In mid-July, 2011, a broad upper
trough dropped southward over the northwest
Atlantic, supporting a
cold front that extended westward across
Bermuda to inland over
Georgia. The front produced a large area of light showers to its north, with its westernmost component remaining quasi-stationary over northeastern
Florida. On July 16, a
surface low developed along the decaying
boundary, just off the coast, generating an area of sporadic
convection north of the
Bahamas. Although a wind circulation was initially absent and
surface pressures were relatively high, the low later became better organized under abating
shear conditions on July 17.
A reconnaissance flight observed a closed circulation center about , northwest of
Great Abaco Island at 18:00 UTC that day, which confirmed the formation of a tropical depression. Just three hours later, the
National Hurricane Center (NHC) issued its first advisory on the depression, and upgraded it to Tropical Storm Bret at 03:00 UTC the next day, owing to a quick increase in winds and thunderstorms around its center. Situated along a weakness in the
subtropical ridge, Bret drifted very slowly southward during the initial stages of its existence.
Satellite images displayed a disorganized
eye-like feature on July 18, suggesting a rather sharp increase in strength. Indeed, an additional reconnaissance flight into the cyclone found peak surface winds of around , just below hurricane strength. Following its peak, Bret began to accelerate toward the northeast in response to building
high pressure in the area. It fluctuated little in intensity for several hours, although a combination of high wind shear and a lack of tropical moisture inhibited further development. By July 19, the circulation center had become exposed and devoid of deep convection, and the storm weakened to winds upon moving through the increasingly hostile environment. Despite the unfavorable conditions, Bret retained this intensity for the next couple of days as it briefly slowed, with a distinct low-level circulation and a few patches of persistent thunderstorms over its southwestern
quadrant. Early on July 20, the heavily sheared cyclone began to reaccelerate within the deepening southwesterly
wind flow. Over the next day, Bret continued to deteriorate in organization; however, a brief decline in the upper winds allowed intermittent bursts of convection to redevelop south of the exposed center. Bret eventually weakened to a tropical depression over
cool ocean temperatures early on July 22, once again lacking significant convection while increasing in forward speed. Forecasters at the NHC noted that Bret remained "a maverick tropical cyclone by refusing to dissipate despite experiencing very hostile wind shear conditions," with
ship data indications of prevailing strong winds. By 1500 UTC, however, the circulation had become ill-defined, prompting the NHC to declassify Bret as a tropical system about north of
Bermuda. During the next several hours, the remnant low of Bret continued to move northeastward out into the Atlantic, until it dissipated on July 23. ==Preparations and impact==