Tropical weather analysis - June 22, 2010

Began writing approximately 8:26 PM eastern

Invest 93L continues to thrive, and is generating heavy thunderstorms over portions of Puerto Rico, Hispaniola, Jamaica, and eastern Cuba. These heavy rains may cause some flash flooding and mudslides across earthquake-ravaged Haiti over the next day or two, as I would imagine that 3-6 inches of rain is likely to fall there, with locally higher amounts, particularly across mountainous regions. Based upon shortwave infrared satellite loops, it appears that the center is located near 16N 75W. Deep convection is currently minimal near the estimated center position, but appears to be acquiring banding features, with the thunderstorms attempting to wrap cyclonically into the broad but gradually organizing surface center.

93L is currently centered almost completely underneath an upper-level anticyclone. This, along with strong vertical shear from the TUTT to the north, should assist in ventilation of the system. However, given that divergence convergence are naturally stronger during persistent convection, ala the aforementioned thunderstorm complex to the east of 93L's estimated center, it is my prediction that 93L will struggle a little bit this evening, as that thunderstorm complex robs it of most of its energy. Think of it like a developing tropical cyclone in the ITCZ -- often times they compete with one another, and ultimately, one of them wins out. So who will win out in this particular situation?

I would say 93L, given that an anticyclone is centered above the system. However, given the aforementioned influence, along with surface and buoy observations indicating a lack of a closed surface circulation, I am not expecting any significant development of 93L tonight, and even into this morning. By tomorrow afternoon, however, it should begin to organize. A reconnaissance flight is scheduled for 93L tomorrow, and they will no doubt be able to provide us with better data than what we currently have, should the mission actually transpire.

93L is currently moving W at 5-10 kt, based on satellite animations and low- to mid-level steering analysis from CIMSS. I expect a general WNW motion, with the occasional jog to the W at around 5-10 kt throughout the next several days, and I do expect that 93L will eventually find its way into the Gulf of Mexico. The models are divided as to whether or not 93L will eventually develop. The CMC, ECMWF, GFDL, and HWRF all foresee the system developing, and all of them save the HWRF bring it to hurricane status while located across the southern Gulf of Mexico. The NOGAPS, GFS, and UKMET models, on the other hand, do not develop 93L (though the GFS is showing the formation of a low pressure area on the verge of becoming a tropical depression, more than it has been doing for the last several days).

However, they all agree on one thing: a shortwave trough in the westerlies will begin eroding the subtropical ridge, the western extent of which is currently located east-west across a large portion of the eastern and northern Gulf of Mexico, by around 72 hours. 93L should be either be approaching landfall in the Yucatan Peninsula at this time. the solution provided by the NOGAPS, GFS, and UKMET, or in the Yucatan Channel between the Yucatan Peninsula and western Cuba. The former is more likely in the event of a weaker system following the low-level flow, while the latter is more likely with a vertically deep system following the mid-level flow.