Cold Air Funnels

The region of the United States from North Dakota eastward to Michigan probably has more incidences of cold air funnels than anywhere else in the country.  Cold air funnels are condensation funnels that form in and around weak convective showers.  Because the updrafts within these showers are relatively weak compared to that found in supercell thunderstorms, there is less energy available for rotation.  Cold air funnels usually do not reach the ground.  If they do, they usually do not do much damage as their wind is usually more like what is found in a dust devil than a tornado.  However, there can be hybrid situations in which a cold air funnel does become strong when its parent shower grows stronger.  The term, cold air funnel, comes from the fact that these weak funnel clouds often form when the air is cooler and more stable.  However, temperature, alone, is not the determining factor between a weak funnel cloud and a tornado.  It is the strength of the updraft that is the critical aspect.   Meteorologist John Wheeler