Subtropical Storm Alberto Track Chart, Advisory #17

Current Location: 23.4N, 85.1W
Geographic Reference: 110 miles north of the western tip of Cuba
Movement: North at 14 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: 125 miles
Max Predicted Radius of Tropical Storm-Force Winds: 125 miles
Organizational Trend: Very slowly becoming better-organized
Forecast Confidence: Average

Key Points
The center of Alberto is reforming farther north, which has several implications:

  1. Landfall on the Gulf Coast is now projected to be Monday afternoon vs. evening.
  2. Greater shear up to landfall may restrict its intensification somewhat.
  3. Faster movement increases the chance that landfall will be farther east along the Gulf Coast.
  4. Alberto may be transitioning to a tropical storm over the next 12-18 hours.

Our Forecast
A reconnaissance plane has been investigating Alberto for the past 3-4 hours. During that time, the center which was located south of western Cuba dissipated, and a new center formed about 90 miles north of western Cuba, closer to some heavier squalls. With the new center already located where it was predicted to be this evening, our track has been adjusted to take the center inland about 4-5 hours earlier on Monday. Though the plane was not able to confirm sustained 40 mph winds, with the center redeveloping closer to the heavy squalls, we think that Alberto’s winds may be increasing over the next 6-12 hours as it begins to transition to a tropical storm.

The northward center reformation and earlier landfall means that Alberto will take less of a northwesterly track on Sunday. We have adjusted the landfall point eastward to east of Mobile Bay. It is possible that the track may need to be adjusted even farther east in future advisories if the current trends continue. This eastward adjustment in the track reduces the risk to the Mississippi coast somewhat, and it significantly reduces the risk of heavy rain for the New Orleans area.

Finally, less of a northwest track on Sunday means that the wind shear may be a little stronger. This would reduce the potential intensity. We have lowered the predicted max sustained winds from 65 mph to 60 mph in this advisory.

Expected Impacts Offshore
Mississippi Canyon/Viosca Knoll/Mobile – The eastward track adjustment reduces, but does not eliminate, the risk of tropical storm conditions in Mississippi Canyon north through the Viosca Knoll and Mobile blocks.

Expected Impacts Onshore
Florida Peninsula – Rain bands capable of producing heavy rainfall and gusty winds are already impacting the coast from Ft. Myers to Tampa. These squalls may result in brief street flooding and isolated power outages.

Florida Panhandle through Southern Alabama – Heavy showers and thunderstorms will occur from Sunday through Tuesday, resulting in widespread travel issues. Wind gusts in squalls may produce scattered power outages along the immediate coast of Alabama and Florida. Widespread power outages are likely near where the center makes landfall.

Mississippi Coast – Alberto’s strongest wind and heaviest squalls may pass to your east on Monday. Of course, any track adjustment back to the west may put the Mississippi coast back into the heavier squalls and stronger winds.

Our next advisory will be issued by 9PM CDT

Meteorologist: Chris Hebert

Forecast Confidence:   Average Hurricane Severity Index
Fcst Hour Valid Lat. Lon. Max Sustained Winds Max Gusts Category Size Intensity Total
0 3PM CDT Sat May 26 23.40N 85.10W 40 mph 50 mph Subtropical Storm 1 1 2
12 3AM CDT Sun May 27 25.90N 84.90W 40 mph 50 mph Subtropical Storm 1 1 2
24 3PM CDT Sun May 27 27.80N 85.70W 45 mph 60 mph Subtropical Storm 1 2 3
36 3AM CDT Mon May 28 28.90N 86.70W 50 mph 65 mph Tropical Storm 1 2 3
48 3PM CDT Mon May 28 30.20N 87.50W 60 mph 70 mph Tropical Storm 2 3 5
60 3AM CDT Tue May 29 31.70N 87.90W 40 mph 50 mph Tropical Storm 1 1 2
72 3PM CDT Tue May 29 34.10N 87.80W 25 mph 35 mph Remnant Low 0 0 0
84 3AM CDT Wed May 30 36.90N 87.70W 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.