We are heading into an active weather pattern that’s going to bring multiple rounds of rain and thunderstorms to the St. Louis region (and much of the Midwest) this week. The first round will come through tonight into Monday morning and a few more rounds will be possible through at least Tuesday night.
Southwest flow will be in control and that will bring a ton of moisture to the area – straight from the Gulf of Mexico. This means there will be plenty of moisture in the atmosphere to fuel these rounds of precipitation. It won’t rain all day, every day, but it will be soggy at times.
Southwesterly flow will also usher in warm air for Monday and Tuesday, ahead of a cold front, where temperatures will likely reach the low to mid 70°s. Right now, it looks like the cold front will move through late in the day Tuesday which will be one of the soggier time frames as another round of rain and thunderstorms move through.
Rainfall totals through Tuesday night could exceed 3″ in some places.
Behind the cold front, late Tuesday night into Wednesday morning, colder air will move into the region. There is a chance (not a great chance at this point…lots of uncertainty remains) that rain may transition to a wintry mix on the back end of this system. Freezing rain and sleet would be possible if this happens, but this is very dependent on the timing of when the cold air arrives and how much precipitation is left.