Thunderstorm Wind — Fergus, Montana

2025-08-07 · near Grassrange Clark Arp, Fergus, Montana

Event narrative

Weather underground station near Grass Range.

Wider weather episode

An embedded wave within more broad troughing digging into the Pacific Northwest moved across the region late night August 6 into August 7. Elevated instability increased as showers and thunderstorms moved eastward from Central Montana toward Fergus county. As these thunderstorms continued to balloon and cross Lewistown Divide, they became severe, producing a wide swath of gusts in excess of 55 mph, including a peak gust of 71 mph just east of Lewistown Divide.

Later in the day ample instability and shear developed across Fergus county again to result in an instance of large hail near Grass Range.

View location on OpenStreetMap → (47.0500, -108.8400)

Source: NOAA Storm Events Database, event_id 1287565. Narrative written by the NWS forecast office that issued the report.