UPDATE (9:30 PM EDT): The system is now TD-3

Over the last few hours, the thunderstorm activity associated with Invest 99L has become more organized. Convection is now over the center of low pressure (Figure 1). Also, the latest QuikSCAT pass at 7:30 PM EDT shows that there is finally a closed center of circulation and winds close to 35 mph (Figure 2). At the 11PM advisory, I fully expect that NHC will declare this system to be Tropical Depression Three. Stay tuned to the StormTrack for more.

Figure 1. Infrared satellite image of Invest 99L. The reds in the center of the storm show the most intense thunderstorms, a sign that 99L is strengthening.

Figure 2. QuikSCAT satellite imagery of Invest 99L. The red wind barb to the north of the center of circulation is a 30 kt (35 mph) observation.