Richland, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

455
FXUS66 KPDT 110516
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1016 PM PDT Mon Mar 10 2025

.AVIATION...06Z TAFs...VFR conditions are will persist
through the forecast period. Winds have upticked just slightly
at PSC to 10kts but are expected to diminish overnight.
Otherwise, winds across the remaining TAF sites will remain calm
and mostly from the southwest overnight before BDN/RDM will see an
increase to near 10kts around 10AM. CIGs will be mainly above
10kft with ALW/DLS lifting around 18-20Z. Bennese/90


&&

.PREV DISCUSSION... /issued 422 PM PDT Mon Mar 10 2025/

UPDATED AVIATION DISCUSSION...

PREV DISCUSSION... /issued 248 PM PDT Mon Mar 10 2025/

SHORT TERM...This afternoon through Wednesday night...Mostly
unorganized, isolated light precipitation (lowland rain, mountain
snow) will continue through Tuesday morning as a couple weak
shortwaves pass through moist zonal flow aloft.

Active weather will return late Tuesday through Wednesday
night as an upper-level trough deepens offshore in the northeast
Pacific, shifting flow aloft to southwesterly. Ensemble NWP
guidance is near-unanimous in tracking the main attendant surface
low from offshore north-northeast into British Columbia through
Tuesday night, but does send a cold frontal boundary inland
Wednesday afternoon. Additionally, a handful of GEFS members
indicate a weak surface low developing in the Columbia Basin
Wednesday afternoon and evening.

Not much moisture transport is evident within the southwesterly
flow ahead of the cold front late Tuesday through Wednesday
morning (<250 kg/m/s penetrating east of the Cascades), so
confidence in mountain snow reaching advisory criteria is only
low-medium (30-40%) for the Cascade crest and low (<20%) for the
Blue Mountains, despite the robust trough.

Of the CAMs that extend through Wednesday afternoon, many are
advertising some modest instability (MUCAPE of up to 500 J/kg or
so) coupled with sufficiently deep CAPE profiles to allow charge
separation, low/mid-level lapse rates of 7-8 C/km, and effective
bulk shear of 35-40 kts. Thinking is some isolated thunderstorms
may develop along and ahead of the cold frontal boundary in
eastern Oregon and south-central/southeast Washington during the
afternoon, especially where orographic or frontal lift coincide.
Working against any lightning is forecast cloud cover; there is
uncertainty in how much clearing will occur Wednesday afternoon,
and forecast cloud cover is currently 60-85% across the region.
Any storms that do form will likely not produce strong outflow of
greater than 30-35 mph (limited DCAPE of up to 250 J/kg), but
some isolated rotating cells appear possible based on low-level
SRH (100+ m2/s2). Will note that no thunder has been included in
the gridded forecast since probability of occurrence at any given
point is only 5-14%. Will place confidence in at least isolated
lightning occurring somewhere in the aforementioned region at
40-70%.

Breezy to locally windy (sustained 10-25 mph) and gusty (25-40
mph gusts) southwesterly winds are forecast to develop Wednesday
afternoon across portions of central and eastern Oregon.

Wednesday night, snow levels will drop behind the cold front such
that our population centers in central Oregon will have a chance
(30-50%) of seeing measurable snow. Confidence in the lowlands in
the Columbia Basin receiving measurable snow is lower (up to
10%), but cannot be ruled out heading into Thursday morning.
Plunkett/86

LONG TERM...Thursday through Monday...A progressive weather
pattern with a series of upper level troughs will impact the
region through the extended forecast. Each system will provide
periods of moderate to heavy mountain snow, with light rain/snow
and periodically breezy conditions in the lower elevations.

Thursday begins with an upper trough quickly passing over the
PacNW and exiting to the east by early Friday morning. As the
upper trough axis approaches the Cascade crest, precipitation
rates will begin to decrease early Thursday, with most of the
lower elevation locations looking at precip chances diminishing in
the late afternoon. Light snow will continue across the Cascades
and eastern mountains into the evening, but will also briefly
diminish overnight Thursday. Confidence is moderate-high (50-80%)
in total snow accumulations between 4 to 9 inches in the Cascades
and 2 to 6 inches in the northern Blues.

Friday into Saturday, ensemble guidance is in good agreement of a
series of upper level shortwaves and a surface low impacting the
PacNW with yet another round of moderate to heavy snow
accumulations across the Cascade crest and the northern Blues.
Meanwhile, snow levels will drop to between 1kft to 1.5kft Friday
morning, resulting in light snow across central/north central OR
and the Yakima/Kittitas valleys. Snow levels will increase to
above 2kft Friday afternoon, resulting in the lower elevation
areas in WA to transition to rain; in OR snow levels will increase
to above 3kft in the early evening, resulting in a brief
transition to rain across central OR, then back to snow Friday
night. In the lower elevations, total snow accumulations will be
up to an inch (confidence 60-80%), with snow accumulations of 6 to
10 inches in the Cascades and 5 to 9 inches in the northern Blues
(confidence 50-80%). The shortwave and upper low passage Saturday
will also result in breezy winds developing across the lower
elevations, with gusts 25 to 45 mph developing in the afternoon
and evening (confidence 40-70%).

Late Saturday through Monday, ensemble guidance is in agreement
that an upper trough with a vertically stacked low circulation
will setup offshore the west CONUS, then gradually move inland
through the start of next week. However, there is disagreement
surrounding the amplitude and timing of the upper trough/low
passage. Regarding the amplitude, some cluster ensemble members
(~55%) favor a less amplified upper trough resulting in higher
rain/snow amounts across the area, while the more amplified
troughs result in heavier precipitation to the south of the
forecast area. As for timing, about 27% of the members favor an
earlier onshore arrival time of the trough axis Sunday evening and
overnight, while others keep the trough axis offshore. The earlier
arrival will result in an earlier exit and decrease in precip
chances late Monday. Overall, confidence is moderate (40-70%) that
the Cascades and Northern Blues will see another round of
moderate to locally heavy snow accumulations through Monday
morning, with light rain in most lower elevation locations and
rain/snow mix in central OR and western portions of the
Yakima/Kittitas valleys. Lawhorn/82



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  39  56  41  57 /  20  10  50  80
ALW  40  54  42  55 /  30  20  60  80
PSC  36  57  40  58 /  10   0  40  60
YKM  32  52  38  52 /   0  10  40  60
HRI  38  57  39  58 /  10  10  50  70
ELN  31  50  35  49 /   0  10  30  60
RDM  31  58  36  53 /   0  10  40  80
LGD  34  55  39  51 /  20  10  50  90
GCD  32  56  39  51 /  10  10  50 100
DLS  38  55  41  53 /  10  10  70  90

&&

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

$$

SHORT TERM...86
LONG TERM....82
AVIATION...90