TD 15? And, Katrina: an unnatural disaster

Two disturbances to watch off of the coast of Florida
The important threat in the tropics today is a large area of disturbed weather extending from Miami eastward over the Bahama Islands. A small circulation center, visible on winds from the QuikSCAT satellite, has developed in association with this disturbance, about 50 miles east of Ft. Lauderdale, FL. Shear values are still probably a little too high--about 10 knots--to permit a tropical depression to form in this region today. However, the shear is forecast to decrease, and a tropical depression could form Tuesday or Wednesday. The computer models are less agressive developing this system today, but still indicate a tropical storm could form here and very slowly move northwards along the coast of Florida towards the Carolinas.

A second disturbance with a well-defined circulation visible on both visible satellite images and QuikSCAT data is located about 600 miles east of Cape Canaveral, Florida. A concentrated area of deep convection has developed on the south and east sides of the circulation center. There is no convection over the center, which would have to happen before the system can be classified as tropical depression. Highest winds observed by the QuikSCAT satellite are about 20 knots. Shear values are about 10 knots, which is marginal for development, but the shear is likely to decrease some today and tomorrow, and this system has a good chance of becoming Tropical Depression 15. The system is expected to move slowly northwestward and meander in the area between Bermuda and the Carolinas.


Figure 1.Forecast track of tropical low 600 miles east of Cape Canaveral, FL.

African tropical waves
The tropical wave we've been watching cross the Atlantic for the past week is still out there, 300 miles east of the islands. This system has now moved far enough north that it may have a chance to develop later in the week as it moves through the Caribbean Sea.

A huge low pressure system accompanied by a large cloud of Saharan dust moved off of Africa yesterday. The dry air associated with the African dust will inhibit any development of this low.

Hurricane Maria
Hurricane Maria is a pretty sight on satellite images, with a large, well-formed eye. She may continue to intensify and reach Category 3 status by tomorrow as she heads northward and then northeastward out to sea. Expect Maria to die by Friday when cold water and wind shear take their toll.

Jeff Masters