Pendleton, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

582
FXUS66 KPDT 132354
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
454 PM PDT Tue May 13 2025

.Updated for Aviation...


SHORT TERM...Today through Thursday...Current satellite and radar
imagery shows mainly low clouds across the forecast area.

The upper trough moves further eastward as the leading edge of the
ridge approaches to the PacNW. With the SPC Outlook keeping our
northeast area in general risk, isolated thunderstorms could develop
over the eastern mountains (mainly the Wallowas) this afternoon into
the evening (<30% chance). The moisture level is relatively moderate
with steep lapse rates (>6.5 C/Km) to fuel the storms, but weak
instability may hinder their severity and longevity. Showers will
progress more over to the mountain areas as the lowlands gradually
dries. QPF amounts will be up to 0.50 inches over the eastern
mountains and OR Cascades with less than 0.10 inches across the
Blues and the upper parts of the Columbia Basin. With the increased
northeasterly flow, the Cascade Gaps will remain gusty up to 30-40
mph through the rest of today.

The ridge then builds over the PacNW tomorrow with the northwesterly
flow aloft. Showers may linger over the Wallowas whereas the WA/OR
Cascades could receive more precip from the frontal system (30-40%
chance). QPF amounts will be less than 0.10 inches at the
aforementioned areas, leaving the lowlands dry. Dry conditions may
continue tomorrow evening through night. Wind gusts (25-35 mph) will
develop across the Cascade Gaps tomorrow morning. Gusts might reach
to 40 mph around the Columbia Gorge but, confidence is low (<30%)
on the extent.

Thursday, showers could return starting late morning at the Cascades
first and then spread across most of the forecast area for remaining
day. Winds will become breezy again over the Cascade Gaps up to 15-
25 mph. Feaster/97

LONG TERM...Friday through Tuesday...An unsettled weather pattern
highlighted by an upper trough crossing the area Friday night
through Sunday evening is expected through the long term period.
Models are in fairly good agreement through most of the long term
period though differences arise about the location and strength of
an upper low in the base of the trough by Sunday and increase about
whether another trough can flatten an offshore ridge enough to
arrive in our area late Monday night and Tuesday.  The Extreme
Forecast Index highlights winds Sunday over most the area but
highest over the Cascade gaps and eastern Oregon mountains with
values of 0.88 for sustained winds and 0.86 for wind gusts. It has a
Shift of Tails over the areas mentioned above suggesting that a
minority of model ensemble members have even higher winds. Winds
remain highlighted Monday with values of 0.78 for both winds and
wind gusts though this time without a Shift of Tails. It also
highlights QPF over the eastern mountains Saturday with a value of
0.68 and then with a value of 0.83 with a Shift of Tails over the
northern Blue Mountains and Wallowa County on Sunday.

Models agree in having a shortwave leaving the area Friday morning
with showers over the Washington Cascades and eastern mountains
tapering off in the afternoon. Rain amounts will be just a few
hundredths of an inch. Highs will be in the mid 60s to lower 70s
with mid 50 to lower 60s in the mountains. Friday night, models
agree in having a trough come ashore and move overhead Saturday.
This will give the entire area rain showers with a slight chance of
afternoon thunderstorms over the eastern mountains. The eastern
mountains will receive the brunt of the precipitation with a half
inch to an inch of rain over the northern Blue Mountains and Wallowa
County while the rest of the mountains will get a quarter to half
inch. The Blue Mountain Foothills get up to a quarter inch but the
rest of the area will receive less than a tenth of an inch.
Temperatures will be down 2 to 5 degrees from Friday. Winds through
the Cascade gaps will reach 20 to 25 mph with gusts to 35 mph in the
afternoon.

Models agree in having a low develop in the trough Saturday night
and by Sunday having the low either overhead or to the east. Either
way, circulation around the low will keep rain showers over the
northern Blue Mountains and Wallowa County with amounts up to a
quarter inch. Elsewhere, rain will be very light generally, though
up to a tenth of an inch in the Washington Blue Mountain Foothills.
Temperatures will be similar to Saturday. With a ridge building off
shore and the low to the east, winds will be highest Sunday with
west to northwest winds in the Cascade gaps reaching 20 to 30 mph
with gusts to 40 mph in the afternoon while the rest of the area is
at 15 to 25 mph.

On Monday, models have the low somewhere over the Rockies while the
offshore ridge brings a drier northwest flow over the area. This
generally keeps the forecast dry though a slight chance of some
upslope showers will be possible along the Cascade crest and
eastern mountains with barely measurable amounts. As mentioned
above, models struggle with a shortwave arriving Monday night and
Tuesday. 56 percent of the model ensemble members flatten the ridge
enough to allow the shortwave to move into our area while the other
44 percent keep the ridge strong enough to send the shortwave to our
north. The NBM keeps a chance of rain showers with very light
amounts over the Cascade crest and mountains of northeast Oregon and
this seemed to be a good compromise. Models keep the breezy to windy
conditions over the area both Monday and Tuesday with speeds just a
few mph lighter than Sunday. With the ridge replacing the departing
low, temperatures Monday rise 4 to 8 degrees to the upper 60s to mid
70s with 60s in the mountains and remain that way Tuesday.
Perry/83

AVIATION...
00Z TAFS...VFR conditions expected through the TAF period. Gusty
winds will continue at DLS and remain in the 25 to 30 kt range.
Elsewhere, gusty winds at BDN and RDM will decrease this evening
and all sites will mainly be 10 kts or less. However all
locations will gust to around 20 kts Wednesday afternoon.



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  45  67  41  66 /  30   0   0   0
ALW  47  66  43  66 /  30  10   0   0
PSC  45  72  41  71 /  20   0   0   0
YKM  45  71  41  69 /  10   0   0   0
HRI  46  71  41  70 /  20   0   0   0
ELN  45  64  41  65 /  10   0   0   0
RDM  35  61  31  64 /  10   0   0   0
LGD  43  58  37  63 /  40  10   0   0
GCD  40  57  34  64 /  60  10   0   0
DLS  47  66  44  64 /   0  10   0   0

&&

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

$$

SHORT TERM...97
LONG TERM....83
AVIATION...77