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Breaking it Down with Brittney - Thunderstorm CAP

Breaking the CAP Explainer
Posted at 10:57 AM, Jun 28, 2021
and last updated 2021-06-28 11:57:46-04

BREAKING THE 'CAP': It can mean the difference between several strong storms firing up, or no storms at all.

The CAP is a layer of relatively warm stable air aloft, usually several thousand feet above the ground, which suppresses or delays the development of thunderstorms. As it separates warm, moist air below it and cooler, drier air above it.

Where the weather occurs in the troposphere, temperatures get colder with height. Not in this CAPPED layer though, it's the exact opposite. It's called an elevated mixed layer, or EML. Where the temperature only in this layer, begin to warm as you go further up in altitude.

Why does this matter? Well it acts like a lid. Much like how an inversion during the winter can trap clouds and smog near the surface, the cap suppresses rising motion in the atmosphere, making thunderstorm formation much more difficult, if not impossible. Whether or not you can "break" the cap can give forecasters headaches.

Meteorologist Brittney Merlot tells us ways the CAP can be removed or weakened and allow for explosive severe thunderstorm development to take place.

CAPPED vs. UNCAPPED