The National Weather Service is alerting area residents of the potential for hazardous weather entering the southwestern Illinois region late Monday night and into early Tuesday morning.

“Storms are going to be likely this evening and into the overnight hours,” according to meteorologists at the NWS St. Louis office. “There appears to be two different scenarios that could happen.”

A squall line will develop in west central Missouri this afternoon. One possibility is that the line will bring damaging winds with gusts greater than 60 miles per hour, along with the potential for isolated tornados. In the second scenario, supercell thunderstorms could develop ahead of the squall line, bringing an even greater risk of strong straight-line winds, damaging hail and tornados.

“Each scenario points to a significant weather event,” the NWS said.

The threat for southwestern Illinois, and Monroe County specifically, will peak after 1 a.m., although if storms develop ahead of the main squall line, they would hit earlier. Meteorologists said by the time the storms cross the Mississippi River into Illinois they will be in a “decaying stage,” with their intensity decreasing as they move.

Unlike the storms last week that produced more than 20 long-track tornados across the Midwest that stayed on the ground for miles, this storm’s potential is for isolated tornados embedded in the thunderstorms. These tornados are usually weak, typically EF-0 (65-85 mph) or EF-1 (86-110 mph), but can get as strong as EF-3 (136-165 mph).

Similar to last week, though, is the risk involved with storms that hit overnight, when people are sleeping and may not be aware of an impending threat. All residents are urged to keep a weather radio close by, tune into local news channels, and sign up for Code Red automated severe weather warnings through the county’s website, www.MonroeCountyIL.org, or by clicking here.