The National Weather Service’s Storm Prediction Center (SPC) is warning that Saturday could feature severe weather in portions of the United States. In their latest Convective Outlook for Saturday, the SPC says a significant severe weather outbreak is possible for portions of the middle Mississippi Valley on Saturday. The threats with the stronger storms include tornadoes, a few which may be significant, large to very large hail, and severe gusts.
A strong short-wave trough moving northeastward across the Plains and evolving into a compact closed low will drive the expected severe weather event. This low is forecast to be over the mid Missouri Valley during the afternoon and then continue moving northeastward to a position over Wisconsin by the end of the the day. At the surface, a low initially over Kansas is expected to move steadily northeastward in conjunction with the evolving upper low, occluding as it does. The low should be over Iowa by the late afternoon early evening hours. A warm front extending east from the evolving low will advance north into the Great Lakes while a cold front shifts out of the Plains and across the Mid Mississippi Valley. Due to this atmospheric set-up, a significant severe-weather event is expected across the northern Illinois area and portions of adjacent states. The greatest threat of severe weather will exist during the afternoon and early evening hours.
A variety of severe weather conditions are expected. Destructive wind gusts and large, damaging hail is possible in storm that form, especially over Illinois. This same area has an elevated risk of violent tornadoes which could not only be very strong, but wide too; they can also track for substantial distances. Frequent lightning and flash flooding from heavy rains is also possible, adding to the outdoor hazards.
With many sheltering-in-place due to the COVID-19 Pandemic, it’s important people anywhere severe weather is possible have a plan on what to do when severe weather strikes. While some structures like mobile homes may be suitable to shelter in for COVID-19, they may not be suitable for severe weather. Staying in a car or sheltering with others also adds additional hazards, and as such, people should use the quiet before the storms to plan out exactly what they’d do and where they’d go should Severe Thunderstorm or Tornado Watches and Warnings be issued.