St. Louis forecast: Severe storms possible this weekend

ST. LOUIS — Sunday’s severe weather threat is still on track to impact much of the bi-state. The cold front raced through the plains and arrived early this morning. 

The colder air behind this front is important. Not only will it clear our severe weather threat out really quickly on Sunday afternoon, but the presence of cold air aloft will really aid in the production of some very large hail.

Storms developed to our west overnight. Most storms stayed under the severe storm threat. If clouds from these storms stick around, they may mitigate some of the severe threat for us on Sunday, primarily on the Missouri side.

But here’s the position of this cold front at 9 AM Sunday. It’s already moved halfway through the state at this point. Because of that, certain areas are limited to less of a severe weather threat, as they may not recover and become unstable in time for that to arrive.

That’s why the risk level varies so much from west to east. It’s more of a matter of timing versus the actual ingredients in place. There will be plenty of time to recover and get warm and sunny by this point.

Let’s prepare for the potential for severe weather as early as 11 AM. By noon, a few storms may start to develop. This will be conditionally based on how cloudy or rainy it still is from the early morning storms.

By early afternoon, more storms start to develop. Notice how they are by themselves? These generally have some sort of rotation and are more prone to hail production. That’s why it’s important for them to be watched in this regard as very large hail is possible.

At this point, storms are heading into a heated afternoon, and therefore a more favorable environment. That’s why areas in the Metro East are more likely to see stronger storms, due to the timing of the front.

As mentioned before, the comparison between this storm and the last is the fact that the wind field isn’t quite as strong. 60-70 mph wind gusts still look possible in the higher-end severe storms that may develop. We could also see up to tennis-ball-sized hail as well. 

To put this in perspective from the last storm, there doesn’t seem to be some large tornado outbreak that warrants a tornado count over 10 in the region. But that doesn’t mean tornadoes aren’t possible, but we are monitoring less of a widespread outbreak. Hail is a bigger threat this time around, with an upside of tennis ball sized.  

While a few tornadoes are possible also, our team is not expecting a widespread outbreak. Flash flooding isn’t a threat at this particular time, either. This is just an early call, but follow along here for updates to the forecast as we continue to fine-tune the threats and timing.

5 On Your Side meteorologists will use Weather Impact Alerts to let you know when impactful or dangerous weather is expected as soon as there is confidence in disruptive weather happening in our area.

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