Winner, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

646
FXUS63 KUNR 071745
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1145 AM MDT Sun Jun 7 2026

.KEY MESSAGES...

- A cold front will move slowly across western South Dakota
  tonight, bringing chances for showers and thunderstorms. Severe
  severe storms are possible, especially over northwestern South
  Dakota.

- Cooler Monday, then hot again Tuesday.

- Slight chance for storms Monday, with higher chances for storms
  Tuesday night and Wednesday.

&&

.DISCUSSION...(This Afternoon Through Saturday)
Issued at 1143 AM MDT Sun Jun 7 2026

Upper level analysis has a low over Alberta with a trough extending
through the northern Rockies into the Desert Southwest. At the
surface there is an area of low pressure over western North Dakota.
A cold front extends southward from the low along the Montana/South
Dakota border, into northeastern Wyoming, and down into northern
Utah. This cold front will be the focus for convection later today.

Thunderstorms will form early this afternoon over northeastern
Wyoming and move northeastward through the evening. Steep lapse
rates, SB CAPE of 1500-2000 J/kg, and 0-6 km shear is 30-40 kts,
indicates the possibility of severe storms later today and into the
evening. However, the more favorable parameters for severe storms
will likely be located further north - closer to the Montana/North
Dakota border. As the potential for severe storms wane by late
evening, scattered showers and storms will continue overnight across
much of western South Dakota behind the cold front.

On Monday, it will be cooler with highs in the 70s to low 80s.
Surface high pressure will slide through the CWA, resulting in
increasing southeasterly winds of 15-25 mph during the afternoon
over the northeastern Wyoming and far western South Dakota plains.
Another hot day is ahead on Tuesday with prefrontal warming and
gusty southerly winds. Highs will be back in the 90s. Due to the
greenness from the recent rain, the NBM high temperatures are most
likely a few degrees too high. Another cold front will move through
the area late Tuesday and Wednesday, resulting in a chance for
scattered storms, some of which may be severe closer to central
South Dakota. Temperatures for the second half of the week will be
closer to seasonal averages.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1143 AM MDT Sun Jun 7 2026

Isolated to scattered, potentially severe, thunderstorms will
develop over northeast Wyoming early this afternoon before moving
over southeast Montana and northwest South Dakota this evening
and into the overnight hours. Large hail, frequent lightning, and
gusty/erratic winds can be expected with any stronger convective
cores. Transient MVFR/IFR conditions also expected around any
heavier precipitation cores. Conditions will improve between
05-07z as storms/showers move out of the region.

&&

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

$$

DISCUSSION/KEY MESSAGES...MLS
AVIATION...CAS