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Tropical Depression Nineteen forms off the southeastern coast of Florida

Posted at 5:35 PM, Sep 11, 2020

From the National Hurricane Center:

"It is uncertain whether the large burst of convection over the center will continue and cause the depression to become a tropical storm before reaching Florida. However, since it is only a 5 kt increase from the current intensity, it is possible that tropical storm conditions could still occur along the southeast Florida coast late tonight, and a tropical storm watch has been issued.

Otherwise, after the system reaches the eastern Gulf of Mexico, steady intensification is expected through the weekend due to expected light wind shear and very warm water. Some increase in shear could occur over the northern Gulf of Mexico but that is uncertain at this time. The first forecast will stay conservative and only show a peak intensity of 60 kt in 3 to 4 days, but do not be surprised if that is revised upward on later forecasts once other models better initialize the depression.

An uncertain estimate of the initial motion is 285/7. Strong ridging over the southeastern United States is expected to steer the cyclone to the west-northwest then northwest as a mid-latitude trough erodes the western side of the ridge over the weekend. The forecast gets tricky after that because the bulk of the guidance suggests the trough isn't deep enough to recurve the system, and instead it gets left behind, moving slowly westward early next week due to weak ridging over the southern Plains.

The NHC forecast is near the corrected-consensus guidance. The uncertainty in the track forecast is much larger than normal after 48 hours, as small changes in the forecast steering flow could result in this system moving over the northern Gulf Coast faster and to the northeast of what is shown here. As a result, the risk of seeing direct impacts from this system extends well outside the cone of uncertainty, even more so than usual in this case.

KEY MESSAGES:

1. Heavy rainfall is expected to produce isolated flash flooding over portions of central and southern Florida and prolong existing minor river flooding in the Tampa Bay area.

2. Tropical storm conditions are possible tonight along the southeast Florida coast where a Tropical Storm Watch is in effect.

3. The system is forecast to strengthen to near hurricane intensity by early next week as it moves across the northeastern Gulf of Mexico. Dangerous impacts from storm surge, wind, and heavy rainfall will be possible along the Gulf Coast from the Florida Panhandle to southeastern Louisiana this weekend and early next week. Residents in these areas should monitor the progress of this system and updates to the forecast, as Storm Surge, Tropical Storm or Hurricane watches could be issued later tonight and Saturday."

Here is a look at estimated rainfall totals for us here in Acadiana over the next week. At this time, it does appear that the heaviest of the rainfall and worst of the impacts will stay east of Acadiana, but of course that can still change.

Continue to stay with the KATC storm team for the very latest.