2011 Florida Subtropical Storm
Formed October 4, 2011
Dissipated October 10, 2011
Lowest pressure 999 mbar
Damage N/A
Fatalities N/A
Florida, Cuba, and the Bahamas
Part of the
2011 Atlantic hurricane season

SUBTROPICAL STORM INVEST 93L was subtropical storm that formed on October 9th, made landfall an hour later and lost subtropical characteristics on October 10th. It formed from a strong pressure gradient over Florida and off the coast. This pressure gradient caused vertical instability and caused convection to fire and this convection gradually became better defined and formed a low pressure area. As the low headed north, Florida radar showed a well-defined center forming. Weather reports from buoy and land stations showed that at this time there was also a low level circulation forming. As the storm made landfall a AMSU satellite pass showed that the storm had a warm core and organized convection. Buoy reports and land stations also showed that a low level circulation had fully developed at that time and that the low pressure system had attained at the very
AOI Florida
least subtropical cyclone characteristics. Dvorak estimates at the time had this system being a 40mph subtropical storm and land reports had sustained winds of 60mph and gusts up to hurricane strength. At the last NHC update before landfall, the NHC said that this low pressure system was an extratropical gale and that the organized convection had been insufficient to upgrade 93L into Subtropical Storm Rina. Multiple sources show that 93L had a sufficiently warm core for an upgrade to a subtropical storm and the definition of a subtropical cyclone has no mention of requiring organized convection. Shortly after the update 93L made landfall. There is no solid reason as to why this system did not get upgraded to Subtropical Storm Rina, however a reason may be because it was so close to landfall at the time it gained subtropical characteristics that issuing advisories would be a waste and no preparations could be done to minimize the impacts of the storm.