Hermiston, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

212
FXUS66 KPDT 221200
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
400 AM PST Mon Dec 22 2025

.DISCUSSION...

Southwesterly flow will prevail across the Pacific Northwest today
as one system exits the region. Drying will move over the area and
the only precipitation expected will be over the Cascades.

Another weak system will bring a renewed shot of light snow over
the Cascades tonight but amounts should be around 2 inches at
pass level. The remainder of the area will remain dry into
Tuesday. However, later Tuesday, moisture will move up from the
south and bring precipitation to the southern highlands and Blue
Mountains and Wallowa Mountains. This moisture will then move
northwestward across the region.

In the meantime, additional moisture will move north from
California during the day on Wednesday. Most areas will see at
least some precipitation, with the mountains getting snow and the
lower elevations receiving rain. By Wednesday afternoon into
Wednesday night, the moisture moves out and most areas will dry
out. Then there is at least another shot of precipitation...albeit
lighter...across the area on Christmas Day, as a low moves
northward off the California and Oregon coasts then moves inland
and weakens and eventually dissipates.

It is possible that additional winter weather headlines may be
needed for the Washington Cascades, especially at some point for
the Tuesday night Wednesday time frame, depending on what later
guidance shows, However, right now, guidance is below winter
weather advisory thresholds...generally around 3 inches. Also, it
is possible, if not probable that there will be light < 1 inch
accumulation in the Kittitas Valley and nearby areas, and on
Friday in the Wallowa Valley.

Precipitation chances linger into Friday...light in the lower
elevations and a bit heavier for the mountains...but by later
Friday, high pressure will build in from the west and
precipitation will come to an end with dry weather expected for
the weekend.

On Wednesday, as pressure gradient strengthens due to a surface
low moving northward off the coast, winds are expected to
increase. There is still some uncertainty as to just how much.
Some of the guidance is stronger than others, but there is a
possibility of gusty winds, especially across the elevated
terrain, and wind headlines may ultimately be needed. The ECMWF
EFI is not especially focused on any specific area at this time.
It just has 0.8 to 0.9 anomalies across a wide swath of western,
south- central and a portion of eastern Oregon.

&&

.AVIATION...
12Z TAFS...VFR conditions are expected through the TAF day today with
the area of rain that affected some TAF sites earlier moving out.

The next system will move across the region late tonight, and will
bring renewed RA chances to DLS and YKM with MVFR conditions from
around 23/06Z onward. Everywhere else will remain VFR through the
period. Winds should be 10 kts or less through the period, at all
sites except BDN and RDM, which may see some gusty winds to around
20 kts this afternoon, before they return to 10 kts or less for
the remainder of the period.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  49  33  45  34 /  10   0  30  60
ALW  49  37  45  38 /  20  10  40  70
PSC  49  32  45  35 /  10   0  10  80
YKM  41  28  41  32 /   0  30   0  70
HRI  49  32  44  34 /  10   0  20  70
ELN  37  24  36  29 /  10  40   0  70
RDM  47  25  44  29 /  10   0  30  50
LGD  44  32  43  37 /  30  10  70  40
GCD  46  33  46  38 /  20  10  90  40
DLS  46  36  44  37 /  20  60  10  80

&&

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

WA...None.

&&

$$

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