Eta weakens to a tropical depression over central America…but will redevelop over the western Caribbean Sea.
Discussion:
Eta continues to weaken after having passed over the high mountainous terrain over central America in the last 24 hours. It is hard to find much evidence of any low level circulation on visible satellite images and it is very possible that the low level vortex of Eta has dissipated. With that said, the remains of the tropical system will be moving back over the warm waters of the western Caribbean Sea later today where re-development is likely and support by many of the global forecast models.
Track:
Eta has turned toward the NW and this motion at a slow rate of speed is likely through the next 24 hours before a trough of low pressure that will develop along the Louisiana coast digs southeast into the central Gulf of Mexico over the weekend. This trough will result in a NE motion of Eta toward the Cayman Islands and Cuba over the weekend. By early next week this trough will dig into the southeast Gulf of Mexico and Eta will turn sharply toward the NW and even west on the northeast or northern side of the Gulf upper level trough and an usually strong high pressure ridge for this time of year over the eastern US. This track will bring Eta toward the southern FL Keys and then into the southeast Gulf of Mexico by early next week. The multi-model consensus continues to struggle with the various steering patterns and changes in those patterns over the next 5 days and the various turns in direction and forward speed of the system. The forecast track in the 72-120 hour period is of lower than average confidence and changes are likely, but a threat to the FL Keys and southern FL remains in play.
Intensity:
Eta will need to re-build its low level vortex and inner core and while water temperatures over the western Caribbean Sea are certainly warm, the upper level conditions may not be overly favorable mostly due to the upper level trough expected over the Gulf of Mexico with likely some degree of southwesterly shear over the tropical system. It is possible that Eta may eventually transition toward a sub-tropical system as it becomes increasingly entangled with the upper level trough over the Gulf of Mexico. For now NHC brings the system to a 65mph tropical storm over the FL straits early next week with some of the intensity guidance showing slightly stronger solutions that would be near hurricane intensity.
Jeff Lindner
Director Hydrologic Operations Division/Meteorologist
Harris County Flood Control District