Fall Severe Weather Threat

Severe Threat For This Weekend

A major severe weather threat is developing for the Midwest for the upcoming weekend. A potent weather system will be moving out of the Plains and toward the Great Lakes Friday into Sunday.  This system has quite a bit of energy as can be common in the fall as the seasons change. Storms with strong winds, large hail and tornadoes will be possible for areas such as Missouri, Iowa, Minnesota and northern Illinois.  There is potential for some tornadoes to be significant if all parameters come together as they look like they are going to do on Saturday.  This threat highlights the fact that October and November into the beginning of December can be stormy again as the seasons change from the warmer months back to the cooler months of winter. Much like in the spring, the jet stream becomes very active and so do cold fronts. To get significant severe weather, you need three things to come together:  

1. Instability in the form of warmth and moisture
2. A trigger to lift the warm moist air upward – such as a cold or warm front
3. A vigorous jet stream to help energize the storms and provide shear needed for storms to rotate.

These three factors happen most often in the spring giving us our most substantial severe weather threat in the months of March April and May in the southeastern part of the country. But our secondary severe weather season in the fall can also provide significant severe weather events as well.  In recent years, November tornado outbreaks in occurred in 2002 and 2005. Even in this relatively new month of October, three tornadoes have already touched down in Middle Tennessee.   On Christmas Eve morning of 1988, an  F4 tornado ripped through Williamson County Tennessee across the current location of the Cool Springs mall. One person was killed when his house was destroyed near the current intersection of Mack Hatcher Parkway and Franklin Road. Because the jet stream can be very strong this time of year, the tornadoes can be significant.  

Let this threat this weekend to our Northwest be a reminder to have your tornado action plan in place including:

1.  A source of warnings such as a weather radio or a smartphone warning app (such as MyWarn or iMap Weather Radio)
2.  Know the safest place in your home – generally on the lowest floor in a central part of the home away from windows.  Small closets or bathrooms are good – especially under a set of stairs.
3.  When the warnings come out, take action!  Many of the tornadoes in the fall season happen after dark.  Don’t look for it out your window – seek safety immediately.

Soon, weather radios are going to become very user friendly as they will be equipped with a GPS feature soon that will require no programming at all.  More on that soon…


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