African disturbance a threat to become the next tropical storm

A tropical wave over the mid-Atlantic near 12N 35W, about 700 miles southwest of the Cape Verdes Islands, has the potential to develop into a tropical depression in the next few days. The wave has a very large surface circulation. This circulation has an unusual elongated oval shape, oriented east-west, as one can see in satellite loops and the latest QuikSCAT wind pattern. Surface winds around the circulation were generally an unimpressive 15-20 mph in the 4am EDT QuikSCAT pass, and the wave has only limited thunderstorm activity. Wind shear is a favorable 5-10 knots, and sea surface temperatures are 27-28 C, plenty warm enough to support development. There is some African dust and dry air to the northwest, but not nearly as much as we saw with Chris last week. Conditions are much more favorable for development than we saw for Chris, and I expect we will see a tropical depression form by Tuesday night.

The computer models take the wave towards the west or west-northwest, bringing it to the Lesser Antilles Islands by Friday or Saturday. The GFDL models intensifies it to a Category 1 hurricane by Friday. Some of the other models are less impressed with the wave; the NOGAPS model doesn't develop it at all.


Figure 1. Preliminary model tracks for the mid-Atlantic tropical wave.

Chris looks pretty dead
Satellite imagery this morning shows very little is left of Tropical Depression Chris, just a few scattered thunderstorms near western Cuba stretching northward into the Gulf of Mexico. This activity is expected to move westward through the Gulf of Mexico and wind up near the Texas/Mexico border by Tuesday. Although wind shear is a relatively friendly 5-15 knots over the remains of Chris, there is so little left of it that redevelopment probably does not have time to occur before it moves ashore.

Figure 2. Preliminary model tracks for the remains of Chris.

Jeff Masters