Tropical Depression Twelve developed from a tropical wave that moved off the coast of Africa on 30 September. Satellite classifications on the system began on 3 October. Based on satellite classifications and cloud drift wind vectors from the University of Wisconsin, the system is estimated to have become a tropical depression on the 6th. Over the next three days, the depression moved somewhat erratically to the west-northwest without development. During this time, the low-level circulation center was mostly on the west side of the deep convection, due to the presence of an upper trough/low to the cyclone's north. Convection diminished on the 8th and the depression dissipated as the low-level circulation became less well defined. The remnant low-level cloud swirl could be tracked for several days thereafter as it continued west-northwest and then westward before dissipating completely north of the Lesser Antilles.
The "best-track" for the depression is given in Table 1.
Table 1. Best track for Tropical Depression Twelve, 6-8 October 1999. Date/Time
(UTC)Position Pressure
(mb)Wind Speed
(kt)Stage Lat. (°N) Lon. (°W) 06/0000 14.4 44.8 1008 30 tropical depression 06/0600 14.8 45.4 1008 30 " 06/1200 15.0 45.8 1007 30 " 06/1800 15.2 46.0 1007 30 " 07/0000 15.4 46.2 1008 30 " 07/0600 15.6 46.5 1008 30 " 07/1200 15.8 46.7 1008 30 " 07/1800 16.0 47.1 1008 30 " 08/0000 16.4 47.5 1008 30 " 08/0600 16.6 47.7 1008 30 " 08/1200 16.8 47.9 1008 30 " 08/1800 17.3 48.5 1010 25 " 06/1200 15.0 45.8 1007 30 minimum pressure