We are tracking a very unusual July severe weather pattern that could trigger damaging storm complexes across the Mid-Atlantic and East Coast late next week.
Before that arrives, life-threatening flash flooding will continue hammering the Ohio and Mississippi Valleys, while a massive heat dome brings record-breaking temperatures to the West.
We break down the timing for every region, plus where you can find absolutely perfect weather this weekend.
About Mesoscale Convective Systems (MCS)
A mesoscale convective system (MCS) is an organized complex of thunderstorms that is larger than an individual storm cell but smaller than a synoptic-scale extratropical cyclone.
These systems typically persist for several hours or more and can reach a horizontal extent of over 100 kilometers. MCSs are characterized by regions of both intense convective precipitation and extensive mid-to-upper level stratiform rain.
They can manifest in various shapes, including linear squall lines or circular clusters, and often develop during the warm season over land in the late afternoon and evening hours.
These systems are capable of producing significant weather hazards, such as heavy rainfall, damaging wind gusts, and prolific lightning.
In some cases, an MCS can develop a mesoscale convective vortex (MCV), a low-pressure center that pulls winds into a circling pattern.
An MCV can persist for up to 12 hours after the parent thunderstorm cluster has dissipated, potentially triggering new convection later.
Particularly intense and long-lived linear systems that produce widespread wind damage are known as derechos, while exceptionally large, quasi-circular, and long-lasting MCSs are classified as mesoscale convective complexes (MCCs).
Urbanization has been shown to influence the behavior of these storms, though the effects vary by storm type.
Research indicates that while synoptic-scale frontal storms may weaken over urban areas due to thermal and roughness effects, local-scale isolated storms often increase in frequency over cities, particularly at night.
The development of MCSs is often supported by environmental factors such as moisture, atmospheric instability, and lifting mechanisms, sometimes utilizing features like the Intertropical Convergence Zone (ITCZ) or monsoon troughs in the tropics as a focus for development.
