As of Thursday morning September 26, Hurricane Helene is a strong category 2 hurricane with sustained winds of 110 mph. Helene is forecasted to strengthen into a category 3 hurricane with winds up to 129 mph before impacting the Florida panhandle near Panacea Thursday evening. Helene will bring widespread damages to Florida and other Southeastern states on Thursday and into the weekend. The main threats are strong winds, storm surge, and heavy rain with flooding.

Let's go over the timeline for Helene and the anticipated impacts.

Thursday, September 26

Hurricane Helene is located in the Gulf of Mexico and is undergoing rapid intensification. This rapid intensification is due to very warm waters in the Gulf of Mexico (85-88 degrees Fahrenheit), which is expected to strengthen Helene into a category 3 hurricane before impacting the Florida panhandle. 

The forecast has Helene strengthening into a category 3 hurricane, but there is still a small chance Helene could reach a category 4 hurricane as conditions favor rapid intensification until landfall near Panacea, Florida. 

Sea surface temperatures in the Gulf of Mexico as of Tuesday, September 24, 2024. These are well above normal and leading to the rapid intensification of Helene!

Rapid intensification is when a storm strengthens very quickly (< 24 hrs) with stronger winds and grows in size.

• Category 1 -> 74-95 mph, 64-82 kt, 119-153 km/h
• Category 2 -> 96-110 mph, 83-95 kt, 154-177 km/h
• Category 3 -> 111-129 mph, 96-112 kt, 178-208 km/h
• Category 4 -> 130-156 mph, 113-136 kt, 209-251 km/h
• Category 5 -> 157 mph or higher, 137 kt or higher, 252 km/h or higher

Learn more -> Tropical Cyclones, Explained

Strong Winds: Helene is rapidly intensifying into a major hurricane and growing in size. This means that strong winds will extend far away from Helene's center, which will affect areas far away from the direct path of the hurricane.

Winds in the center of the path will affect through Tallahassee, Florida, and into southern Georgia with winds over 110 mph likely.

• Winds could be as strong as 129 mph or greater at the center of the direct path along the coast if rapid strengthening continues

Winds will extend from 74-110 mph outside of the direct path and through central Georgia and along the Alabama border. The wind swath of 39-57 mph will extend far way through all of Florida into Alabama, northern Georgia, Tennessee, South Carolina, and southern North Carolina.

Storm Surge: This is one of the most dangerous aspects of Helene but is also the most localized to areas along the Florida panhandle. Storm surges at the direct impact area and to the east of this will see 15-20 feet of sea-level rise!

Storm surges will rapidly decrease outside of the 15-20 feet near the landfall and eastern locations. Storm surges of 3-10+ feet will cover large swaths of the Florida coast and affect coastal towns and roadways.

Heavy Rain: This will be the widest felt effect from Helene and cover the Southeast US into the Central and Eastern US. As of Thursday morning, heavy rain has affected many areas due to thunderstorms ahead of Helene that already brought flooding on Wednesday, September 25. These storms will continue on Thursday and tap into Helene's tropical moisture, causing heavy downpours with flooding.

On Thursday, a narrow tongue of moisture and storms will move from Florida along the Alabama-Georgia border and into the Smoky Mountains in North Carolina and Tennessee. This area of rain will bring 2-5+ inches. 

An additional threat associated with the heavy rain will be tornadoes. Tornadoes often occur once tropical cyclones make landfall because of increased wind shear. Increased wind shear causes tropical cyclones to weaken but can also cause tornadoes. Tornadoes form because of increased wind speed and direction changes with height. This creates a spin in the atmosphere, which allows tornadoes to develop.

Below is a look at the tornado probability on Thursday, September 26 with coastal Georgia and South Carolina seeing the greatest threat.

Friday, September 27

Helene will move quickly into the Southeast on Friday and reach Tenessee by Friday afternoon. Helene will quickly weaken into a tropical storm with sustained winds of 39-73 mph during this time frame. Helene will still have a large wind swath with 20-40 mph winds in nearby states of North Carolina, Kentucky, Alabama, and Mississippi.

The greatest threat with forecasted tropical storm Helene on Friday will be heavy rain, flash flooding, and tornadoes. Heavy rain is expected across the Southeast with 2-5+ inches covering a large area. This will be on top of many locations that saw 2-5+ inches of rain on Thursday.

The highest rain totals and greatest concern for flooding will be in the Smoky Mountains. Heavy rain with orographic lift and steep terrain will cause dangerous conditions in these areas.

Additionally, tornadoes will continue to be a threat throughout these areas as wind shear from the tropical storm causes brief tornadoes to occur. The greatest threat for tornadoes will be on the eastern side of the Smoky Mountains in North Carolina and South Carolina.

Saturday, September 28 and Sunday, September 29

Helene will become semi-stationary this weekend over the Lower Ohio River Valley in Kentucky and Tennessee. Helene will weaken into a post-tropical cyclone and primarily bring moderate rain. Winds will continue to be gusty at 20-40+ mph and primarily occur in thunderstorms.

As the storm remains semi-stationary, it will weaken but still bring moderate rain. Additional rainfall totals on Saturday and Sunday will be 0.5-2 inches.

Not all effects from Helene will be damaging and this rain will be much needed across the Ohio River Valley. There are currently moderate to exceptional drought conditions and this beneficial rain is expected to help improve the drought situation.

Thanks for reading and stay safe!

Zach Butler