Tropical Storm Don 2011

Tropical Storm Don developed after being classified as an invest for nearly a week. The fourth tropical cyclone and fourth named storm of the 2011 Atlantic hurricane season, Don developed on July 27 from a persistent tropical wave in the southeastern Gulf of Mexico.

Meteorological history

The genesis of Tropical Storm Don was from a tropical wave first identified off the west coast of Africa in mid-July. Preceded by a surge of deep tropical moisture, it tracked westward over the open Atlantic for several days, with minimal convection confined to the monsoon trough. Throughout its journey, the wave became increasingly embedded within a broad area of cyclonic wind flow, enhancing the convection. The National Hurricane Center first mentioned the potential for gradual tropical cyclogenesis on July 21, when it was positioned about 750 mi (1200 km) to the east of the Windward Islands. As it neared the islands the next day, it briefly became better defined, although a spell of vertical wind shear and proximity to land impeded further development. Still in the vicinity of abundant moisture, the system generated largely scattered thunderstorms over much of the northeastern Caribbean, all the while deteriorating in organization.

Convection waxed and waned for several days during its passage through the Greater Antilles, and by July 25 significant redevelopment was not expected. The following morning, however, shower and thunderstorm activity reintensified south of western Cuba while the wave retraced to the west-northwest and slowed. It continued to gain in organization over the waters of the Yucatán Channel; radar data early on July 27 suggested a surface circulation was in the process of forming. In addition to surface wind estimates of 40 mph (65 km/h), a reconnaisance aircraft flight into the system confirmed the presence of a closed albeit elongated circulation center, prompting the NHC to initiate advisories on Tropical Storm Don at 2100 UTC that day. At the time, it was located about 120 mi (190 km) north of Cozumel, Mexico, steered along the southern periphery of a low- to mid-level ridge over the northern Gulf of Mexico.

Preparations

After the storm was named, officials in Texas began making preparations for Don. The University of Texas Medical Branch in Galveston issued a level one alert for Don, and city officials began preparing for a possible evacuation.

On July 27, Oil companies throughout the western Gulf of Mexico began removing non-essential personnel from their rigs and platforms in preparation for the storm. The next day, BP, Royal Dutch Shell, Anadarko and Apache announced the evacuations of some of the oil facilities in the area, while Exxon-Mobil began preparing the Baytown Refinery for a possible strike from the storm.

The state civil protection agency in Quintana Roo warned that the tropical wave from which Don formed was capable of dropping 80 to 150 mm (3.1 to 5.9 in) of rainfall over the state, while producing sustained winds of 35 to 45 km/h (22 to 28 mph) and gusts up to 65 km/h (40 mph). After Don was designated as a tropical storm, the Yucatán state government issued a green-level alert. The alert indicated that although the tropical storm was located close to the state, it was only considered to be slightly dangerous.

Late on July 27, the National Hurricane Center issued Tropical Storm Watches from Port Mansfield, Texas to San Luis Pass, Texas. Six hours later, the Tropical Storm Watch was extended southwards to the international border.

Impact

Several oil companies stopped oil production as a result of Don; by midday on July 28, 6.8% of oil production and 2.8% of natural gas production in the Gulf had been shut in ahead of the storm.

Current storm information

As of 4 p.m. CDT (2100 UTC) July 28, Tropical Storm Don is located within 30 nautical miles of 24.9°N 91.3°W, about 425 mi (690 km) east-southeast of Corpus Christi and about 395 mi (635 km) east of Brownsville. Maximum sustained winds are 40 knots (45 mph, 75 km/h), with stronger gusts. Minimum central pressure is 1005 mbar (hPa; 29.68 InHg), and the system is moving northwest at 14 kt (16 mph, 26 km/h).

Tropical storm force winds extend outward up to 85 miles (140 km) from the center of Don.