Pulse? Supercell? Not All Thunderstorms The Same

It's summertime and you drive from a blinding downpour on one side of your town to completely dry pavement and blue skies just a few miles away. What you might have just experienced is a pulse thunderstorm.

Here's a look at why one part of your neighborhood got soaked, while others stayed bone dry.

Big Picture

• What The Name Means: Pulse thunderstorms are also sometimes called pop-up thunderstorms, popcorn thunderstorms or air mass thunderstorms. Most of those names refer to how they develop in random spots with daytime heating in the summer, especially in the South.
• Miles Can Make A Difference: These storms make a great example of what you might see called isolated or scattered thunderstorms in your forecast when it's a summer day. The storm cells are often spaced out from each other, meaning parts of a city might be underneath their drenching rains, while locations in between them are dry, as shown in the general radar example below. In short, some thirsty lawns in a town might get a nice drink, while others miss out.
• Short Duration And Slow Moving: Pulse thunderstorms generally last less than an hour and move at a snail's pace since the upper-level winds pushing them around are weak. Sometimes they can billow up over a location and fall apart over nearly the exact same spot.

Deeper Dive

• They Can Produce Severe Weather: Occasionally these storms become strong to severe with strong wind gusts being the primary threat, but they also pack torrential downpours and frequent lightning. Flash flooding is sometimes produced by pulse thunderstorms that don't move much.
• Difficult To Forecast: It's tough to pinpoint down to the square mile where pulse thunderstorms will develop on a day. That's why isolated or scattered thunderstorms might appear in your daily forecast, but you see no rain at all at your home. The next day you might see the same exact same forecast and then pick up an inch of rain from a pulse storm at your house while a couple miles away it stays dry.
• About That Chance Of Rain: When you check your local forecast on weather.com or The Weather Channel app, you might notice there's a 30% chance of thunderstorms this afternoon. That simply means there's a 30% chance of rain happening at any point in the forecast area, according to the National Weather Service. So in the case of pulse thunderstorms, some locations in the forecast area might see that 30% chance of rain come true while others that dodged the storms are in the dry 70%. The percentage chance of rain does not tell anything about its duration or intensity.

(WATCH: Explaining Your Chance Of Rain)

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More To Know

• How They Form: These storms develop when the sun heats humid air and causes it to rise, cool and condense, allowing a cumulonimbus thunderstorm cloud to form. You can sometimes see these towering up in the sky some distance from where you are standing as the immediate area around you has blue skies and sunshine, as shown above.
• Why They Are Often Brief: They don't last long since there is usually little wind shear in the atmosphere where these storms form. That's because the lighter winds in the upper atmosphere cause the storm's downdraft (sinking air) to be located too close to the updraft (rising air). This results in the inflow of upward-rising air that fuels thunderstorms to get choked off by the rain and hail-laden downdraft, leading to the storm's abrupt demise.

Chris Dolce has been a senior digital meteorologist with weather.com for 15 years after beginning his career with The Weather Channel in the early 2000s.