Nothing new in the tropics today

A tropical wave moving westward at 15-20 mph over the mid-Atlantic near 13N 47W, about 800 miles east of the Lesser Antilles Islands, continues to have the potential to develop into a tropical depression. The wave has a well defined surface circulation, and is currently under about 10-15 knots of wind shear, which is low enough to allow some slow development. However, there is quite a bit of dry air surrounding the storm, and thunderstorm activity is limited. It appears unlikely the wave will develop today. However, the long-range outlook for this wave is a little more favorable than it appeared yesterday. The upper level low that was expected to bring hostile wind shear over the wave later this week has weakened and is no longer expected to be a major influence. There is still expected to be 10-20 knots of wind shear along the path of the wave the remainder of the week, which is just low enough that a depression may be able to form. Dry air will continue to be a problem for the wave, and will likely keep development slow. The GFDL model predicts that the wave will develop by Thursday into a weak tropical storm, and move through the central Lesser Antilles Islands and into the Caribbean Sea. None of the other computer models develop the wave. I expect that the GFDL has the right idea, and this wave will develop into a tropical depression Wednesday or Thursday. The Hurricane Hunters are on call to investigate the wave on Wednesday at 2pm EDT.


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

Elsewhere in the tropics
A tropical wave moving through the Bahamas is under 20-30 knots of wind shear and is not expected to develop. An area of intense thunderstorms off the coast of North Carolina is also under high wind shear, and is not expected to develop. Long range models are showing the possibility of development off the Carolina coast this weekend, but anything developing here would likely be a threat only to Bermuda.

I'll be back this afternoon with an update, and an analysis of the NOAA updated seasonal hurricane forecast, due out later this morning.

Jeff Masters