Note the last paragraph of the 11pm discussion & the statement about potential future development. This is what is called warm-core seclusion development, where an extratropical system acquires a warm-core by some means -- usually as the lower-level core becomes isolated (or, as in the title, secluded) from the outer, colder environment -- and usually results in explosive development.

The GFDL model in the cyclone phase space captures the storm very well currently and hints at this development, bringing the storm to a pressure below 960mb at it approaches Canada in a few days. For now, however, it shows a relatively weak, relatively shallow warm core -- i.e. weak warm core at low levels, cold(er) core at upper levels -- and this is a favorable scenario for such development as hinted by the NHC with the right forcing, as is expected down the line.

The global models have been predicting a significant system to move into the eastern U.S. and offshore later this week, providing the aforementioned forcing. Just this system alone -- perhaps the first significant front of the season -- would be noteworthy enough, but things could get really, really interesting off-shore later this week if things play out just right. I don't expect a nor'easter -- too far off-shore, among other things -- but some nice extratropical/quasi-subtropical development isn't out of the question by any means.

With the tropics essentially quiet otherwise, it's one to watch down the line.

Had the chance to drive through Matthew twice, once Friday and once today, going between here and Louisiana (even had the chance to meet another member of the board in person!). Driving in the rain is no fun, but that's about all it was -- a rain event. Parts of Louisiana really needed the rain, however, so it's not all bad -- just not all of it at once would've been better. It hardly had the look of a tropical system much of its life, taking on extratropical/subtropical features from its inception, but it'll go down in the books as the 13th storm of the year.