Environmental thermodynamics can mean a lot of things, but here, it's likely heat content (not a whole lot in the ocean, but improving with time) and midlevel moisture (which the storm has been embedded in since the African coast).

Really, I think the bigger question now becomes: will this storm hit South America? Unless the storm makes a quick jog to the north in a hurry, it might very well do so. Unfortunately, the Univ. of Wisconsin steering layer wind products are currently unavailable, but the storm has been moving (or rebuilding) further to the WSW for the past 6-12hr. It's going to be a close call as to whether or not it hits South America -- and if it does, it may not recover (or may take until the western Caribbean to do so, if it emerges off of land). Expect advisories for Trinidad to match those in Tobago at 11p with potentially advisories posted for the north coast of South America at that time as well.

Aside: T numbers on 99L are 1.0 now from SSD. Not anything to write home about, but it continues to become better organized. If this trend continues, it's got better than even odds of becoming TD 6 in the next day or two.