It looks like it could be a bumpy ride on the way to a nice weekend. A number of factors are coming together that could give us a large outbreak of severe weather on Friday. A warm front is ushering in a muggy air mass. On Friday evening, a powerful cold front will sweep through the region. That may provide the spark for severe thunderstorms.
One of the factors we look at when forecasting severe weather is how much “fuel” there will be in the atmosphere. That is measured as Convective Available Potential Energy, or “CAPE.” And there should be plenty of that on Friday evening.
What about tornadoes? Another factor we examine is called “EHI” or the Energy Helicity Index. It combines CAPE with helicity, or a twisting of the wind. As you can see, it looks like we have the potential for tornado formation late Friday afternoon, as well.
We think our biggest threat on Friday will be from strong, straight-line winds that could be in excess of 60 mph. However, large hail, dangerous lightning and isolated tornadoes are also a big concern.
Forecasting severe weather is not an exact science. Sometimes all the right ingredients are in place and nothing happens. However, we do believe that there is a big threat for severe weather late Friday afternoon and evening.