What happens when a mesoscale convective system collides with a cyclone?

Question

What happens when a mesoscale convective system collides with a cyclone?

Answer 1

UALog gave you the answer for a tropical cyclone. I don't know anything about those since I live at latitude 60 north. But for frontal lows in my region, it is not unusual at all to see a secondary low that forms on the front, to come and 'swallow' the primary low.

When that happens, their individual energy merges and an extremely strong convective depression can be expected.

That is what happened in 1979 when such a secondary low created hurricane force winds off the English Channel and sank or demasted several yachts in the Fasnet Race.

Answer 2

A tropical cyclone is a form of a mesoscale convective system (MCS) by definition.

(From the AMS glossary - MCS is an organized cluster of thunderstorms that is larger than individual thunderstorms, but smaller than synoptic-scale systems.  These systems include tropical cyclones.)

During its early stages of becoming organized and during the late decay phase of a tropical cyclone would most likely be the only time I would think a MCS (not related to the actual tropical cyclone) may have an outside chance of coming close to a well organized cyclone.  My best guess would be if the highly unlikely chance that they do meet, the cyclone would just absorb what was left of the MCS.  

Otherwise, any approaching MCS would likely weaken rapidly as it approaches the fair or mostly clear area surrounding the outer band of a mature tropical cyclone. This area of fair weather is associated with the strong subsidence.  This subsidence exists because of the strong convection associated with a mature tropical storm.  

Also, the low level inflow needed to keep a strong approaching MCS going wouldl not likely be able to compete with the surface inflow found in a nearby mature tropical cyclone.  At that stage, I really don't think they will ever meet.