Preliminary Report
Tropical Storm Charley
21 - 24 August 1998

1998 PRELIMINARY REPORTS

Tropical Storm Alex (TS)
Hurricane Bonnie (3)
Tropical Storm Charley (TS)
Hurricane Danielle (2)
Hurricane Earl (2)
Tropical Storm Frances (TS)
Hurricane Georges (4)
Tropical Storm Hermine (TS)
Hurricane Ivan (1)
Hurricane Jeanne (2)
Hurricane Karl (2)
Hurricane Lisa (1)
Hurricane Mitch (5)
Hurricane Nicole (1)

a. Synoptic History

The origin of Tropical Storm Charley is unclear. It could have been a large swirl of clouds that exited the coast of Africa on 9 August at rather high latitude, mainly to the north of Dakar, Senegal. More definitely, the precursor consisted of a small area of deep convection first noted a few hundred miles to the northeast of the Leeward Islands on the 15th. Intermittent convective activity continued while the system moved just west of north for the following few days. On the 19th, animation of satellite pictures showed a cyclonic rotation of the clouds over the southeastern Gulf of Mexico.

The first formal position estimate from satellite analysts came on the evening of the 19th and Dvorak T-numbers (1.5) were first assigned the next day over the central Gulf. By the morning of the 20th, surface winds had begun to increase, with NOAA's central Gulf buoy 42001 measuring sustained winds as high as 36 mph and gusts to 52 mph at 1700 UTC. These stronger winds were fleeting, however, and an investigation of the system late that day by U.S. Air Force Reserves reconnaissance aircraft did not indicate a closed low-level circulation center.

A center "fix" was made aboard reconnaissance aircraft early in the following flight, near 1300 UTC the next day, and this is the basis for indicating that the system became a tropical depression around 0600 UTC on the 21st. At that time, the depression was centered about 275 nautical miles off of the south Texas coast. The tropical cyclone moved toward the west-northwest to northwest at about 12 mph during its three-day lifetime.

Although the center was not well-formed initially, the amount of deep convection steadily increased, particularly over the northern semicircle. That part swept over the oil platforms of the northern Gulf and data from them (e.g., Table 2) suggest that tropical storm status was reached by 1800 UTC on 21 August. Winds of hurricane force were noted in intense convection to the northeast of the center at a flight level of 1500 feet early on the 22nd. Charley was likely then at its peak strength, near 69 mph. The wind speeds measured aboard aircraft were considerably lower thereafter and it is estimated from that data and other observations that surface winds were closer to 46 mph when Charley's center made landfall near Port Aransas about 1000 UTC on the 22nd.

The surface circulation weakened further after landfall and likely dissipated early on the 24th along the Rio Grande near Del Rio, Texas. Although the winds diminished inland, and a closed surface circulation could no longer be identified, a slow-moving circulation aloft persisted in the Del Rio vicinity and generated flooding rains that were most devastating in that area on the 23rd and 24th. By late on the 25th, most of the remnant cloud system had deteriorated and precipitation had diminished.

b. Meteorological Statistics

The ASOS sites at Rockport (RKP) and Galveston (GLS), Texas were the only two surface reporting stations on land to measure sustained tropical storm force winds. They recorded 2-minute winds of 41 mph and 39 mph, respectively. A gust to 63 mph was reported from the Pt. O'Connor Coast Guard.

A minimum pressure of 1000 mb is estimated at landfall from the observation of 1000.7 mb at RKP an hour later.

1. Storm Surge Data

Storm tides of 2 to 3.5 feet above normal astronomical levels were reported from the coast.

2. Rainfall Data

Charley's primary legacy will be the rainfall and associated flooding it produced in the Del Rio vicinity. On 23 August, 16.83 inches of rain fell in Del Rio. This easily surpassed the previous daily record of 8.79 inches on 13 June 1935. A nearby site recorded 17.59 inches for the 24 hour period ending in the morning hours of 24 August. Along the coast, maximum rainfall totals were near 5 inches except for an unofficial report of 9 inches near the mouth of the San Bernard River in Brazoria County.

River flooding along the Rio Grande occurred well downstream from Del Rio, in the Laredo area.

c. Casualty and Damage Statistics

There were 20 deaths attributed to Charley; 13 in Texas and 7 in Mexico.

All the Texas casualties were apparently flood victims located well inland. The total consists of four people including two toddlers whose pickup was swept away by rising water in Real County on the 23rd. Seven other people from the truck were rescued. Nine deaths due to drowning occurred in Del Rio (Val Verde County) along the San Felipe Creek during the late night of 23 August. Some in the latter group could have expired after the system was no longer classified as a tropical cyclone.

Emergency operations personnel in Mexico reported that as of early October the number of fatalities in Ciudad Acuña, Mexico, across the border from Del Rio, was seven. Media reports indicate that three of these victims drowned while trying to cross a flooded gully.

A preliminary estimate of the total loss due to the inland flood is $50 Million. Property losses were reported in several counties and consisted of damages to residences, businesses, roads, bridges and agriculture. About 1500 homes, 200 mobile homes, and 300 apartments were damaged or destroyed in Val Verde County, where about $40 Million in losses occurred.

Minor beach erosion was reported.