All Weather News

Examining Tuesday’s “Moderate Risk” For Severe Storms

2 Jun 2014, 11:15 am

We saw an active weekend of severe storms, and plenty of flash flooding (even a major flash flood scenario in Minneapolis a few miles from my house!) – and now we’re watching our next system building in.  We’re talking about tomorrow’s storm threat.

Here is the current severe risk (as of 10:30am CT) for Tuesday:






See that “MDT” in the red-shaded area?  That’s a moderate risk for severe weather – which according to definition means about a 5-10% chance of severe weather occurring anywhere within that area.

So what is happening that is causing all of the weather?  What can we expect from it?  Let’s break it down…

We’ll start with the cause.  There is actually a wave of energy in the SW that will move east of the Rockies over the next 24 hours.  You can see a little cloud cover associated with it – but check out the “wave” of energy in this water vapor satellite image:



The dark you see is actually drier air, and that would be the “wave” of energy – while the white would be more relatively moist air.

A lot of rising motion happens ahead of waves of energy in the atmosphere – and sinking occurs behind it.

So now we know *why* storms will likely happen – we need to see what types of storms we can expect (we’re going with the assumption that storms are a sure thing in the red, moderate risk, zone).

Let’s take a look at one of my favorite model options – surface temperatures with surface winds.  Those are the variables I like to look at first (or a variable called “theta-e, which takes temperatures AND moisture into account).  Let’s look:






I highlighted a few of the more interesting wind zones Tuesday evening.  Eastern NE/southern IA/NE NE/NW MO all have winds at the surface going from southeast to northwest.

Those would all be areas of concern.  Especially with how quickly this low pressure system looks to move east.  Anywhere I’m seeing surface winds from the Southeast for tomorrow, combined with upper level winds from the South/Southwest, those are areas that a tornado would be possible (or even likely), should a strong supercell thunderstorm develop.

Notice also how those areas coincide with the moderate risk for severe storms you see in the beginning of the blog.  With the quick nature of that low, you could see storms develop throughout several states, all due to the same storm.

We’ll be watching closely here at WeatherNation!

WeatherNation Meteorologist Aaron Shaffer @ashafferWNTV

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