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Preliminary Report
Hurricane Dolly
19-25 August 1996

Edward N. Rappaport
National Hurricane Center
3 October 1996

Tropical Storm Arthur
Hurricane Bertha
Hurricane Cesar
Hurricane Dolly
Hurricane Edouard
Hurricane Fran
Tropical Storm Gustav
Hurricane Hortense
Hurricane Isidore
Tropical Storm Josephine
Tropical Storm Kyle
Hurricane Lili
Hurricane Marco


 Visible image of Hurricane Dolly making landfall on the Yucatan Peninsula of Mexico, 2100 UTC 20 August. (368K GIF)

[1996 Atlantic Hurricane Season]

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 45 knots 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 (Table 1, Fig. 1 [49K GIF]) at a speed that decreased from 15 knots to about 8 knots. 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 5 knots 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 70 knot winds and a central pressure of 989 mb, when it accelerated to 15 knots 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 "best track" (Table 1) was obtained from the data presented in Figs. 2 (32K GIF) and 3 (39K GIF), and in Table 2. Those figures show Dolly's estimated central pressure and maximum one-minute wind speed, respectively, versus time. Position and intensity estimates from satellite pictures were provided by the NOAA Synoptic Analysis Branch (SAB) and Tropical Analysis and Forecast Branch (TAFB), and by the Air Force Global Weather Central (AFGWC). This information was supplemented by reconnaissance aircraft data provided by the U.S. Air Force Reserves, and surface observations from land sites and ships.

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 40 knots with gusts to 60 knots occurred at 1045 UTC and 1145 UTC on the 23rd. An amateur radio report of a gust to 59 knots was received from Tampico.

Ship reports of 34 knot or higher wind speeds are listed in Table 2.

The 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

According to newspapers reports, Hurricane Dolly was responsible for fourteen deaths in Mexico--including six in Veracruz (all drowned), three in Nuevo Leon, and one each in Pueblo Viejo and Monterrey. Two people were missing in Nuevo Leon.

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 of Tampico.

Widespread communication and power outages were noted as far west as Mazatlan.

d. Forecast and Warning Critique

Table 3 provides track forecast error statistics. The cyclone was relatively short-lived and only five forecasts through 72 hours could be evaluated. The best model performance was made by BAMD which had astonishingly small errors (e.g., average error of 31 nm at 72 hours). The NHC average track forecast errors were not as small as those of the BAMD, but were much smaller than the those of the GFDL, VBAR, and the interpolated GFDI and UKMI guidance. The NHC errors were smaller than the most recent 10-year average, as well. Most NHC intensity forecast errors were 15 knots or less.

Table 4 lists tropical storm and hurricane watches and warnings issued by the government of Mexico.

Table 1. Preliminary best track, Hurricane Dolly, 19-25 August 1996.
Position Pressure
Wind Speed
Lat. (°N)Lon. (°W)
19/060017.380.2100925 Tropical Depression
120017.881.7100830" "
180018.283.0100645 Tropical Storm
20/000018.684.4100645" "
060018.885.7100555" "
120019.086.9100260" "
21/000019.288.7100140 Tropical Storm
060019.389.5100235" "
120019.490.1100230 Tropical Depression
180019.590.7100230" "
22/000019.791.4100235 Tropical Storm
060020.192.6100245" "
120020.493.799945" "
180020.694.299350" "
23/000020.994.999055" "
060021.396.199160" "
180021.699.399745Tropical Storm
24/000021.6100.9100230 Tropical Depression
060021.6102.5100425" "
120021.7104.0100520" "
180021.7105.7100520" "
25/000021.8107.3100520" "
25/0600     Dissipated
23/120021.697.798970 Minimum Pressure
Landfall information:
Near Punta Herrero, Mexico (northeast of Chetumal)
Midway between Tampico and Tuxpan, Mexico

Table 2. Ship reports of at least 34 knots
wind speed
Iver Explorer19/180018.282.045 1007.9
Golfo Di Trieste20/030019.283.3361013.0(?)
Celebration20/030021.384.335 1001.3(?)
unknown20/060020.686.337 1014.8(?)
Titan Scan20/120018.682.937 1010.9
Titan Scan20/180019.783.937 1012.3
Columbus Queensland20/180021.986.234 1015.0
Titan Scan20/210020.284.337 1011.5

Table 3
Preliminary forecast evaluation of Hurricane Dolly
Heterogeneous sample (Errors in nautical miles for tropical storm and hurricane stages with number of forecasts in parenthesis)
Forecast TechniquePeriod (hours)
GFDI71 ( 7)119 (5)184 (5)236 (5)415 (3)
GFDL *41 ( 4)108 (3)145 (2)215 (3) 341 (2)
VBAR34 (11) 82 (9)154 (7)259 (6)404 (5)
LBAR35 (11) 50 (9)102 (7)190 (6)290 (5)
AVNI56 ( 2)193 (1)323 (1)289 (2) 95 (2)
BAMD35 (11) 40 (9) 46 (7) 49 (6) 31 (5)
BAMM34 (11) 48 (9) 77 (7)114 (6)126 (5)
BAMS37 (11) 52 (9) 92 (7)129 (6)128 (5)
A90E42 (11) 55 (9) 91 (7)134 (6)181 (5)
CLIP45 (11) 54 (9) 94 (7)107 (6)132 (5)
NGPI (0) (0) (0) (0) (0)
UKMI77 ( 4)129 (2)200 (2)256 (1)306 (1)
NHC OFFICIAL40 (11)53 (9)94 (7)(6)182 (5)
(1986-1995 10-year average)
49 (1670)93 (1484) 36 (1314)181 (1155)273 (882)

* GFDL output not available until after forecast issued. VBAR output sometimes not available until after forecast issued.

Table 4. Tropical Cyclone watch and warning summary, Hurricane Dolly
19/1800 Tropical Storm Warning issued Chetumal to Progreso, Mexico
Tropical Storm Watch issued Pinar del Rio Province and Isle of Pines, Cuba
19/2100Tropical Storm Warning issued San Pedro, Belize to Mexico border
20/1200Tropical Storm Watch discontinued Cuba
20/1500Tropical Storm Warning issued Progreso to Ciudad del Carmen
20/1600 Hurricane Warning issued--replaced Tropical Storm Warning Cozumel to Chetumal
20/2100 Hurricane Warning and Tropical Storm Warning discontinued South of Cozumel
21/0300Tropical Storm Warning discontinued eastward from 88W
21/0900Tropical Storm Warning discontinued east of Progreso
21/1500Tropical Storm Warning discontinued remainder of Mexico
22/0900Hurricane Watch issued Veracruz to La Pesca, Mexico
22/1500 Hurricane Warning issued-replaced Hurricane Watch Veracruz to La Pesca
23/1800 Hurricane Warning discontinuedVeracruz to La Pesca

Brian Maher
Jack Beven

Last updated December 28, 1998