From James Spann
Potential Tropical Cyclone 18
PTC 18: Invest 97L is now Potential Tropical Cyclone 18.
The environmental conditions appear conducive for strengthening during the next few days, and it seems likely that the system will become a tropical storm (the name will be Rafael) before it reaches Jamaica and a hurricane before it reaches Cuba. However, later in the week, southwesterly vertical wind shear and intrusions of dry air should end the strengthening process and likely induce weakening once the system reaches the Gulf of Mexico.
The hurricane regional models are very aggressive, however, their intensity predictions appear overdone, at least in the short term. Most global models show the system becoming a weak, broad low as it nears the U.S. coast, mostly a rain-maker.
It remains to be seen where the most beneficial rain will fall from this system as the track forecast in the Gulf remains rather uncertain. Once the system reaches the Gulf of Mexico by the middle of the week, the model solutions diverge due to differences in the predicted steering patterns and vertical depth of the system by that time.
We will have better clarity over the next few days; if parts of the Deep South are to see meaningful rain from this feature, it will be Friday-Saturday time frame.
