TD 15 forms by African coast, also closely watching Gulf of Mexico

Enhanced satellite image of Tropical Depression 15. (EUMETSAT)

On Monday afternoon, a very strong and late African wave developed into Tropical Depression 15, way out at 20.2°W -- just 200 miles offshore! The Cabo Verde season, in which tropical waves exit the African coast near the Cabo Verde islands, typically spans mid-August through mid-October... but by mid-October it's pretty meager. As Phil Klotzbach at CSU pointed out, this is the easternmost tropical cyclogenesis this late in the year on record.

The forecast is not very threatening to anyone though. It may never reach tropical storm status as it passes by the Cabo Verde islands then off toward the northwest where it is forecast to dissipate.

Elsewhere, a disturbance over central America has some potential for development in the Gulf of Mexico later this week.  The National Hurricane Center is giving it a 40% chance of development into at least a depression by the end of the weekend.

Global model ensembles are divided on the system developing on the west side of Mexico or the east, but the trend has been shifting eastward, favoring the Gulf.  At this point, model guidance does not suggest that it becomes anything too strong, but that can change at this long lead time. So we will just keep a very close eye on it and model trends... especially interests in the western Gulf this weekend.  The next name on the list is Nestor.

Looking back to the start of the satellite era in 1960, I could find just seven named storms that developed in the western Gulf after October 1.  The two most recent were Marco (2008) and Matthew (2004). Jerry (1989) is the one that made landfall near Galveston as a Category 1 hurricane on October 16.

Tracks of seven named storms that formed in the western Gulf after October 1 (1960-2018).

Today is also the 14th anniversary of Hurricane Wilma's formation (Tropical Depression 24 at the time).  If you missed it on Twitter, there's a thread with new and interesting graphics at https://twitter.com/BMcNoldy/status/1184106020299104261

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