On Wednesday, July 6, there were several observations of a funnel cloud near Raynesford and Geyser in Judith Basin County.
At the time the funnel cloud was spotted, a severe thunderstorm was passing through the area with quarter-sized hail and wind up to 60 mph.
For a funnel cloud to form, there needs to be air spinning horizontal in relation to the ground, which is typically caused by wind shear. Wind shear is when there is a difference in wind speed and/or wind direction with height over a relatively short distance.
When the thunderstorm moved over this spinning air, it stretched the spinning air out into a vertical column. The rotation of the air then increases, and condensation begins to occur, which forms the funnel cloud.
If a funnel cloud actually makes contact with the ground, then it becomes a tornado.
Montana's tornado season generally spans from late May through early August. Most Montana tornadoes are relatively small and usually touch down in sparsely-populated areas – but not always.
In 2016, an EF-3 tornado hit the town of Baker in southeast Montana. In 2015, a small tornado hit near Sidney in Richland County in eastern Montana, injuring one person and causing some damage. In June 2010, a tornado hit Billings, causing significant damage to the MetraPark facility. Just several weeks later, two people were killed when a tornado struck a family ranch near Reserve in northeastern Montana.