re: Sally - Moving towards Georgia - Potential for Significant Flooding

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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.

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