Why do thunderstorms form in one part of the state but not the other?

Question

Today in virginia was a normal hot and humid day with some clouds in the early afternoon, both weather balloon sounding stations which are about 200 miles away read high CAPE and LI values but the northern VA one had higher ones than the southern VA one.

However thunderstorms blossomed all over the southern part of Virginia around 6pm while Northern VA stayed clear. Why? Is it a lifting mechanism or a trigger that caused storms to form in the south but not 200 miles north? The frontal boundary is still about 400 miles to the west. The storms were moving north however when they usually move east.

High CAPE values are a good predictor but what else can you use to predict storms, what about where they will form? I'm 20 and still learning as a hobby and I hope to go on a storm chase someday.

Answer 1

Could have been a number of things...

As you mentioned, there may have been a better lifting mechanism in southern VA..  (seabreeze, upper level divergence from jet activity, old outflow boundaries from previous day, etc.)

The shearing environment may have been slightly more favorable for development as well.

Stronger capping in the north is possible if you had slightly lower temperatures, morning overcast skies, slightly lower dewpoints, etc.

Answer 2

A thunderstorm is a type of storm that produces lightning and the sound of thunder. These storms often have heavy rain, as well.

The sound of thunder is caused when lightning quickly heats the air around it, expanding the air. As it cools, the air shrinks. This process of expanding and shrinking makes the sound that we know as thunder.

Thunderstorms usually last anywhere from 30 minutes to an hour. They typically happen in the summer or spring, when the air is warmer.

Look outside to see if a thunderstorm is coming. Look for dark clouds in the distance. You might even be able to see lightning flashes. You can also check your local TV news or radio stations to see if there are thunderstorm warnings in your county.

Answer 3

What I suspect is that the atmosphere over northern Virginia had a stronger "cap", i.e. a layer of warmer air off the surface that hindered thunderstorm formation.  Further south the cap was just weak enough that, in combination with some surface boundaries, thunderstorm development occurred.  Yes, CAPE values were high over both regions, but southern Virginia had just enough better setup for storms to realize that CAPE.