Subtropical Storm Alberto is slightly better organized today. The original low-level circulation over the Northwestern Caribbean has dissipated and a new, well-defined circulation has developed northwest of Cuba. Alberto is gradually acquiring tropical characteristics, and should transition into a fully tropical storm by late Sunday. Most of the model guidance has shifted slightly east today, and it appears as if Alberto will make landfall somewhere between Mobile, Alabama and Pensacola, Florida sometime on Monday. It appears less likely today that Alberto will become a minimal hurricane before landfall, but this possibility cannot be ruled out entirely just yet. I personally think a high-end tropical storm landfall is most likely.

As of 2:00 p.m. EDT Saturday, Subtropical Storm Alberto was centered near 22.8°N 85.2°W and was moving northward at about 13 mph. Maximum sustained winds were 35 knots (40 mph), with an estimated minimum pressure of 999 mb – a drop of 5 mb since this morning as the new center developed. Another Air Force Hurricane Hunter aircraft will investigate Alberto this evening, and will provide a better estimate of its structure and intensity. Additional center reformations cannot be ruled out over the next day or so. Environmental conditions are becoming more conducive for development. Based on the 18z Saturday SHIPS guidance, wind shear is currently about 20 kt but is expected to decrease to less than 10 kt on Sunday afternoon. Normally, wind shear this low would favor rapid intensification. However, Alberto will be moving over cooler waters of about 26.5°C (79.7°F) and will be moving into a drier environment with mid-level relative humidity values less than 60 percent. With a more eastward track now predicted, Alberto will be moving over cooler waters than previously anticipated. The 12z GFS and ECMWF models both predicted that Alberto would make landfall along the western Florida panhandle as a strong tropical storm on Monday afternoon, before moving quickly northward towards the Midwestern United States. Alberto should lose tropical characteristics by next Thursday.

The primary threat with Alberto remains heavy rain, especially to the east of the center. The heaviest rainfall totals will likely occur just east of the landfall location. Alberto is likely to produce heavy rainfall throughout the Southeastern United States, even far to the east of the center of circulation. Tropical storm force winds are possible along the western Florida peninsula, the Florida Panhandle, eastern Louisiana, and the coasts of Alabama and Mississippi. A Storm Surge Watch is in effect for Crystal River to the Mouth of the Mississippi River. A Tropical Storm Warning is in effect for the Cuban Province of Pinar del Rio, and Dry Tortugas. A Tropical Storm Watch is in effect for Boca Grande to Anclote River, Aucilla River to Grand Isle, and Lake Pontchartrain and Lake Maurepas.

I will be back with another update on Alberto tomorrow.