Usually when we talk about thunderstorms we think of warm and humid days, but every so often you can hear a boom of thunder on a downright chilly day in February. That’s what happened Tuesday afternoon; temperatures were still in the 30s when lightning developed and thunder started rumbling over North Alabama. How did a cold rainy day turn into a stormy day? The answer is elevated convection.
How Convection Contributes To Storms: Convection is a simple concept in itself: warm air rises and cool air sinks.
In a stable atmosphere warm air rises, then cools down and sinks, only to warm-up and start rising again. In an unstable atmosphere air warms with height, causing the air to continue rising. That’s the convection we talk about in relation to thunderstorms, and also why warmer days lend themselves to more thunderstorm activity.
Now, what about the cold days? Thunderstorms can develop on cold days due to elevated convection. Instead of convection starting at the surface, the convection starts higher up in the atmosphere.
First, there needs to be a layer of air above the surface that is warmer than the surface itself. If that air gets warmer with height or is forced upwards by some atmospheric feature, then BOOM! We’ve got convection! In Tuesday’s case, it was a pocket of ‘energy’ above the surface paired with a layer of warm air, which caused thunderstorm development to be possible.
For details on the ongoing rain and storm chances this week, check the daily forecast page here!