Tropical Storm Chantal (2001) - Meteorological History

Meteorological History

A tropical wave moved off the coast of Africa on August 11. Associated deep convection quickly decreased after tracking westward through the tropical Atlantic Ocean, although by August 13 a broad low pressure area and closed circulation developed along the wave. Environmental conditions favored tropical development, and the system gradually became better organized, although convection was initially limited near the center. On August 14, convection increased northwest of the center and became sufficiently well-organized for the system to be considered a tropical depression; at the time, it was located about 1500 miles (2400 km) east of the southern Windward Islands.

Situated to the south of a strong subtropical ridge, the depression tracked rapidly westward. With easterly wind shear, the structure was initially disorganized, although the system was forecast to attain tropical storm status within 48 hours of developing, due to anticipated favorable conditions. One computer model predicted the depression would reach winds of around 115 miles per hour (185 km/h) by four days after development. Banding features increased while the satellite presentation continued to improve, and at 1200 UTC on August 16 the depression was upgraded to Tropical Storm Chantal about 370 miles (595 km) east of Barbados. At the same time however, a QuikSCAT pass suggested the system did not contain a low-level circulation, and in post-season analysis, the National Hurricane Center estimated the system degenerated into a tropical wave rather than attain tropical storm status. This was confirmed by a Hurricane Hunters flight into the system.

Despite lacking a closed circulation, the overall structure remained well-organized, and with a favorable upper-level environment the possibility of regeneration into a tropical cyclone was noted. Early on August 17, the remnants of Chantal passed over the Windward Islands with winds of tropical storm force. After entering the Caribbean Sea, the system slowed while its convective pattern expanded and became more symmetric. Hurricane Hunters confirmed that a small circulation developed about 290 miles (265 km) south of Saint Croix, and accordingly the system developed into a tropical storm. Forecasters described the upper-level environment as "ideal for tropical cyclone to intensify", with winds of 80 miles per hour (130 km/h) forecast within a few days. The cyclone was predicted to maintain a west-northwestward track toward the northwestern Caribbean and Gulf of Mexico. On August 18, the winds increased to 65 miles per hour (105 km/h), although an increase in forward motion caused the low-level circulation to become separated from the deep convection. The storm again decelerated on August 19, allowing re-organization and for Chantal to attain peak sustained winds of 70 miles per hour (110 km/h) about 185 miles (295 km) south of Kingston, Jamaica.

After reaching peak winds, Tropical Storm Chantal became disorganized while the center became ill-defined and situated to the west-southwest of the main area of convection; this was due to unfavorable upper-level winds, although computer models continued to forecast a more favorable upper-level environment. By early on August 20, Hurricane Hunters reported several low-level circulations embedded within a large low pressure area. Later that day, wind shear decreased when the storm moved into the Gulf of Honduras. Chantal became much better organized, again reaching peak winds of 70 miles per hour (110 km/h) before making landfall early on August 21 near the border of Mexico and Belize. Initially, the storm was forecast to cross the Yucatán Peninsula and Bay of Campeche and make a second landfall in the state of Veracruz. Chantal slowly weakened over land while moving slowly across northern Belize. Convection decreased markedly late on August 21, and early the next day Chantal weakened to tropical depression status. The upper- and middle-level circulations turned to the northeast while the low-level circulation turned to the west-southwest further inland. Weakening continued, and late on August 22 Chantal dissipated over the Mexican state of Tabasco.