From Dr. Jeff Masters' Blog:
Posted by: JeffMasters, 9:38 AM EDT on September 20, 2007
This second low pressure system was identified as "93L" by NHC beginning at 2 pm EDT yesterday. However, now that the low has weakened crossing the Florida Peninsula, the "93L" designation has been taken away from it, and attached to the upper level low pressure system in the Gulf of Mexico.
Recent Satellite loops and the Tampa Bay long range radar show that this non-tropical low pressure system is beginning to get more organized and is acquiring tropical characteristics. Substantial pressure falls are occurring at the surface underneath the upper level low, and this system is on its way to becoming a subtropical depression. A surface low pressure system vertically aligned with a cold-cored upper level low will usually take two or more days to make the transition to a warm-cored tropical storm. Rapid intensification cannot occur until the system is fully warm-core. Since landfall is expected Saturday between the Florida Panhandle and Southeast Louisiana, 93L probably does not have time to become fully tropical. If 93L makes landfall Saturday, it should not have winds stronger than about 55 mph. The GFDL, HWRF, and SHIPS intensity models all keep 93L's winds below 55 mph. If the storm spends an extra day over water and makes it to Texas, as the ECMWF model predicts, 93L could become fully tropical and make landfall as a strong tropical storm with 60-70 mph winds. However, there is plenty of dry air in the environment, and I don't think the storm will be able to intensify to a strong tropical storm. The primary threat from 93L will be heavy rain, and the northern Gulf Coast from the Florida Panhandle to Texas border can expect a soaking from this system.


