Where is the Coldest and Stormiest Weather in a Mid Latitude Cyclone?

June 15, 2023

A mid latitude cyclone feeds on the temperature and density contrast between warm Gulf of Mexico air and cold, polar occluded Atlantic air. This naturally large temperature gradient creates fertile breeding grounds for mid-latitude cyclones. The animation below shows the progression of one such storm, from a "baby" 1009 millibar low along a stationary front in Texas to a fierce 987-millibar occluding mid-Atlantic low, in a little more than three days.

The location of a mid-latitude cyclone's low pressure center is critical to its weather impacts. Severe thunderstorms occur to the east of a surface low, where warmer air is found, and wintry precipitation occurs north and west of a low, where cold air is present. The location of a surface low within the jet stream (trough or ridge) is also critical to its movement. A cyclone track that moves over a jet-stream trough is associated with a Low at your location, with local bad weather (clouds, rain and snow), while a cyclone track that tracks over a ridge is associated with a High at your location, with good weather (light winds from the north-west through south-east).

The speed at which a cyclone moves is determined by the direction in which the winds in its core are blowing. The winds rotate counterclockwise around a cyclone. With time, a cyclone develops a warm front, then a cold front. As the cyclone moves west, the atmospheric temperature gradient is reduced due to the displacement of warmer air poleward and colder air equatorward. This helps the atmosphere strive for balance by reducing hemispheric temperature differences. The cyclone eventually weakens and dies, but it has done its job.


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