12 October 2019

Melissa forms off northeast U.S. coast

Tropical Storm Melissa, the season's 13th named storm, began its journey over North Carolina on Monday, then left the coast on Tuesday and continued to slowly organize... it was finally upgraded to a subtropical storm on Friday morning.  However, it may only be around for another day or so. Melissa will be yet another short-lived and messy storm this year, similar to Andrea, Chantal, Erin, Fernand, and Imelda -- those five storms combined were named for less than four days!

Peak sustained winds are at 50 mph and further weakening is expected as it accelerates toward the east into higher wind shear and colder water.  There are no associated tropical storm or storm surge watches/warnings. The storm is very tiny; the tropical storm force winds extend an average of just 45 miles from the center!

The recent transition from a subtropical cyclone to a tropical cyclone is nicely illustrated in this cyclone phase space diagram. It's a bit technical, but the low starts at location A on Wednesday, it's presently at location C on Saturday, and the forecast is at location Z on Friday. In this model-based analysis of the storm's structure, we see that it began as an asymmetric warm-core system (subtropical), it migrated into the symmetric warm core realm (tropical), is currently in a near-neutral zone, and is headed for the asymmetric cold core realm (extratropical).  So, while these classifications have a bit of subjectivity to them, there is also an objective foundation on which the transition is based.

Cyclone phase space diagram for Tropical Storm Melissa. (FSU)

Elsewhere, the Atlantic basin should be quiet for the foreseeable future. But don't tune out just yet... even late October has a history of producing some infamous storms!

1 comment:

  1. Happy to see a direct link to the story in the email. Thanks for all your reports during the season.

    H Davis