Short-lived Tropical Depression Seven developed when a strong monsoon-type flow, which extended northward through eastern Mexico interacted with a tropical wave in the Bay of Campeche. Unexpectedly, on the 5th of September, early morning high resolution visible satellite images showed a well defined low-level circulation and organized convection in the Bay of Campeche. It was estimated that the tropical depression formed at 1800 UTC 5 September near Tampico. Because it was forecast to reach tropical storm status, a tropical storm warning was then issued for the coast of Mexico from Tampico to Matamoros. The depression was becoming better organized just before landfall as indicated by the well-defined center depicted in Fig. 1. The depression moved slowly toward the northwest and moved inland around 1200 UTC 6 September in the vicinity of La Pesca (Fig. 1) producing heavy rains over northwestern Mexico and southern Texas. The circulation of the tropical depression was clearly observed on the WFSO Brownsville radar. Table 1 is a listing, at six-hourly intervals of the best-track position, estimated minimum pressure and maximum 1-minute sustained surface wind speed.
Figure 1. TRIMM 37V microwave data at 0811 UTC 6 September and high resolution visible satellite image at 1445 UTC 6 September just after landfall provided by NRL.
Table 1. Best track, Tropical Depression Seven, 5- 7 September, 1999 Date/Time
(UTC)Position Pressure
(mb)Wind Speed
(kt)Stage Lat. (°N) Lon. (°W) 5/1800 21.6 96.4 1006 25 tropical depression 6/0000 22.0 96.7 1006 30 " 0600 22.6 97.2 1006 30 " 1200 23.2 97.7 1006 30 " 1800 23.8 98.0 1006 30 " 7/0000 24.0 98.1 1006 30 " 0600 24.3 98.5 1006 30 " 1200 25.0 99.0 1007 25 dissipating 6/1200 23.2 97.7 1006 30 landfall near La Pesca