On Saturday (June 17th), the sixth anniversary of the 2010 Northern Plains tornado outbreak occurred. This was a fairly wild tornado outbreak, as it produced well over 50 tornadoes across North Dakota, Minnesota and western Wisconsin.
The system was very dynamic in nature, which may be surprising because of the time of year, but it wasn’t too crazy. The jet stream tends to shift northward in the summer time, and that is when the northern states see a peak in their severe weather season.
A shortwave trough that day ejected out of the northern Rockies, and into the northern plains. The 500 mb mid-level jet propagated into the region with greater than 50 knots of southwesterly flow, in addition to the region being in the exit region of the jet streak (this is a favorable region for vertical motion in the atmosphere).
This forced strong responses at the 700 and 850 mb levels, with near 50 knots of southwesterly and south-southeasterly flow (respectively) forming at each level. This created a highly sheared environment across the northern plains, evident by soundings across the region.
Additionally, within a warm and moist boundary layer (surface to about 1.5 km off the ground), the atmosphere became very unstable into the afternoon, yielding an atmosphere that was very primed for tornadoes and severe thunderstorms.
The atmosphere was relatively uncapped into the afternoon, so many of the supercells congealed into more linearly driven convective mode; however, clusters of supercells continued to produce tornadoes. There were 7 EF-4’s and EF-3’s, and this was one of the larger outbreaks in Minnesota’s history.
This event actually fascinates me, as most severe weather meteorology does (you may have realized that at this point). This was a unique system, and is really interesting to study. Check out some of the videos from the event itself.