Sean has apparently had no problem transitioning from a sub-tropical structure to a tropical storm. He is now relying on warm moist air from sea surface evaporation to fuel his circulation. The NHC is forecasting Sean to remain a tropical storm for 2 more days, as he gets swept up to the north. Once he gets above 30N, the ocean surface temperature will no longer be able to support the growth of a tropical cyclone, and Sean will begin to die. He will have a very difficult time gaining much more strength before then, although the NHC is giving Sean good odds of topping out at a 65 mph tropical storm on Thursday. He is going against the grain right now, once he turns to the north, upper level winds will become more favorable, and he will also be moving away from the bulk of dry air. Sean may bring Bermuda some moderate effects on Thursday night.
(Tropical Storm Sean)
The Mediterannean Storm that the US Navy has identified as Invest 99L is about to make landfall in the French Riviera. It will likely bring tropical storm force sustained winds and heavy rainfall to that area.