Two Years ago Yesterday: Pilger Tornado Family

Two years ago today, one of the most infamous supercells in recent memory formed in one of the most incredible environments in recent memory. The Pilger, Nebraska supercell is one of the most productive and powerful supercells I’ve ever seen, as the storm produced four EF-4 tornadoes. FOUR. That is absolutely insane.

The tracks of the tornadoes that day. h/t NWS Omaha

The set up for this was really favorable, too. A long wave trough at the 500 mb level was centered across the northwestern coast of the US, with west-southwesterly flow across eastern Nebraska. Below that, the region was seeing southwesterly to southerly flow, advecting very warm and moist air into the region.

850 mb flow pushing a very moist and unstable environment into the region that day. h/t SPC

The 500mb flow across Nebraska and surrounding regions that day. h/t SPC

Surprisingly enough, atmospheric flow was actually fairly impressive, with relatively strong flow at all levels of the atmosphere from the surface and on up. Additionally, shortwaves were rotating through the eastern side of the longwave trough, moving northeastward.

A shortwave at 700 mb moving into the region. h/t SPC

By the afternoon, the surface, and the rest of the boundary layer, was incredibly moist and unstable. Dewpoints were in the low to mid 70s across the region, with temperatures in the upper 80s. This yielded one of the most impressive atmospheric soundings I have ever seen.

This is a bit complex, so I'll explain it briefly. The chart on the left is the plot of temperature, dewpoint and wind in the atmosphere above Omaha. This sounding shows an incredibly high amount of instability in the atmosphere. On the right, the chart is showing a 2-D plot of the magnitude and direction of the winds in the atmosphere. It is a visual representation of the wind shear in the atmosphere. There was A LOT of wind shear that day. h/t SPC — This is a bit complex, so I’ll explain it briefly. The chart on the left is the plot of temperature, dewpoint and wind in the atmosphere above Omaha. This sounding shows an incredibly high amount of instability in the atmosphere. On the right, the chart is showing a 2-D plot of the magnitude and direction of the winds in the atmosphere. It is a visual representation of the wind shear in the atmosphere. There was A LOT of wind shear that day. h/t SPC

A sounding just basically just a vertical look at temperature, wind and moisture in the atmosphere. It is collected by a balloon released twice daily, and at special times for big events. I have never seen a sounding with so much instability and wind shear all in one. It is wild, and was primed for a crazy supercell. All of this, in conjunction with shortwaves rotating through the region, sparked off a supercell that produced one of the most impressive families of tornadoes in recent memory.

This is a radar GIF showing the development of the mesocyclones on radar for the Pilger tornadoes and associated tornadoes. h/t US Tornadoes

The Storm Prediction Center had an excellent forecast for the day, and predicted the region of the tornadoes with excellent accuracy. Check out some of the wild videos of the Pilger tornado.

The Pilger supercell is circled in red. h/t SPC

This supercell was truly a marvel of the atmosphere, and is just fascinating. The set up, and eventual development of the Pilger tornado, is one of my favorite events to read about and learn about. This day was likely somber for the people who lost home and property, so keep them in your thoughts and prayers as they likely struggle with the memories of that day.