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TD 11, TD 10, and African waves

By: Dr. Jeff Masters, 5:41 PM GMT on August 22, 2005

Tropical Depression 11
TD 11 will be the 4th tropical cyclone to hit the east coast of Mexico this year, and the 3rd weak system to affect the extreme southern Bay of Campeche. It looks almost exactly like Tropical Storm Gert of July. TD 11 will probably intensify enough be called Tropical Storm Jose before landfall tonight, but will be quickly forgotten.

The Hurricane Hunters will investigate the system at 5pm EDT, and one might wonder why NHC bothers with the expense of sending a plane out to an obviously low-threat storm with only a few hours to live. The answer is that these storms are full of surprises, and it is NHC's policy to have an airplane in a storm anytime one threatens land just in case sudden strengthening happens.

Remains of TD 10
The remains of TD 10 are still hanging around the Bahamas-Cuba-Hispanolia area, but continue to look disorganized. Expect this activity to continue moving west at 10 mph with no development over the next two days.

East Coast frontal boundary
Some development is possible off the East Coast later this week near the Carolinas at the trailing edge of a cold front that moved off the coast yesterday. This kind of development is common this time of year.

African waves
The large tropical wave that moved off the coast of Africa Friday night continues to spin and track west-northwest, and is now about 400 miles west of the Cape Verde Islands. The convection associated with this wave has not increased at all the past few days. If the wave does develop, it will probably recurve in the center of the ocean and not affect any land.

I've been calling attention the past few days to the GFS model's prediction of increased hurricane activity over the mid-Atlantic beginning late this week. This morning's GFS model run is now backing off from that prediction, and only shows one instead of three tropical cyclones in the Atlantic on August 31 (the one cyclone is the current wave 400 miles east of the Cape Verde Islands, which the GFS forecasts to recurve north of the Azores Islands). The GFS does show that the ITCZ will be very active, with many stong tropical waves pushing off of the coast of Africa. A new tropical wave is pushing off of the coast of Africa today, but it is too early too see if this wave has potential to develop.

The level of tropical activity we are seeing this week is typical of what one sees during the peak of an average hurricane season (hurricane season peaks on about September 10). It will be interesting to see if the GFS's earlier prediction of much-above average activity by next week will come back with newer runs of the model.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.