Hermiston, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

631
FXUS66 KPDT 021703
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1002 AM PDT Wed Apr 2 2025

.UPDATED AVIATION...18Z TAFs...VFR conditions will persist
through the forecast period with CIGs ranging between FEW and BKN
7kft to 10 kft. Gusty winds will affect TAF sites
DLS/BDN/RDM/PDT/ALW currently and will continue through 02-04Z
with sustained winds of 10-17kts and gusts between 15-25 kts. 90


&&

.PREV DISCUSSION... /issued 409 AM PDT Wed Apr 2 2025/

SHORT TERM...Today through Friday...Although there are
some weakening showers outside of our area, satellite and radar
imagery do show overcast clouds over the Blues and Lower Columbia
Basin, but cleared out for central OR. And with the northwesterly
flow aloft along the WA/OR Cascades, the cold dry air being pushed
will assist in decreasing cloud coverage in that area. This will
also help slightly lower the temperatures over the Cascades and east
slopes as well. Low temperatures will remain slightly warmer for the
Blues and Lower Basin from the increased cloud coverage.

As a trough gradually moves out of our area, mountain snow will
remain through this morning over the Blues and WA/OR Cascades with
accumulations up to an inch (<30% chance). Isolated thunder may
occur over the eastern mountains (mainly the Wallowas) into this
afternoon as well with a 30-40% chance, but instability is weak
(CAPE under 500 J/Kg). Otherwise, the forecast area will be dry
through the rest of today. Due to the westerly flow, gusty
conditions (25-35 mph) continue for the Kittitas Valley and the
foothills of the Blues this morning before decreasing this evening.

Tomorrow, an upper ridge will be over the PacNW, bringing in dry
conditions over the lowlands with lingering mountain snow for the
morning. Isolated thunder may return tomorrow late morning into
afternoon across the eastern mountains with a 10-20% chance but,
confidence is low due to weak instability. Through the remaining
day, winds will return to being breezy again up to 25 mph at the
Foothills of the Blues, Kittitas Valley, Cascades and Northern Blues
from the increased northwesterly flow. Tomorrow night onwards,
Kittitas Valley and Grand Ronde Vally may see some occasional
breeziness but other than that, winds should be light across the
forecast area. Friday, breezy winds might return over the Foothills
of the Southern Blues and the crest of the Cascades in the afternoon
hours. However, confidence is low on its longevity. Feaster/97

LONG TERM...Saturday through Wednesday...Only real feature to note
in the long term is an upper-level wave that models key in on around
the Sunday night to Monday morning time period. This wave is
associated with a broader low and will orient winds aloft to the SW
across the forecast area, bringing a shot of moisture to all areas,
particularly over the eastern mountains.

Models seem to be a bit more aggressive on the moisture associated
with this system. Looking at deterministic global models, this
appears to be because both the GFS and ECMWF depict a more potent
wave coming through the PacNW, which would lead to greater moisture
transport and lift. NBM probabilistic guidance now suggests about a
30-45% chance of QPF above 0.2 inches across the northern Blues, and
a 50-60% over the Cascade crests. Not overtly impressive given the
time of year, but given the oncoming warmth, is expected to lead to
river and stream rises, which is reflected across the latest RFC
forecasts. Snow levels will be much too high for any real snow
threats to be considered (>6000 ft), but some isolated thunderstorms
are not out of the question, especially as this wave develops more
of a negative tilt. Global models don`t tap into instability just
quite yet, and the nocturnal timing isn`t ideal, but based on
pattern recognition alone, the possibility should at least be
mentioned (10-20% confidence at this time).

Otherwise, ridging will dominate before and after this system,
allowing highs to climb well into the 60s across our lowlands and
population centers. Winds will also pick up as we transition between
systems, but as of now, particularly gusty winds do not appear to be
a concern at this time. Evans/74



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  54  34  56  33 /   0   0  10   0
ALW  54  36  55  36 /  10   0  30  10
PSC  60  34  61  33 /   0   0  10   0
YKM  58  33  60  34 /   0   0   0   0
HRI  59  34  60  33 /   0   0  10   0
ELN  54  34  57  32 /   0   0  10   0
RDM  50  26  53  26 /   0   0   0   0
LGD  48  29  49  28 /  10   0  20  10
GCD  46  28  49  26 /  30   0  20  10
DLS  57  36  61  36 /   0   0   0   0

&&

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

$$

SHORT TERM...97
LONG TERM....74
AVIATION...90