Storms West of Butte Load Up for 80 MPH Supercell Gusts, Large Hail — SevereWX

Isolated strong thunderstorms are developing west of Butte near the Montana-Idaho border, fueled by a plume of monsoonal moisture on the edge of a massive mid-level ridge and stronger flow from an upper low over southern British Columbia.

The Storm Prediction Center's Mesoscale Discussion 1651 highlights favorable conditions: moderate instability with MLCAPE of 1000-1500 J/kg and 35-45 knots of southwesterly shear supporting supercell and multicell structures. As of 1930Z, storms were already ongoing in this fringe zone.

Primary Threats:

• Damaging Winds: Most probable 65-80 mph, with potential exceeding 75 mph as the main hazard.
• Large Hail: Up to 1.75 inches possible in any persistent supercells.

Coverage remains the key uncertainty—isolated to widely scattered at best—with SPC assigning a 40% chance of issuing a Severe Thunderstorm Watch through 2100Z. Trends will be closely watched this afternoon and early evening.

Areas at risk span western Montana into central Idaho. Check the SPC graphic for exact lat/lon details.

Preparedness: If you're in the path, secure outdoor items, monitor local NWS radar updates via WFO Missoula (MSO) or Great Falls (TFX), and have a shelter plan ready for sudden severe gusts or hail. Stay weather-aware.