658
FXUS63 KUNR 091128
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
528 AM MDT Mon Mar 9 2026

.KEY MESSAGES...

- Cold front will bring cooler temperatures on Monday.

- Snow accumulation possible Tuesday especially across the Black
  Hills.

- Cooler, unsettled weather for the second half of the week.

&&

.DISCUSSION...(Tonight Through Sunday)
Issued at 941 PM MDT Sun Mar 8 2026

Upper air analysis shows west/northwest flow aloft extending from
the Pacific NW coast through the northern Plains into the Great
Lakes. Several shortwaves are crossing the region, bringing plenty
of clouds to the northern half of the CWA into ND and MT. Surface
obs shows low pressure crossing eastern ND with a cold front pushing
south behind it. The front has reached I-94 in ND and will continue
into the CWA after 06z tonight before stalling over west central SD
Monday morning. This will lead to a 30 degree range of max temps on
Monday, with highs in the 40s over NW SD to low 70s across SW SD. A
surface low will develop across the CWA midday tomorrow and slide
eastward through SCentral SD through the afternoon. Northerly winds
will increase behind the low, pushing the front south of the
forecast area Monday evening. Light rain/snow will be possible
across NW SD late tomorrow, but QPF will be minimal. Upper
jet/shortwave trough will cross the Intermountain West and push
through the CWA on Tuesday. A secondary front will cross the CWA,
bringing rain and snow to the the western SD plains...and snow to
the Black Hills and NE WY. There is some model inconsistency as to
snow amounts since much of this will be dependent upon afternoon
temps, which is also when the strongest forcing/highest QPF will
occur. It will also depend on how quickly temps fall behind the
front in the evening. Current thinking is snow accumulation will be
possible over the plains, but snow totals will be light...around an
inch or so. Higher amounts are expected across the Black Hills where
surface temps will be near or below freezing. Could see anywhere
from 2 to 5 inches by late Tuesday evening. This winter, models have
has a history of trending drier as we get close to the event, so
will see if that happens again or if headlines (advisories) will be
needed for the Black Hills. Upper ridging takes over the western
half of the CONUS toward midweek, bringing a warming trend Wed and
Thu. Highs on Thursday could reach the 60s and 70s, but then a cold
front will cross the area at some point late in the day, bringing
strong winds (gusts to 60 mph) and rain changing to snow in the
evening. Unsettled weather will remain across the area through the
end of the week into next weekend, with chances for snow.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Tuesday Morning)
Issued At 517 AM MDT Mon Mar 9 2026

A cold front will bisect the area today, moving back and forth
from KGCC to KRAP/KIEN. Behind it, a narrow band of IFR CIGS this
morning will dissipate this afternoon leaving VFR conditions for
this afternoon. Local MVFR CIGS will develop later tonight as the
cold front moves south of the forecast area. Patchy light
rain/snow may occur near the ND/SD border today and then north of
I-90 tonight.

&&

.FIRE WEATHER...
Issued At 155 AM MDT Mon Mar 9 2026

Rapidly changing fire weather conditions are expected this week.
A cold front will bisect the area today with cooler, less dry air,
and north to northeast winds at 15-25 mph behind it, generally
north of I-90. Ahead of the front, very dry air (minimum relative
humidities as low as 14 percent) will develop along with gusty
west winds at 15-30 mph with gusts from 30-45 mph. HREF joint
probabilities indicate ~50% chance of Red Flag Warning criteria
(15% MinRH, wind >25 mph), but the dynamic nature of the strong
downslope and well-mixed west winds give higher confidence in
sensible weather this afternoon. The result will be elevated fire
weather conditions behind the front and critical fire weather
conditions ahead of the front for fire weather zones 315, 317, and
322.

Expect increasing chances for snow later tonight and Tuesday as a
disturbance moves through the region with the best chance of
wetting precipitation for the Black Hills, perhaps several inches
of snow.

Elevated fire weather conditions return Wednesday, but critical
fire weather conditions may develop Thursday with a sharp warm up,
very dry air, and wind gusts potentially exceeding 50-60 mph.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning from noon today to 6 PM MDT this evening for
     SDZ322.
WY...Red Flag Warning from noon today to 6 PM MDT this evening for
     WYZ315-317.
&&

$$

DISCUSSION/KEY MESSAGES...13
AVIATION...Helgeson
FIRE WEATHER...Helgeson