Sixth Anniversary of Infamous Tornado Outbreak was Saturday

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 tracks of the tornadoes on June 17th, 2010. h/t SPC

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.

This is the tornado climatology/probability for the US for tomorrow. This shows the northward trend throughout the summer in Tornado climatology. h/t SPC

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).

The 500 mb analysis at 20z on June 17th, 2010. This shows the strong flow across the northern plains, with the arrows representing the divergent flow. h/t SPC

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.

The 700 mb analysis at 20z on June 17th, 2010. This shows the strong flow tha tresulted from divergent flow in the mid and upper levels of the atmosphere. This helped create a well sheared environment. h/t SPC

The 850 mb analysis at 20z on June 17th, 2010. This shows the strong flow that resulted from divergent flow in the mid and upper levels of the atmosphere. This created a well sheared atmosphere. h/t SPC

This is the 0-3 km Storm Relatively Helicity, which just measures the potential for a helical motion for updrafts (aka potential for rotating updrafts). This is a good indication of how high the tornado threat is with storms in that environment. The numbers are hiiiiiigh in the northern plains that day. h/t SPC

This is the hodograph from the International Falls, Minnesota sounding at 00z on June 18th, 2010. This graph and the numbers in the box show an incredibly sheared environment. h/t SPC

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.

CAPE, which is a measure of instability, was very high across the northern Plains during the event, leading to strong updrafts and severe thunderstorms. h/t SPC

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.

The development and evolution of the event on radar. h/t UCAR Archive

The evolution of the event on satellite imagery. h/t SPC

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.