Subtropical Storm Alberto Track Chart, Advisory #19
 


Current Location: 25.0N, 84.2W
Geographic Reference: 325 miles south of Apalachicola, FL
Movement: North-northeast at 12 mph
Max Winds: 40 mph gusting to 50 mph
Current Hurricane Severity Index: 2 out of a possible 50 points (1 size, 1 intensity)
Max Predicted Hurricane Severity Index: 5 out of a possible 50 points (2 size, 3 intensity)
Current Radius of Tropical Storm-Force Winds: 115 miles
Max Predicted Radius of Tropical Storm-Force Winds: 120 miles
Organizational Trend: Becoming better organized and transitioning into a tropical storm
Forecast Confidence: Average

Key Points

  1. There has been a significant change to the track forecast. Alberto is now forecast to move inland near Apalachicola in about 24 hours.
  2. With the track change, the chance of Alberto becoming a hurricane has decreased to 10 percent
  3. With Alberto moving faster than previously forecast, we have decreased the expected rainfall totals over the southeast United States. There is still a region that extends from the Florida Panhandle through Alabama that will receive moderate rain impacts, however.

Our Forecast
Alberto has again accelerated to the north-northeast during the overnight hours. The surface center appears to be a bit to the south of a well-defined mid level center. That said, there is a chance for the centers to become aligned during the day. This, along with the latest model guidance, which has shifted dramatically to the north and east overnight, is the reason for the major track change. Alberto is now expected to move fairly quickly to the north throughout the day today. We still expect the north-northwest bend to occur, but not until Alberto is nearly onshore. The changes to the forecast track mean that landfall is now forecast to occur in about 24 hours around Apalachicola instead of tomorrow afternoon near Pensacola. It should be stated that if the northwest turn occurs a little sooner than forecast, landfall could occur farther west, perhaps near Ft. Walton. The angle of the coastline and the direction in which the storm is approaching is why there is a wide range of landfall possibilities. After landfall, we expect that Alberto will move north-northwest into Alabama and then turn back to the north, taking the remnants through Tennessee.

Alberto appears better organized this morning. However, as stated, the surface center is south of the mid level center. Once these become aligned later today, intensification will occur. The forecast is still for winds to reach 60 mph at landfall. However, the fact that there will be about 12 hours less over water means that the chance of Alberto becoming a hurricane has decreased from 25 percent to 10 percent.

With Alberto moving a bit faster than we were previously forecasting, we have lowered the peak rainfall amounts. In addition, the area that is expected to receive the greatest impacts from rain has been shifted to the east.

Expected Impacts Offshore
Mississippi Canyon/Viosca Knoll/Mobile – There is now only a very slight risk of tropical storm conditions in this area.

Expected Impacts Onshore
Florida Peninsula – Heavy rainfall is expected to occur for much of the day. This will likely lead to periods of street flooding, resulting in travel delays. Winds may briefly reach tropical storm force around Tampa Bay, causing power outages.

Florida Panhandle through Southern Alabama – Widespread power outages are expected near where Alberto makes landfall. Major travel delays are expected for the area that receives the heaviest rains.

Our next advisory will be issued by 9 AM CDT

Meteorologist: Derek Ortt / George Harvey


Forecast Confidence:   Average Hurricane Severity Index
Fcst Hour Valid Lat. Lon. Max Sustained Winds Max Gusts Category Size Intensity Total
0 3AM CDT Sun May 27 25.00N 84.20W 40 mph 50 mph Subtropical Storm 1 1 2
12 3PM CDT Sun May 27 27.50N 84.50W 50 mph 65 mph Tropical Storm 1 2 3
24 3AM CDT Mon May 28 29.50N 85.00W 60 mph 70 mph Tropical Storm 2 3 5
36 3PM CDT Mon May 28 31.00N 86.00W 40 mph 50 mph Tropical Storm 1 1 2
48 3AM CDT Tue May 29 32.30N 86.70W 30 mph 35 mph Tropical Depression 0 0 0
60 3PM CDT Tue May 29 34.50N 86.70W 25 mph 30 mph Remnant Low 0 0 0
72 3AM CDT Wed May 30 37.00N 86.50W 15 mph 25 mph Remnant Low 0 0 0

The yellow cone represents track error from the previous five hurricane seasons. Over the past five hurricane seasons, the center of the storm tracked within the yellow cone 75% of the time. The cone does not represent the forecast uncertainty in the current advisory for this storm. In addition, hurricane-force winds, very high tides, large waves, and heavy rainfall can often extend well outside the yellow cone.