There are several reasons why hail rarely reaches the surface during a hurricane. You would think a hurricane would be so powerful that it would produce large hail. It is not so though. The freezing level is very high in a hurricane (often around 500 millibars (~5.8 kilometer altitude). In fact, a 500 millibar temperature above freezing is fairly rare but it occurs routinely in hurricanes. The enormous amount of latent heat of condensation and the warm saturated tropical air contribute to a very warm troposphere in the hurricane environment. The warm core structure of a hurricane will usually melt hail before it reaches the ground. There is also a shorter vertical growth region for hail since the freezing level is very high. The wind environment and lack of intense instability are also important. Very strong winds will blow the hail horizontally as it falls giving it more time to melt since it is not falling straight down. Also, the updraft in a hurricane is not as intense as that associated with a supercell thunderstorm. Hail requires a very strong updraft. While the updraft in a hurricane is strong, the energy is distributed over a large area and the updrafts are not of supercell intensity. |