The trouble with Tomas
Posted by JAC on 11/3/2010, 6:14 am
The trouble Tomas has been having is that he has always been moving away from the UL anti-cyclone.

The anti-cyclone has either been situated to his left or rear.

What that means is that as he tracks away from the anti-cyclone he is moving into an atmosphere that has a decreasing tropopuse height.

What Tomas "sees" is a tilted tropopause height.

Ahead of him it is lower and behind him higher.

IMHO there is a reason for that.

As the season winds down, autumn sets in, the air gets cooler in the upper troposphere.

However, when deep convection fires, latent heating locally warms the upper troposphere.

At this time of year, there are higher temperature gradients in the upper troposphere than what would be seen say in the middle of summer.

These sharp temp gradients then are a major factor in how vorticies get stretched, compressed, and tilted as they move horizontally along the earth's surface.

This is the concept of Potential Vorticity (PV) "thinking".

In order for Thomas to intensify, the anti-cylone needs to get over the LLC.

This indicates that the tropopause has a local max height over the LLC.

That in turn would alllow the PV column to stretch vertically and become aligned.

Because of conservation of momentum, when a PV column streches it will spin faaster.

Right now Tomas is sitting in a wide area of moderate convective cells and stratiform precip.

This wide area may in fact be what is need to flatten out the UL temp gradient in the Carib and possibly get the anti-cyclone to move closer to what ever is left of the LLC.

Or a new LLC could in fact form somewhere else.








72
In this thread:
Again Convection decreasing and a weaking Tomas - hurricanephilip, 11/2/2010, 11:29 pm
< Return to the front page of the: message board | monthly archive this page is in
Post A Reply
This thread has been archived and can no longer receive replies.