ST. LOUIS – The Memorial Day weekend starts with some severe weather threats in the St. Louis region.

Much of the region is under a severe thunderstorm watch through 9 p.m. Friday. A flash flood warning is also in effect for many Metro East counties through the 9 p.m. hour.

Storms will range from strong to severe, bringing large hail, damaging wind gusts, and a chance of some brief tornadoes.

Thunderstorm Watch

During a severe thunderstorm watch, atmospheric conditions are favorable for severe storms to develop. A watch becomes a warning when storms reach wind gusts of over 58 mph and/or if there is hail larger than a quarter-inch in diameter. This can pose imminent danger to life and property.

Most counties north of Jefferson and Franklin County in the St. Louis metro are part of Friday’s severe thunderstorm watch. If you’re in the area where a watch becomes a warning, seek shelter immediately.

Flash Flood Warning

When heavy, intense rain falls on an area in a short amount of time, flash flooding can occur. This often prompts authorities to use the phrase “Turn Around. Don’t Drown.” Drivers should turn around and use an alternative route rather than risk driving through high waters with safety in mind.

Friday’s flash flood warning includes Macoupin, Jersey and Greene counties in Illinois. Some viewers have also informed of flash flooding Friday near Litchfield, Illinois after heavy rains.

Tornado chances

The National Weather Service has not issued a tornado watch for the St. Louis region through Friday evening, for the moment. There was one warning earlier Friday near Montgomery County, Illinois.

During a tornado watch, atmospheric conditions are favorable for a tornado to develop, but a tornado has not yet been sighted or indicated by weather radar.

When a tornado warning is issued, a tornado has been sighted or indicated by weather radar and there is imminent danger to life and property. If you’re in the area of a tornado warning, seek shelter immediately.

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