But what about the celebration in Jamaica for Usain Bolt??
Disturbance 94L approaching the Lesser Antilles
Heavy thunderstorms associated with a tropical wave (94L) near 11N, 54W, about 500 miles east of the Lesser Antilles Islands, have grown more concentrated in recent hours. This disturbance could be trouble, and bears careful scrutiny. This morning's QuikSCAT pass mostly missed 94L, but did show a pronounced wind shift at the western edge of the disturbance. Visible satellite loops show some evidence of rotation and increase in heavy thunderstorms, but I'm also seeing surface outflow boundaries to the southeast, indicating that dry is getting sucked into the thunderstorms and creating downdrafts that rob the disturbance of energy. Wind shear has fallen to a modest 10 knots over 94L, and the dry air surrounding it has been steadily moistening. Wind shear is expected to drop to a low 5 knots and remain low for the next four days, and NHC is giving this system a medium (20%-50% chance) of developing into a tropical depression by Sunday afternoon. I would put the odds at 40%-70%. Three of our reliable computer models develop the storm. It's easy to see why--the wind shear forecast for the Caribbean calls for very low values of wind shear below 5 knots for most of the coming week (Figure 2). The GFDL calls for 94L to develop into a Category 2 hurricane that threatens Jamaica on Tuesday. The HWRF doesn't develop 94L at all, and the ECMWF and NOGAPS models call for 94L to eventually develop late next week after it moves north of Hispaniola, into the Bahama Islands. All of these models used the wrong starting position of 94L, since the storm re-formed 150 miles to the east of where the models were expecting it to be. Thus, we can put little faith in the details of forecast track of 94L predicted by the models. A track through the Caribbean towards Jamaica currently appears to be the highest probability track to me. Residents of the Lesser Antilles can expect heavy rain and 40 mph wind gusts from 94L when it blows through Saturday and Sunday. Residents of the Dominican Republic, Haiti, and Jamaica should keep a careful eye on this potentially dangerous disturbance.
(Dr. Jeff Masters, 08/22/08 5:22PM EDT) |
