Extreme hail, winds, more possible Thursday and Friday

ST. LOUIS – Welcome to what is likely to be the warmest and most humid day so far this year! Highs today are likely to reach close to or above 90 in many spots.

That kind of heat and humidity will make the low level atmosphere very unstable as a weak cold front arrives from the west Thursday evening.

There is a level 2 (out of 5) risk of isolated, very fast moving, severe storm or two late in the afternoon and evening for Illinois and southeast Missouri. The risk will be confined to the 5 p.m. to 8 p.m. window of time. Isolated damaging wind, hail and tornado threat will exist.

The initial development may start near St. Louis, but it will not mature until it crosses into Illinois. 

After Thursday evening, our attention quickly turns to Friday afternoon and early evening.

A level 3 (out of 5) risk for severe storms exist then over the southeast half of the viewing area, including Metro St. Louis. While there are still quite a few uncertainties about the timing and evolution of the severe threat Friday, the overall pattern is more supportive of severe storms Friday than today. 

We could have a few strong storms in the viewing area as early as noon. Strong to severe storms are possible anytime from noon through 7 p.m.—that’s a pretty broad window of time. 

The threat for severe storms will be greatest southeast of Interstate 44 in Missouri and south of Interstate 70 from metro St. Louis east into Illinois. 

All severe hazards are possible, but I am especially concerned about extremely large hail in the strongest storms which could reach up to baseball-sized, if not a little larger. There will also be a risk of isolated tornadoes and damaging winds.

The bottom line for Friday is to be weather aware during the afternoon as some of these storms could impact athletic events, school dismissal, etc.

And not to be left out, mark your calendar for next Tuesday. Long range charts point to a potentially very active day for severe weather across the Bi-state area. But that is still five days away. I won’t be diving deep into that one for a few more days.