One interesting discussion about Jelawat and the mysterious "boundary" off its eye.
I believe this "boundary" was actually a limiting streamline associated with a cyclonically curved, mesoscale jet streak. Such mesoscale jet streaks form in concert with horizontal gradients in latent heating (thermal wind arguments).
I "attached" the 18Z GFS model analysis at 250 mb on September 25, 2012. Couldn't get my software to print out values associated with color key, but 250-mb wind speeds clearly exceeded 100 knots around Jelawat (yes, wind speeds are expressed in knots). Quite unusual, in my opinion. So, in my view, this was a cyclonically curved, meso-beta jet streak induced by large horizontal gradients in latent heating probably in the middle to upper troposphere.
http://imageshack.us/photo/my-images/25 ... 25201.gif/
I've seen such mesoscale jet streaks form in concert with MCSs or MCCs here in the U.S.
Here's an example of a mesoscale jet streak associated with an MCS: