144
FXUS63 KUNR 012111
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
211 PM MST Mon Dec 1 2025

.KEY MESSAGES...

- Mild/seasonal temperatures Tuesday. Cold Wednesday. Back to
  mild and seasonal temperatures Thursday and Friday.

- Highest chances of accumulating snow will be over the northern
  Black Hills and Bear Lodge Mountains. Less than an inch of snow
  expected on the plains.

&&

.DISCUSSION...(This Evening Through Monday)
Issued at 205 PM MST Mon Dec 1 2025

Water vapor and upper level analysis show a longwave, positively
tilted upper trof extending from the Northern Plains into the
southern Rockies and southern High Plains. Additionally, a shortwave
ridge extends into the Pacific Northwest with a shortwave trof
immediately behind it in the Gulf of Alaska. At the surface, a warm
front extends through central South Dakota, allowing temperatures at
20Z to range from the mid to upper 30s behind the warm front to the
teens for locations ahead of the front. Some of the heavier snow
covered areas are still sitting in the 20s.

For tonight, warm front will slowly progress eastward as a surface
low over Alberta begins to dive southeastward through Saskatchewan.
Low temperatures tonight behind the warm front will be around
average, in the mid teens, while single digit lows will continue
across the far eastern portions of the forecast area.

Tuesday/Wednesday, the upper trough moves through the Canada Prairie
Provinces into the Great Lakes, pushing a cold front through almost
the entire forecast area by 12Z Wednesday. Upper level energy
splits, with the main forcing passing north and south of the area.
However, weak forcing and modest moisture and frontogenesis should
allow for some light rain and snow across the area. With northwest
flow aloft, the northern Black Hills and Bear Lodge Mountains should
be able to pick up higher snowfall amounts due to upslope
conditions. Model ensembles range from 1 to 6 inches, with the 25th
to 75th percentiles in the 2 to 4 inch range. With a longer duration
of light snow and the max 6 hour snow accumulation 1.5 inch or less,
will forgo any winter weather headlines at this time. As for
temperatures, Tuesday will once again be mild ahead of the cold
front, but Wednesday will be cold, with highs only in the teens and
20s.

Active northwest flow continues through early next week, with
additional disturbances Thursday night and Friday, and another
Saturday and Saturday night. With all of these systems, the northern
Black Hills and Bear Lodge will be the favored area for the highest
precipitation amounts. As for temperatures, 850 temperatures stay at
or above 0C for Thursday and Friday, drop to -5C late
Saturday/Saturday night, then begin to warm to 0C to 5C early next
week.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Tuesday)
Issued At 955 AM MST Mon Dec 1 2025

VFR conditions will prevail through the period.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...Smith
AVIATION...Smith