A tropical wave moved offshore the western African coast on July 22nd.  While the northern
portion of the wave spawned Tropical Storm Erin, the southern portion moved west through
the Caribbean Sea.  By August 1st, a weak low had formed over the northwest Caribbean Sea.
The system moved westward through the Yucatan peninsula on the 2nd and 3rd, entering the
Bay of Campeche on the 4th.  Meanwhile, an area of convection formed across the Mexican
Isthmus, which moved northwest to a location coincident with the surface low.  By the 5th,
the system was well enough organized to be considered a tropical depression.  The depression
moved west-northwest, crossing the Mexican coast midway between Tampico and Tuxpan on
the evening of the 6th.  The area of low pressure associated with the depression quickly dissipated,
but its cloud pattern retained integrity until the afternoon of the 7th before dissipating.  Below are
storm total rainfall maps for the depression, using data provided by the Comision Nacional del
Agua, the parent agency of Mexico's national weather service.