National Weather Service United States Department of Commerce


Numerous severe thunderstorms moved through northwest and north central North Dakota from the evening of Monday, July 18th, 2022, through the early morning of Tuesday the 19th. A surface low and cold front moved through eastern Montana and into western North Dakota ahead of a strong upper level disturbance, in an environment with strong instability and wind shear that was supportive of severe thunderstorms. There were a few rounds of thunderstorms as the surface low and cold front moved through, with some locations in the northwest being impacted by multiple thunderstorms through the evening and overnight. A few locations had higher end severe thunderstorms, with very large hail and damaging straight line winds reported. 

Very large hail fell in the city of Williston late in the evening, with numerous reports of hail from golf ball to tennis ball size (1.75 - 2.5 inches in diameter). There were a few hailstones measured at 3 inches in diameter, which set a new record for the largest hailstone recorded in Williams County. 

Some of the more significant damage from the Wildrose area included numerous large trees uprooted and some snapped, damage to outbuildings, downed power lines, and sheet metal walls blown into vehicles, campers, and motorhomes. Straight line winds were estimated around 95 mph in this area. 

Damage just north of Belcourt included partial loss of roof materials on a home, damage to outbuildings and lawn decorations, and broken tree branches. Straight line winds were estimated around 75 mph in this area. 

WFO Bismarck would like to thank the Williams County and Rolette County emergency managers for their help in collecting damage reports and photos, as well as members of the public who submitted reports and photos through social media. 

Wildrose damage

Photo credit: Watterud Latoya


A compact shortwave was approaching North Dakota on the evening of July 18th, with lift ahead of the wave interacting with a surface low and associated warm and cold fronts. An Enhanced Risk (level 3 of 5) was introduced by SPC on the morning of the 18th, with increasing confidence in the potential for severe thunderstorms as these features approached a moisture-rich air mass. Dew points were in the upper 60s to mid 70s which increased the available instability for thunderstorms. 

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Figure 1: Surface map, valid July 18th 10 PM CDT Figure 2: 500mb height map, valid July 18th 7 PM CDT Figure 3: SPC Day 1 Outlook that included an Enhanced Risk (Level 3 of 5) for severe storms over northwest and north central North Dakota.

These images help illustrate the near-storm environment at 10 PM CDT, with the highest magnitude severe reports in the 10 PM to midnight timeframe. In northwest North Dakota, MLCAPE was in the 3000-3500 J/kg range, overlapping with 0-6 km shear of 50 knots and mid-level lapse rates of 8.5°C/km. This was an environment very supportive of not just severe thunderstorms but higher-end storms as well, which was proven by the reports of 3 inch hail in Williston, and the estimated 95 mph straight line winds in Wildrose. Images from SPC Mesoanalysis Archive.

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Figure 4: MLCAPE (contour) and MLCIN (shaded), valid July 18th 10 PM CDT Figure 5: Surface to 6 km bulk shear vector, valid July 18th 10 PM CDT Figure 6: 700-500mb Lapse Rates, valid July 18th 10 PM CDT


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