Question on tropical severe weather events

[NickSeyour]

We typically look at things like CAPE , lapse rates and things of that nature when looking at a severe weather event. In the outer bands and somtimes eyewall of hurricanes , we find t-storms which can rotate and produce tornadoes and extra gusty winds. My question is whether or not DP, Temps , CAPE , EHI and things like that play as much , less or more of a role in the forecast for these outer band and eyewall storms. I know it sounds like a pretty obvious question but I'm a newbie

 

[Jeff Duda]

I don't know as much about tropical systems as some others on this forum do, but there is a distinction between continental and tropical convection. Tropical convection is usually associated with an atmosphere that has a higher tropopause, weaker winds, is warmer and more moist, and has a nearly constant, nearly moist-adiabatic lapse rate through most of the troposphere. Thus most of the convection that occurs in such an environment contain things different from those you'd find in continental (drier) convection, like frequent lightning and hail. I think the lack of lightning is due to the fact that you need some frozen precipitation particles to generate it, and in such warm and moist conditions representative of the tropics, you don't get that as much. Also, even though RH is pretty high throughout the troposphere, since lapse rates are so nearly moist adiabatic, it's hard to get very high CAPE, and the CAPE you get is generally very skinny and thus is more susceptible to entrainment killing/weakening an updraft. That's why you get rainy storms with little hail or lightning in the tropics compared to storms farther inland.

 

[GPhillips]

There's a paper that can be found here that has some nice summaries of previous research and the references for that research.

http://www.cimms.ou.edu/~schultz/papers/verboutetal05b.pdf

Most of the references can be searched for on the web.

 

[Paul Knightley]

For supercell tornadoes, the wind shear is much more important to updraught strength and organisation than the CAPE. The outer eye wall storms can sometimes have very good wind shear through them (e.g. the forward right hand side of a hurricane), as the low-level wind field can back markedly at landfall. Thus any storms forming in this area can be subject to strong directional shear, especially in the lowest 1km, and this can aid in tornado development.