"In looking at best track data since 1851, for the entire year, Dorian is among around 50 to 60 storms to form as far east. (Dorian's best track data is subject to revision, and has been revised at times today, so an exact point of origin is still subject to change.) However, this early in the year, through July 31st, Dorian formed further east than all but one storm, Hurricane Bertha in 2008, which became a tropical storm on July 3rd, 2008 about 3 to 5 degrees east of where Dorian formed.

If Dorian's best track data holds at it becoming a 45 knot tropical storm at 29.0W, it would beat out Hurricane Bertha in 2008 at attaining that level of development this early in the year, through July 31st, that far east. Hurricane Bertha reached an intensity of 45 knots at 29.2W on July 4th, 2008. The next storm to achieve that level of development, 45 knots, further east is Hurricane Alberto in 2000 which achieved that level of development at 28.2W on August 5th, 2000.

Tropical Storm Chantal, earlier this month, was notable for its development so early in the year at such a southern latitude.

Dorian is the fourth named storm of the 2013 Atlantic hurricane season. In looking at data from 1966 through 2009, the average date of the fourth named storm in the Atlantic is August 23rd, making 2013 about a full month ahead of average in terms of named storms. However, the average date of the first hurricane in the Atlantic is August 10th and 2013 has yet to see a hurricane, although that average date of formation is still over two weeks away. (http://www.nhc.noaa.gov/climo/#bac)"