Impacts on Central Alabama look to be just scattered rain chances Saturday with the heaviest rain/wind threat closer to the coast.
Although the convection associated with the disturbance has increased during the past few hours, there is no evidence that a well-defined center has formed yet. One can observe several swirls of low clouds rotating within a larger gyre. Most of the global models forecast that the system will become better organized later today, and given the current trend, NHC forecasts that a tropical or most likely a subtropical cyclone will form later this morning. A reconnaissance plane will investigate the disturbance in a few hours.
The disturbance is located to the east of an upper trough which is digging along the western Gulf of Mexico, and the upper-level diffluence caused by the trough should induce some strengthening during the next 24 hours or so before the system moves inland. However, the simulated convection by the GFS and the ECMWF models resembles a comma-shape pattern which is characteristic of a subtropical cyclone. After landfall, the cyclone is expected to become extratropical and gradually weaken while it moves northeastward near the southeast U.S. coast. By day 5, the low is forecast to be absorbed by a front over the western Atlantic.
Since the center is not well defined, the initial motion is highly uncertain. The best estimate is toward the northeast or 045 degrees at 12 kt. The system should accelerate later today and continue toward the northeast embedded within the flow ahead of the trough. Track models are in remarkably good agreement, and the NHC forecast is in the middle of the tight guidance envelope.
Regardless of the exact evolution of the system, portions of the northern coast of the Gulf of Mexico will experience strong winds, locally heavy rains, and storm surge Friday and Saturday. Similar impacts are expected across portions of the Atlantic coast of the southeastern United States Saturday and Sunday.
1. There is a danger of life-threatening storm surge inundation of up to 5 feet above ground level beginning today along the Florida Gulf Coast from Indian Pass to Clearwater, where a Storm Surge Warning is in effect. Residents in these areas should follow advice given by local officials.
2. Tropical storm force winds are likely by later today along portions of the central and eastern Gulf Coast, where tropical storm warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center.
3. Isolated flash flooding is possible along the central and eastern Gulf Coast and southeastern United States coast from today through Saturday night. Since soils across the southeast are dry, the risk of flash flooding will be confined to the immediate coast where heavier rainfall is possible.
4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices, since the system is expected to lose any tropical characteristics after it moves inland along the Gulf Coast.