The hurricane Isaías was downgraded to category 1 in advisory number 14 from the National Hurricane Center (NHC), issued at 11:00 p.m. Miami time this Friday, with maximum sustained winds of 90 mph (150 km/h) and gusts up to 105 knots, as it moved over northwestern Florida toward Alabama.
The weakening occurred hours after the system made landfall near Destin, Florida as a category 2 hurricane, a previously recorded event. According to the technical discussion of advisory 14, the strong vertical wind shear degraded the cyclone's structure after it moved inland, prompting the NHC to lower the initial intensity from 90 to 80 knots in this bulletin.
The drop in category does not equate to the end of danger.
The NHC warned that "the sustained surface winds associated with Isaías will quickly weaken now that the system is inland, but harmful gusts are expected well inland throughout Saturday, especially in higher elevation areas."
In advisory 14, the center of the system was located about 75 km northeast of Pensacola and 100 km northwest of Panama City, moving north at 20 mph (31 km/h).
The NHC forecasts that Isaías will become a post-tropical system within the next 12 hours as it moves northward across Alabama, but clarified that this transition will not put an end to the destructive gusts inland.
To understand the current intensity: the Saffir-Simpson scale classifies category 1 hurricanes with winds of 74 to 95 mph, enough to cause widespread power outages and turn loose objects into projectiles.
With this notice, the NHC canceled several coastal advisories: the Hurricane Warning west of the Mississippi/Alabama border, the Tropical Storm Warning west of Ocean Springs (Mississippi), the Storm Surge Warning west of Dauphin Island (Alabama), and the Storm Surge Watch east of the Suwannee River (Florida).
However, alerts of greater severity still remain in effect.
The Hurricane Storm Surge Warning remains active from Dauphin Island to the Suwannee River, an area classified by the NHC as a "life-threatening situation."
There is also a Hurricane Warning in effect from the Mississippi/Alabama border to the county line between Bay and Gulf in Florida, and a Tropical Storm Warning from that line to the Aucilla River.
The surge could flood areas that are normally dry with heights ranging from three to five feet (0.9 to 1.5 meters) from Dauphin Island to the Aucilla River, and from two to four feet in Mobile Bay and between the Aucilla River and the Suwannee, as long as the peak surge coincides with high tide.
Among the other active risks, the NHC forecasts rainfall of four to eight inches in southern Alabama, the Florida Panhandle, and the Big Bend, with localized totals of up to 15 inches in some bands; a risk of tornadoes overnight in the Panhandle and northern Florida extending into southern Georgia, which will continue into Georgia and the Carolinas on Saturday; and the possibility of landslides in the Southern Appalachians.
The NHC forecast indicates that the system will be post-tropical over Alabama by noon UTC on Saturday, with winds of 60 mph, and it will dissipate by Monday, October 12, at 12:00 UTC.
The NHC summarized the key message for areas still under Hurricane Warning: "Residents in these areas should have a safe shelter to weather the storm and prepare for extended power outages."
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