A central Atlantic tropical cyclone in June is a rare event but Invest 92L seems destined to develop into one. Clark has pointed out how unusual it is for a tropical cyclone to develop in the middle of the basin in June at such a far eastern and far southern location. I examined all of the seasons since the start of the satellite era in 1964 to see just how often a tropical cyclone forms at a latitude of 10 degrees North or less in any month. The historical record was limited to only those storms that eventually became at least a tropical storm.

Those 46 seasons produced 494 tropical storms/hurricanes and subtropical storms with 18 Tropical Depressions forming at a latitude below 10 degrees (3.6% of the total number of storms). Four of the 18 became a tropical storm at or below 10 degrees North latitude. In 1990, Fran became a tropical storm at 9.0N 53.6W. Also in 1990, Isidore became a tropical depression at 7.2N 23.4W and a tropical storm at 10.0N 32.7W. In 2002, Dolly became a tropical storm at 9.7N 32.2W and in 2004, Ivan became a tropical storm at 9.7N 35.0W. Ivan was unique in that it dipped south of due west and became a 50 knot TS at 8.9N 36.5W, a hurricane at 9.5N 43.0W and reached a sustained wind of 115 knots at 10.6N 48.5W. Joan (1988) gets honorable mention with TS status at 10.1N 45.0W.

Invest 92L has a chance to join this short list if it should attain TD status while still below 10 degrees in latitude.
ED