Current Location: 14.6N, 49.3W
Geographic Reference: 775 miles east of Martinique
Movement: West at 14 mph
Max Winds: 70 mph gusting to 85 mph
Current Hurricane Severity Index: 6 out of a possible 50 points (2 size, 4 intensity)
Max Predicted Hurricane Severity Index: 8 out of a possible 50 points (3 size, 5 intensity)
Current Radius of Tropical Storm-Force Winds: 60 miles
Max Predicted Radius of Tropical Storm-Force Winds: 70 miles
Organizational Trend: Steady
Forecast Confidence: Average
Key Points
1. Isaac is predicted to strike the central Lesser Antilles as a strong tropical storm Thursday morning.
2. Weakening and dissipation are forecast to occur in the Caribbean due to strong wind shear.
3. Other than slightly decreasing the radius of tropical storm force winds, we have not made any changes to the forecast.
Our Forecast
Isaac may become a hurricane again over the next 24 hours. However, Isaac will weaken to a tropical storm before reaching the Caribbean on Thursday as it encounters increasing wind shear. It will still be capable of producing wind gusts to up to 80 mph to 85 mph in any intense squalls on Thursday as it moves across the central portion of the Lesser Antilles.
We have not made any significant changes in the forecast track. The track remains close to the middle of most of the ensemble model members. Once Isaac moves past the Lesser Antilles on Thursday afternoon, we expect it to slowly weaken to a remnant low this weekend as it passes to the south of Haiti and Jamaica. Most model guidance overnight continues to indicate the dissipation of Isaac from wind shear over the Caribbean this weekend. We continue to think that this is likely to happen.
Expected impacts on Land
Central Lesser Antilles: Widespread power outages are expected within about 45 miles of the center, along with moderate structural damage. Flooding and mudslides are likely to cause some damage and travel delays.
Puerto Rico : At this time, most of the rain and all of the wind associated with Isaac are expected to pass the island to the south. However, Isaac could track close enough to the island to bring an increased chance of showers and thunderstorms on Friday.
Our next advisory will be issued by 4 PM AST / 3 PM CDT.
Meteorologist: Cameron Self
| Forecast Confidence: Average | Hurricane Severity Index | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Fcst Hour | Valid | Lat. | Lon. | Max Sustained Winds | Max Gusts | Category | Size | Intensity | Total |
| 0 | 9AM CDT Tue Sep 11 | 14.60N | 49.30W | 70 mph | 85 mph | Tropical Storm | 2 | 4 | 6 |
| 24 | 9AM CDT Wed Sep 12 | 14.90N | 55.30W | 75 mph | 90 mph | Category 1 | 3 | 5 | 8 |
| 36 | 9PM CDT Wed Sep 12 | 15.20N | 58.30W | 70 mph | 85 mph | Tropical Storm | 2 | 4 | 6 |
| 48 | 9AM CDT Thu Sep 13 | 15.50N | 61.30W | 70 mph | 85 mph | Tropical Storm | 2 | 4 | 6 |
| 60 | 9PM CDT Thu Sep 13 | 15.60N | 64.30W | 65 mph | 80 mph | Tropical Storm | 2 | 3 | 5 |
| 72 | 9AM CDT Fri Sep 14 | 15.50N | 67.60W | 50 mph | 70 mph | Tropical Storm | 1 | 2 | 3 |
| 84 | 9PM CDT Fri Sep 14 | 15.30N | 70.60W | 45 mph | 60 mph | Tropical Storm | 1 | 2 | 3 |
| 96 | 9AM CDT Sat Sep 15 | 15.20N | 73.00W | 40 mph | 50 mph | Tropical Storm | 1 | 1 | 2 |
| 108 | 9PM CDT Sat Sep 15 | 15.20N | 75.10W | 35 mph | 45 mph | Tropical Depression | 0 | 1 | 1 |
| 120 | 9AM CDT Sun Sep 16 | 15.30N | 77.10W | 30 mph | 40 mph | Remnant Low | 0 | 0 | 0 |
| 132 | 9PM CDT Sun Sep 16 | 15.60N | 79.00W | 30 mph | 40 mph | Remnant Low | 0 | 0 | 0 |
| 144 | 9AM CDT Mon Sep 17 | 16.00N | 81.00W | 30 mph | 35 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.
