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Analyzing Late-Week Severe Threat

26 Mar 2014, 11:15 am

It’s that time of the season, severe weather season, when we start seeing more and more days of organized severe weather threats.

Thursday & Friday are no different.

It reminds me of my storm chasing days while living/working in Iowa – this shot below was from a chase in Missouri, and I’d imagine scenes like this will show up all over the place in the next 48 hours.

 

 

What’s Happening Thursday & Friday?

 

This set-up for Thursday and Friday is interesting, because we end up with two different regions of low pressure that cause the individual severe weather threats.

Thursday’s is an area of low pressure coming off of the Rockies (the northern Rockies) and moving into the Midwest and Central Plains with a cold front sagging south.

 

Thursday Severe Weather Threat: As Of 10:45AM CDT

 

Forming along that cold front would be a secondary circulation that gives you your severe weather threat for Friday (aside from any lingering storms along the cold front).

 

Friday Severe Weather Threat: As Of 10:45AM CDT

 

Then, thankfully, things calm down a bit.

 

 

Breaking Down Thursday

 

There’s a lot going on with this particular storm system, but we’ll keep it to the basics of severe weather: you need a storm, that storm needs energy, and it needs shifts in wind with height to keep itself going.

Looking at Thursday, it becomes an interesting set-up with a low pressure center coming off of the Rockies.

 

 

Notice those wind arrows on the map.  Those are surface winds, and you can see how they converge together right along the cold front.  When you have converging winds, you get rising motion – and that is what will likely cause any strong to severe thunderstorms.

 

Thursday Forecasted Storm Energy

 

The more broad view shows that narrow finger of “storm energy” moving north – getting sucked into the low pressure center in the area.  It’s interesting to see, and shows that there will likely be enough energy for some strong storms…

 

Breaking Down Friday

 

Friday intrigues me a bit more than Thursday, thinking as a chaser, that is.

On the tail end of the cold front/cold air boundary the models are starting to show a secondary region of low pressure forming.  That’s not uncommon, but given how humid the atmosphere will be behind the previous day’s showers, even a weaker area of low pressure will have plenty of moisture to work with.

Here is what the models are showing for Friday afternoon:

 

 

While this is just one exact time period – the area to watch will be immediately southeast of the center of low pressure.  See over southern Arkansas in that still image above?  Those are surface winds that come from the south, and a mile or so up in the atmosphere you end up with winds more from the West or the Southwest.  That gives you your twisting motion with height.

What else is needed?  Storm energy.

 

 

Look at that image above.  This is only one computer model’s view – but there appears to be *plenty* of storm energy.

The end result?  We’re seeing two fairly robust days of severe weather as a likely scenario across the nation.

Stay tuned to WeatherNation!

WeatherNation Meteorologist Aaron Shaffer @ashafferWNTV

5 responses to “Analyzing Late-Week Severe Threat

  1. Mom-in-law lives in Lubbock, TX and talks about how great WeatherNation is compared to others. Just logged on and she’s right. I like the maps, especially surface winds.

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