Helene reaches hurricane strength; landfall expected in Florida Thursday

Per the 11 a.m. EDT update from the National Hurricane Center, Helene has become a category-one hurricane with maximum sustained winds near 130 km/h. The hurricane force winds were confirmed by Air Force Reserve and NOAA Hurricane Hunter aircraft. The storm is positioned 135 km to the northeast of Cozumel, Mexico as it moves into the Gulf of Mexico.

Rapid strengthening to a major hurricane

The storm is moving into very favourable conditions for further intensification. Sea surface temperatures ahead of the hurricane are near 30 degrees and the wind environment over the Gulf of Mexico isn’t expected to be strong enough to disrupt the storm. Hurricanes need sea surface temperatures of just over 27 degrees to fuel them.

Helene is forecast to become a category-three hurricane Thursday morning with maximum sustained winds near 195 km/h. The strongest winds near the centre of the storm are then expected to reach 205 km/h just before landfall, which is projected to be on the Florida panhandle Thursday night. Once inland, the storm will eventually weaken to a tropical storm and then post-tropical area of low pressure.

Category-three hurricanes are capable of extensive structural damage to buildings near the landfall location both as a result of the extreme wind and storm surge. They can uproot a large number of trees and the damage done to utilities can take several weeks to recover from.

The forecast intensity and cone for the storm from the late Wednesday morning update of the National Hurricane Center. (Source: CTV News Atlantic)

Hurricane warnings

Hurricane Warnings have been issued in Florida from just north of Tampa to Apalachicola on the Florida Panhandle. The Hurricane Warnings also extend into southern Georgia. Much of the remainder of Florida is under a Tropical Storm Warning.

Hurricane and tropical storm warnings are issued when those conditions are expected within 36 hours.

A Tropical Storm Watch extends across the state of Georgia and into parts of the Carolinas as well as eastern Tennessee. Tropical storm watches are issued for areas where tropical storm conditions are possible within 48 hours.

Residents under warnings are being advised to complete preparations by or before early Thursday.

Hurricane and Tropical Storm Warnings issued by the National Hurricane Center and National Weather Service. (Source: CTV News Atlantic)

Life-threatening storm surge and rain

The worst of the storm surge is expected to be along the Florida Big Bend coastline. The National Hurricane Center cautions “there is a danger of life-threatening storm surge” and the highest inundation of water may be greater than 10 feet or three metres.

Torrential rain is expected to impact a larger area of the southeastern United States. Indications are for a risk of rain amounts ranging from 100-to-300 mm beginning on the Florida Panhandle and extending north through the state of Georgia and into parts of the Carolinas and Tennessee. Eastern areas of the state of Alabama are also at risk of rain totals exceeding 100 mm. That amount of rain will bring a risk of flash and urban flooding.

A swath of flooding rain is expected through western Florida, Georgia, and for parts of Alabama, the Carolinas, and Tennessee. (Source: CTV News Atlantic)

Bands of thunderstorms brought in by the hurricane are also likely to produce isolated, brief tornadoes.