Thursday, July 11, 2013

Chantal's Demise

What was Tropical Storm Chantal at this time yesterday is no longer defined as a tropical cyclone, having lost its complete center of circulation and transitioning into a strong trough.  Chantal's "fizzling" as a tropical cyclone was due to a couple of factors.  First, westerly upper level winds thanks to its track to the north of upper level high pressure in the Southwest Caribbean Sea and to the south of an upper level trough in the Atlantic.  While those winds weren't terribly strong, the combination of them and a rapid track into those upper level winds provided a hostile environment.

It really didn't help that Chantal was moving at nearly 30 mph into those upper level winds.  The rapid surface flow exacerbated the modest upper level winds and made the environment unfavorable for strengthening thanks to the strong easterly flow in the lower atmosphere.

Second, dry air in the Caribbean didn't allow for additional thunderstorm development to take place as the weakening of thunderstorms with Chantal's shear problem. This added fuel to the fire of the storm being unable to maintain a distinct low level circulation across the Caribbean.

There is still pockets of thunderstorm activity with the trough that's leftover from Chantal, with the bulk of thunderstorm activity now north of Hispaniola and not near the old low level trough axis.  This wave/trough will track west-northwest towards Florida and through the Florida Straits over the next 48 hours.  Some of this moisture will get sucked into the Southeastern United States but it appears now that the threat of this system being much more than a moisture inducer and rainfall exacerbation for the already soaked Southeast is rather minimal.