GOLDEN VALLEY, Minn. - In the summertime, we sometimes get popup thunderstorms. I recently had a viewer ask:
Hey Jeff what causes the scattered thunderstorms like we are seeing? I understand fronts often times bring weather with them but there doesn't seem to be any particular pattern to the thunderstorms all over the radar we are seeing.
Thanks for your question, Chris. These are called air-mass thunderstorms. To create them we need three basic ingredients, lift, instability and moisture. These storms are rarely severe and are created by instability in the atmosphere. While these are common in tropical climates like Florida, we don't see them as often here.
This is how they form, early in the day we will have a field of cumulus clouds, after a few hours by the early afternoon, a few clouds will start to get much taller. This is stage one, or the towering cumulus stage. This is your clue that we might see rain later in the day. The mature stage of an air-mass thunderstorm comes when we have rain falling and the thunderstorm has grown to more than 40,000 feet in height. Since air-mass thunderstorms develop straight up, they tend to eventually rain on their updraft, where the warm and humid air is feeding the storm. This causes them to self-destruct and dissipate which is stage three.
When air-mass thunderstorms popup, expect a period of heavy rain, but like yesterday we can also see landspouts, hail and even high winds.