ST. LOUIS – The stormy weather pattern slamming the St. Louis region since early July isn’t going anywhere just yet. So far, the month of July and the beginning of August have been the main culprits for a pattern known as a “jet stream.”

Jet streams are relatively narrow bands of strong wind in the upper levels of the atmosphere. According to the National Oceanic and Atmospheric Administration, jet streams form when warm air masses meet cold air masses. An unstable jet stream could also lead to severe heat waves or, like recently, excessive amounts of rain and storm threats.

“We’ve been kind of stuck in a pattern that’s more reminiscent of late May and June,” said Jayson Gosselin, a meteorologist with the National Weather Service in St. Louis. “The jet stream is not in Canada like it’s supposed to be, it’s more in our neck of the woods.”

The jet stream is the main driver of many recent storm systems. When it’s to the north, like it’s supposed to be in late summer, so are the storms. When it’s overhead, it brings storms through our region and provides the wind shear needed to fuel severe weather. 

Since July 1, meteorologists at the National Weather Service in St. Louis have issued 140 severe thunderstorm warnings and 11 tornado warnings, which is about three times the normal amount for this time of year.

This pattern continues for at least a few more days. It’s a tradeoff for the usual hot and dry weather the dog days of summer bring. 

“It looks like it will continue at least through this weekend, probably into early next week,” said Gosselin. “And after that, it looks like we may return to a hot and dry pattern. So maybe we’ll get a break from the storms, but we’ll get the heat.”

Severe weather is possible late Friday night into early Saturday and again late Sunday into early Monday. Click here to stay up-to-date on the upcoming storm system.