a. Synoptic History
Hurricane Dolly formed from a tropical wave of large lateral
extent that moved from the west coast of Africa to the central Caribbean
Sea during 9-18 August 1996. Although the wave generated deep convection
when it emerged from Africa, there was little accompanying thunderstorm
activity for much of its passage across the tropical North Atlantic Ocean.
Deep convection redeveloped when the wave reached the eastern Caribbean,
but did not persist in a concentrated pattern until the system was south
to southwest of Jamaica on the 18th-19th. A low- to mid-level cyclonic
circulation was then detected in data obtained during a NOAA research
flight to study the development of tropical cyclones. Satellite analysts
indicated that the system was too weak to classify using the Dvorak technique
late on the 18th, but they calculated Dvorak T-numbers of 1.5 and 2.0
on the afternoon of the 19th. By mid-afternoon on the 19th, the first
center "fix" by reconnaissance aircraft was made and data from the plane,
satellite, and a ship that reported 52 mph at 1800 UTC were used to
estimate that the tropical depression stage began with a poorly-defined
circulation center near 0600 UTC on the 19th, and that the depression
became Tropical Storm Dolly a little more than six hours later.
The tropical cyclone developed near or just south of a mid-
to upper-level anticyclone. In that environment, Dolly strengthened on
the 19th and 20th and moved toward the west-northwest at a speed that
decreased from 17 mph to about 9 mph. Convection became better organized
near the circulation center on the 20th and, just before making landfall
on the Yucatan peninsula to the northeast of Chetumal, Dolly became a
hurricane. It weakened back to a tropical depression and slowed to about
6 mph during its 24-hour passage over the peninsula, and satellite pictures
showed the center of cloud rotation displaced to the south of the estimated
surface circulation center.
Gradual restrengthening began a few hours after the surface
center arrived over the Bay of Campeche. Dolly regained hurricane status
and was at it strongest, with 81 mph winds and a central pressure of
989 mb, when it accelerated to 17 mph and made its final landfall about
midway between Tuxpan and Tampico near 1800 UTC on the 23rd.
Dolly then weakened and, as a tropical depression, crossed
central Mexico. It continued to generate areas of deep convection and,
likely, heavy precipitation even while its surface center dissipated over
the eastern North Pacific Ocean on the 25th.
b. Meteorological Statistics
The only available official observations of at least tropical
storm force winds from a surface land site came from Tampico, Mexico.
There, 10-minute winds of 46 mph with gusts to 69 mph occurred at
1045 UTC and 1145 UTC on the 23rd. An amateur radio report of a gust to
68 mph was received from Tampico.
1. Rainfall DataThe three largest 24-hour rainfall totals reported to the meteorological service of Mexico came from Micos (12.94 inches), Santa Rosa (10.59 inches), and Puerto de Valles (10.00 inches). The rains, which in some cases were heavier on Mexico's west coast than its east coast, also occurred in the more widely-known cities of Acapulco (7.48 inches), Los Mochis (7.06), Tuxpan (5.88 inches), Chetumal(5.73 inches), Monterrey (4.93 inches), and Cancun (1.35 inches).
c. Casualty and Damage Statistics
There were 14 deaths attributed to Dolly; 14 in Mexico.
Those reports also indicated hundreds of residences destroyed
and 35,000 people displaced. Severe damage occurred in Tuxpan, Tamiahua,
Pueblo Viejo, Platon, Panuco, Tampico Alto and elsewhere along the coast
of northeast Mexico. A river overflowed its banks causing damage in Pueblo
Viejo. A large area of farm land was lost to flooding in Quintana Roo
on the Yucatan peninsula.
Rain prompted evacuations in the southern part of the state
of San Luis Potosi. About 6500 people were evacuated from low-lying zones
Widespread communication and power outages were noted as far west as Mazatlan.
Maximum Intensity For Hurricane Dolly