National Weather Service in Billings Releases Preliminary Findings on Monday’s Devastating Storm

I have a friend in Shepherd, and when I first heard what tore through her area early Monday morning, my stomach dropped. What she's dealing with right now is devastating, and she's far from the only person in the Shepherd area cleaning up after the storm.

Timeline of the September 7 Storm Near Shepherd, Montana

Here is how the storm unfolded, based on the preliminary findings released by the National Weather Service in Billings.

Between 2 and 3 a.m. Monday, September 7, a storm moved through Billings and intensified as it traveled toward the Shepherd vicinity.

At Billings Logan International Airport, gusts reached 53 mph, and 1.29 inches of rain fell in just half an hour. As the storm moved into the Shepherd, Huntley, and Worden areas, it quickly strengthened and produced hail measuring up to three inches in diameter.

That is roughly the size of a large apple. Let that sink in.

The National Weather Service had been watching the possibility of severe weather since the day before. On Sunday, September 6, forecasters warned that isolated severe thunderstorms could develop overnight. Strong winds, locally heavy rain, and hail were all listed as possible threats.

At 2:11 a.m. Monday, the National Weather Service issued a Special Weather Statement for the Billings and Shepherd areas. It warned of wind gusts reaching 55 mph, small hail, and heavy rain.

A follow-up Special Weather Statement was issued at 2:44 a.m. for Shepherd and Worden. Wind gusts reaching 55 mph and heavy rain remained possible, while the expected hail size increased to around the size of a nickel.

By 2:50 a.m., a Flood Advisory was in place for Billings Heights, Shepherd, and Acton. By then, an estimated 1 to 2.5 inches of rain had already fallen, with another inch possible.

Three Inch Hail Causes Serious Damage Near Shepherd

If you're in Shepherd, you already know what this part of the story looks like.

The National Weather Service’s preliminary report confirms what many people woke up to Monday. Strong winds and large hail shattered windows in homes and vehicles, knocked down power lines, and caused outages. In the worst cases, vehicles were totaled, and sheds were blown over.

The highest observed wind gust was 64 mph, recorded three miles southwest of Lockwood. Hail measuring up to three inches in diameter was reported in the Shepherd vicinity, while smaller hail fell elsewhere in and around Billings.

Why the Shepherd Storm Intensified So Quickly

If you are wondering why the Shepherd area was hit so much harder, the National Weather Service’s radar analysis helps explain what happened.

As the storm moved through Billings, radar detected winds of 60 to 70 knots just east of town at approximately 1,000 feet above ground level. Radar also showed signs of very high rainfall rates and a large amount of small hail.

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As the storm moved out of the Billings Heights area, a hail signature began forming on radar. That prompted the National Weather Service to increase the potential hail size in its follow-up Special Weather Statement.

By the time the storm entered the Shepherd vicinity, it had rapidly intensified. Several hail signatures increased sharply over just a few minutes. According to the National Weather Service, this was likely when the three-inch hail fell.

The storm quickly weakened again after leaving Shepherd, but it continued producing strong winds, heavy rain, and small hail as it moved out of the area.