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Why are Storms More Dangerous in Spring?

5 Apr 2017, 5:16 am

During the month of April the threat of severe weather ramps up across the southern U.S.

In fact the months of April, May, and June are typically the 3 most active months of severe weather for the U.S.

A Changing Atmosphere

You may notice it as you step out the door, April is a month of change. No longer do we have those cold winter nights and an increased sun angle means we see daytime highs climb to levels in which shorts become an acceptable choice of attire. But those warmer temperatures do wonders when it comes to destabilizing the atmosphere.

Warmer air holds more moisture.
Think of it this way, since a dew point can never be higher than the temperature– when the temperature rises, so can the dew points.

The increased moisture in the atmosphere makes the individual particles more buoyant, or lighter. Because warm, moist air is much lighter than cold, dry air. So when you add a lifting mechanism, those lighter particles want to be above the heavier ones and their rising fuels thunderstorms!

The Springtime Jet Stream

As we get into the summer months, the jet stream levels out into a more zonal flow. Almost west to east, it helps keep our weather rather uniform.
However, during the months of spring, the jet stream still has very pronounced ridges and troughs. This not only helps deliver those potent cold fronts, but also adds an upper-atmospheric component to the development of storms.

  1. Ridges and Troughs.
    This roller coaster-like pronunciation both helps to bring in warm, wet air from the south and Gulf of Mexico and cold dry air from the north. Meteorologists often talk about the “clash of the air masses” and the jet stream is a big reason those air masses move into play. And as we discussed earlier, the cold, dry air overtaking the warm, moist air means the lighter particles want to rise– fueling the strong storms.

  1. Evacuation.
    Strong overhead winds mean those rising particles we keep talking about get blown away from the original point they rose. This allows others to rise in their place, continuing to add fuel to the powerful thunderstorm.
  2. Shear.
    The powerful jet stream adds an element of wind shear to the atmosphere.  The changing of wind speed and direction with height adds a spin that helps supercell thunderstorms rotate. A major part of tornadic development.

Well That was Simple

Actually, it’s much more complicated than that!
But for the sake of simplicity and an easy read– we stuck to the basics.
There is always more to learn and more questions to be answered, so as usual– any questions, please feel free to ask on social media!

Tornado Caught on Security Camera

WATCH how the Virginia Beach EF-2 tornado from March 31st impacts this house! Rain and debris quickly create blinding conditions on this security

Posted by WeatherNation on Wednesday, April 5, 2017

For WeatherNation — Meteorologist Jeremy LaGoo

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