What is a mesoscale convective system?

Yahoo

13 hours ago

When the ingredients of moisture, an unstable atmosphere and a lifting mechanism combine, thunderstorms often form, but sometimes, several cells can join forces and turn into what is known as a mesoscale convective system, or what is often called an MCS.
Unlike a traditional thunderstorm that lasts for minutes or even an hour, once an MCS forms, it can take on a life of its own and last for several hours, spanning hundreds of miles of terrain.
The formation of an MCS usually happens during the warmer months when nighttime temperatures are sufficient to aid in thunderstorm development, without relying solely on daytime heating.
Once an MCS forms, it can essentially take on a life of its own, generating weather features that help it maintain strength and structure well after initial development.
In many cases, the low-level jet is responsible for the complex of thunderstorms persisting and maintaining its strength for hundreds of miles.
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The complex of thunderstorms often moves in a west-to-east or southwest-to-northeast motion and is directed by the jet stream or pressure patterns.
The primary threats from an MCS are gusty winds, heavy rainfall and plentiful cloud-to-ground lightning, but it can occasionally produce hail and isolated tornadoes.
If a tornado is associated with the system, it tends to occur along the leading edge of the thunderstorm activity; however, the primary concerns are usually flooding and damaging winds.
Wind gusts are often greater than hurricane-force, leading to downed trees, power lines and sometimes structural damage that can resemble a weak tornado.
National Weather Service offices often issue Severe Thunderstorm Warnings ahead of an MCS's impacts, during which people are encouraged to find safety in a sturdy shelter and stay away from windows.
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According to a long-term study, the most common regions to find MCS activity are the Mid-South, Gulf Coast, Central Plains and Midwest, especially during the May through August timeframe.
These weather systems are an important part of the climate, as some areas rely on MCSs for more than 50% of their annual rainfall.
There are several types of MCSs, with the most well-known being squall lines and derechos, but even tropical cyclones and lake-effect snow events can be classified as MCSs, depending on their formation and coverage.
To be classified as a derecho, a cluster of thunderstorms must produce a swath of straight-line wind damage covering at least 400 miles.
One of the most significant derecho events in U.S. history occurred across much of the Midwest during the summer of 2020.
During that event, winds gusted up to 140 mph, causing more than $7.5 billion in damage.Original article source: What is a mesoscale convective system?