011
FXUS66 KPDT 061003
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
302 AM PDT Mon May 6 2024

.SHORT TERM...Today through Wednesday...The upper level low that
brought the abundant precipitation to the forecast area has moved
into the northern Rockies. The last of the precipitation associated
with it is over Wallowa County and will exit into Idaho by sunrise.
This leaves the region under a west to northwest flow with another
shortwave trough coming onto the coast at this time. This will
spread moisture and increase instability across the forecast area
this morning leading to increasing shower activity by mid to late
morning. Showers will peak in the afternoon and persist into the
evening before a decrease overnight. There will also be a 15-25%
chance of thunderstorms mainly over the eastern portion of the
forecast area into the evening. Existing Winter Weather Advisories
will continue for the crest of the Oregon Cascades and higher
elevations of the northern Blue Mountains.

As mentioned, shower activity will decrease overnight but not end as
showers are expected to linger over the mountains which persist
through Tuesday. Showers will come to an end Tuesday night as a
ridge of high pressure over the eastern Pacific begins building into
the region.

Breezy to windy conditions are expected again today and persist
through Tuesday with some minor decrease in winds overnight.

.LONG TERM...Thursday through Monday...The long term remains
mostly quiet in regards to sensible weather concerns as high
pressure ridging brings in notably above normal temperatures, but
keeps our region quiet otherwise with clear skies.

The overall synoptic pattern remains fairly benign. Thursday starts
with high pressure ridging stretching out from the Pacific and over
the PacNW and into the Northern Rockies/Southern Canada while a lobe
of low pressure cuts off from the main system over the Great Lakes
and retrogrades into California and Nevada. Through the weekend this
is expected to allow high pressure to eventually encompass the
entirety of the West Coast as that low pressure weakens, with a
breakdown of this deep ridge sometime late in the weekend or early
next week. Analysis of the ensemble clusters shows good agreement in
the above synoptic pattern, noting a rise in variance between the
major clusters on Sunday as the potential for a breakdown in the
ridge begins, with further variance building by Monday. Overall
there is high confidence (70-80%) in the synoptic pattern and
therefore overall forecast.

With the ridge promoting warmer than normal temperatures, Thursday
starts off around 4-8 degrees above normal. By Saturday and Sunday,
much of the region will be seeing highs around 12-16 degrees above
normal. These temperatures will see our lower elevation areas in the
widespread 80`s, with some locations even flirting with 90 degrees.
The NBM shows a 30-60% chance of highs greater than or equal to 90
for the Columbia Basin and portions of the Yakima Valley on
Saturday, with this chance increasing to 40-70% on Sunday, with even
a 5-25% creeping into the Foothills of the Blues. Highs drop around
3-5 degrees then by Monday as we see the eventual breakdown of the
ridge, but this would still be around 8-12 degrees above normal and
still remaining in the high 70`s to mid 80`s. Our first shot of
summer looks inevitable, a sign of warmth to come. Goatley/87


&&

.AVIATION...06z TAFs...Conditions are expected to improve to VFR
across all sites overnight as rain tapers off and winds start to
decrease. Some gradual clearing will take place across some sites,
with cigs becoming sct-bkn at the mid-levels, before clouds build
back in during the day Monday and winds increase once again across
all sites. Scattered showers are expected to develop in the
afternoon as well, however confidence is low as to how much of an
impact these showers will have on conditions, and whether or not
showers impact sites at all, especially outside of central Oregon
and PDT/ALW. Winds expected to be W/NW with gusts as high as 30 kts
for sites such as PDT and DLS. Shower chances will die down by late
afternoon tomorrow, and winds will finally slacken for good by
nightfall as well. Evans/74


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  57  38  57  36 /  80  60  20   0
ALW  60  41  61  41 /  80  60  20   0
PSC  64  44  66  42 /  30  30  10   0
YKM  61  38  63  37 /  20  20   0   0
HRI  62  42  64  39 /  40  30  10   0
ELN  56  39  57  39 /  20  20   0   0
RDM  51  30  51  28 /  60  40   0   0
LGD  53  36  51  34 /  90  80  40  20
GCD  51  33  48  32 / 100  90  50  20
DLS  58  44  60  42 /  60  40  10   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 5 AM PDT Tuesday for ORZ502.

     Winter Weather Advisory until 11 PM PDT this evening for ORZ509.

WA...Winter Weather Advisory until 5 AM PDT Tuesday for WAZ030.

&&

$$

SHORT TERM...91
LONG TERM....87
AVIATION...87