System 99L forms over Hispaniola
The Atmospheric Infrared Sounder or AIRS instrument aboard Aqua provided temperature data on System 99L on Aug. 25 at 1:47 p.m. EDT (1747 UTC) . AIRS infrared data showed that the depression had some powerful thunderstorms with high cold cloud tops (as cold as -63F/-53C). NASA research has shown that storms with cloud top temperatures that cold can generate heavy rainfall.
A weak area of low pressure extending from eastern Cuba northward to the central Bahamas is producing disorganized shower and thunderstorm activity. The upper level winds from this low pressure system will be keeping System 99L from developing further for the next couple of days as it moves west-northwestward at about 10 mph. Conditions could become a little more favorable for development early next week when the system moves into the eastern Gulf of Mexico.
Regardless of development of the storm heavy rains with the potential to cause flash floods and mud slides are likely over Hispaniola today and over eastern and central Cuba through the weekend. Gusty winds and locally heavy rainfall are likely over portions of the Bahamas, and will likely spread into parts of South Florida and the Florida Keys over the weekend.