Area Forecast Discussion

KEY MESSAGES

- Hot weather will continue this week with highs in the 90s.

- Thunderstorms will be possible at times this week. Main threat with storms will be gusty winds.

UPDATE

Issued at 1026 PM MDT Sun Jul 26 2026

KUDX radar shows a line of storms stretching from just east of Hulett to Upton through south central Weston County. Surface obs are showing 40-55 kt winds with this line. These storms/strong winds are expected to subside over the next hour or two as they cross the Black Hills. A few of the latest CAMs are showing isolated elevated storms overnight, but believe most locations will stay dry through sunrise. Suface obs are also showing a cool front crossing Tilford toward Elm Springs and along the Cheyenne River Valley. NE surface winds behind the front are drawing in smoke from MT/ND (originally from the Northern Rockies region). Smoke is expected to linger mainly across NW/Central SD through Monday. Temps will once again be hot on Monday, but slightly cooler than Sunday. Apparent temps don't make it to advisory criteria, so at this point will not be reissuing any heat-related headlines. CAMs are in agreement that a shortwave now over UT will push into the CWA late Monday. MLCAPE will be in the 500-1000 J/kg range across NE WY into the Black Hills. It increases to 2500 J/kg over the western to central SD plains where dewpoints will be around 60F. Storms are expected to initiate over the Bighorns to NE WY in the early afternoon where CIN is very weak. Outflows/upper forcing will then propogate toward the Black Hills and western SD plains through the mid afternoon to early evening hours, allowing for futher convective development as it overcomes the cap. Shear is weak over NE WY but is moderate over western SD, so could see some strong to severe storms east of the Black Hills. Though, with the dry boundary layer, can't rule out strong wind gusts from storms over NE WY, either. With the incoming monsoonal moisture, GFS shows PWATs at 150-175% of normal, so some storms could have heavy rain.

DISCUSSION

(This Afternoon Through Saturday) Issued at 1154 AM MDT Sun Jul 26 2026

Upper level ridge will remain anchored over the Rockies into the Plains supporting hot temperatures through this week. The FA will remain on the northern periphery of the ridge with impulses traversing the flow. This will support near daily chances for TS as monsoon waves traverse the region. Week sfc trough has advected through the FA today with winds shifting northerly. This has knocked temps down a few degrees from yesterday, but still very hot. Weak capping over the BH with sufficient moisture will allow a few shra/ts to develop there this afternoon. Main focus will be the next impulse expected to support TS this evening in the west. TS will develop across WY and push east into the western FA this evening. High based nature will support gusty winds as the storms push east. As the wave progresses through the FA overnight, sct- isold shra/ts will be possible, mainly across the north. Hot Monday with temps in the mid to upper 90s once again. The next wave will arrive late afternoon/early evening and support TS across the western half, possibly earlier over the BH if subsidence behind tonight's wave has pushed east. Again, gusty winds will be the main threat from TS given continued high based nature. Same for each day the rest of the week, daily chances for shra/TS as monsoon moisture continues to advect around the backside of the ridge. Most days will see isold-sct activity given lack of strong forcing and high based nature of storms. However, a stronger wave may bring slightly better coverage of storms Wed into Thur if timing works out right. Otherwise, a break in this pattern and heat is not expected until early next week with a stronger northern stream shortwave flattens the ridge and supports a decent cold front into the Northern Plains.

AVIATION

(For the 00Z TAFS Through 00Z Monday Evening) Issued At 530 PM MDT Sun Jul 26 2026

Isolated to scattered thunderstorms are expected this evening and overnight across NE WY and W SD. The storms this evening may have gusty, erratic winds up to 45 kt. Otherwise, VFR conditions are expected through the forecast period. Wildfire smoke will move into the area Monday, especially across the northwestern and central SD plains, though at this time visibilities are expected to stay VFR.

UNR WATCHES / WARNINGS / ADVISORIES

SD...None. WY...None.