Have you ever watched a promising thunderstorm barrel toward you, only to see it fall apart or shift course at the last second? It can be frustrating to expect the cooling relief of a nice deluge—only to be left high and dry as you watch the dark clouds fade away on the horizon.
It’s common to describe this phenomenon as a “bubble,” a perceived forcefield hovering over your town that seems to deflect storms when you want them the most. There’s even an XKCD comic about it. Of course, those mythical deflectors don’t exist, but why do storms seem to consistently hit certain areas, while often skipping nearby towns?
Some local features, like large, cool bodies of water or tall mountains, really can affect how thunderstorms behave. But for the most part, a storm suddenly missing one location is mostly the result of how these bubbling masses of air and moisture evolve throughout their short lifecycle.
There are three common types of thunderstorms—single-cell, multicell (think squall lines), and supercells. The latter two categories are commonly associated with organized severe weather outbreaks. By far the most common type of thunderstorm around the world is a single-cell. This is a small, localized burst of convection often called a pop-up, popcorn, or garden-variety thunderstorm.
If there isn’t a focus point for thunderstorms to develop—something like a cold front or a sea breeze—the exact location where one of these warm weather torrents develops is usually pretty random. A storm will pop up, produce lots of lightning and heavy rain for a little while, and then start to dissipate. The cold air rushing away from the decaying storm will serve as a focus for more thunderstorms to develop nearby. Whether or not you get hit by an approaching thunderstorm depends on how healthy it is, and if any other storms form in its wake. In other words, if a storm falls apart a block away from you, it’s usually a stroke of atmospheric luck.
If you average out precipitation trends over a long period of time, the data show that rainfall is pretty evenly distributed between neighboring communities. One storm could miss you and hit the town next door, while the storm that hits you missed your neighbors down the street. It balances out with time.
However, there are some cases where certain towns benefit from their surroundings when a thunderstorm is on its way. Thunderstorms can start to weaken as they approach more stable air near cool bodies of water like the Atlantic Ocean or the Great Lakes. There is also some truth that mountains are less conducive to storms, as the rough terrain and cooler temperatures can disrupt the updraft and temporarily weaken storms as they traverse the terrain. That certainly isn’t always the case, though—there are plenty of rocking storms along the coast and in the mountains every season.
So for the most part, if a thunderstorm looks like it’s coming straight for you and then disappears into thin air, it has less to do with where you live and more to do with the fragile, fluid structure of these magnificent natural formations.