.....Advertisement.....
.....Advertisement.....
Wednesday, September 09, 2009

Weather columnist Kevin Myatt: Offshore system has little hurricane potential

Kevin Myatt is The Roanoke Times' weather columnist.

kevin.myatt
@roanoke.com

981-3341


Weather with Kevin Myatt

Recent columns

Read the Weather Journal blog

#swvawx on Twitter

@KevinMyattWx

A low pressure system is spinning off the coast of the Carolinas and may meander just offshore the next few days.

Our natural tendency this time of year is to think it might become tropical. But that is unlikely with this low because of strong winds aloft that resist tropical development.

The low is baroclinic, which means its counterclockwise spin develops along a boundary of different air masses. The spin is focused in the middle to upper layers of the atmosphere, with any surface rotation developing because the spin is transferred downward through the atmosphere.

This is the way most low pressure systems occur, and it’s quite different from tropical lows, which form from the surface upward as the latent heat of ocean water — generally above 80 degrees — is released during evaporation.

Still, there are some cases when a baroclinic low in the middle to upper levels of the atmosphere will spin up a surface low that will become tropical in nature as it moves over warm waters with calm winds aloft.

That slight possibility is why the National Hurricane Center is monitoring the low off the Carolinas, though the official forecast maintains that tropical development is unlikely.

Weather Journal appears on Monday, Wednesday and Friday.

.....Advertisement.....