. NBM paints slight chance to chance PoPs
across the forecast area as a result. Expect temps to remain around
or even slightly below seasonal averages, as colder, Canadian air is
ushered in via this trough pattern. Evans/74


&&

.AVIATION...
12z TAFs...VFR conditions expected, with gusty winds continuing
across all sites through the period. Expect west winds gusting up
to 30 kts at times, with winds expected to wind down by nightfall
Friday night. Some light low to mid-level cloud cover early this
morning will give way to clear skies during the day, before mid-
level clouds start to build in again this evening. Evans/74



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  64  39  67  39 /   0   0   0  10
ALW  67  44  69  44 /   0   0   0  10
PSC  72  45  73  45 /   0   0   0  10
YKM  69  38  69  38 /   0   0   0   0
HRI  69  43  72  43 /   0   0   0   0
ELN  63  41  63  40 /   0   0   0   0
RDM  65  34  67  33 /   0   0   0   0
LGD  60  36  67  38 /   0   0   0  10
GCD  63  36  69  36 /   0   0   0   0
DLS  67  44  67  45 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...Wind Advisory until 2 PM PDT this afternoon for WAZ026.

&&

$$

SHORT TERM...77
LONG TERM....74
AVIATION...74