Weekend/Tropical Outlook: September 27-30, 2024

Once the rain ends, we’ve got some rather nice weather coming up for the weekend. Meanwhile, the tropics are getting active again with Major Hurricane Helene heading for the Florida Panhandle, Tropical Storm Isaac in the North Atlantic, and potentially another system this weekend.

Some much-needed rainfall is expected across the region tonight. Image provided by WeatherBell.

A cold front will cross the region tonight, taking the rain with it by morning as it moves offshore. High pressure will then build in, and remain in control through Monday, keeping us dry and mild, but don’t expect bright sunshine the entire time. We’ll have some slow clearing behind the front on Friday, especially near the South Coast and the Cape. After that, some high-level moisture from Hurricane Helene and its remnants (more on that in a minute) will stream up here. This will result in filtered sunshine for Saturday and likely part of Sunday too. We’ll also have northeast winds around the high pressure area to our north bringing in some clouds at times from the Atlantic. Monday will probably feature the most sunshine, but there will still be some clouds around.

The tropics are getting active again with both Hurricane Helene and Tropical Storm Isaac. Image provided by the Canadian Hurricane Centre.

Hurricane Helene continues to strength as it moves across the eastern Gulf of Mexico. As of 4pm EDT, Helene was centered about 145 miles west-southwest of Tampa, Florida, moving toward the north-northeast at 21 mph. Maximum sustained winds were near 120 mph, making Helene at Category 3 Hurricane. Helene’s future is fairly simple at this point. It will continue north-northeastward, with a little more strengthening likely, then it will make landfall in the Florida Big Bend area tonight. This is a sparsely populated region of Florida, which is the only “good” news we have with this storm. A storm surge of 15-20 feet is likely near and to the right of where the center makes landfall. Helene is a very large storm, with tropical storm force winds up to 350 miles from the center of the storm. With this in mind, strong winds are likely well inland after landfall, likely into southern or central Georgia, with widespread wind damage expected.

Hurricane Helene is marching toward the Florida Big Bend. Loop provided by the College of DuPage.

The biggest threat will be heavy rain well inland. Much of the Southeast has already received 3-6 inches of rain in the past day or two from a frontal system, and Helene will add another 5-10 inches or more to that. While this region has been in a drought and needs rainfall, too much rainfall doesn’t help as much and creates widespread flooding. An upper-level low pressure system over the Mississippi Valley will capture the remains of Helene this weekend, slowing it down across the Tennessee Valley before it finally dissipates, bringing even more rain to this region as well.

Helene will produce heavy rain over a very large area over the next few days. Image provided by the National Hurricane Center.

Helene isn’t the only show in town though. We also have Tropical Storm Isaac, centered about 820 miles east-northeast of Bermuda as of 11am EDT, moving toward the east at 12 mph. Maximum sustained winds are near 50 mph. Isaac is expected to steadily strengthen, and could become a hurricane this weekend. It should continue eastward or east-northeastward over the open waters of the North Atlantic, becoming extratropical early next week, at which point it could be heading towards Europe.

Tropical Storm Isaac is gradually organizing in the North Atlantic. Loop provided by NOAA.

But wait, there’s more! Another area of low pressure in the central Atlantic, several hundred miles west of the Cabo Verde Islands continues to get better organized this afternoon, and conditions are favorable for it to become a tropical depression later today or Friday. The system could become a tropical storm over the weekend, but should eventually turn more toward the north and head out into the open Atlantic without impacting any land areas for the next week or so.

The next system should head out to sea without impacting land. Loop provided by Tomer Burg.

Thursday night: Cloudy with rain gradually ending, some clearing late at night, mainly from the Merrimack Valley northward, some patchy fog may also develop. Low 54-61.

Friday: A few lingering showers early across Cape Cod and the South Coast, otherwise, skies become mostly sunny in the morning, then high clouds stream back in during the afternoon. High 69-76.

Friday night: Partly to mostly cloudy. Low 51-58.

Saturday: Sunshine filtered through high clouds. High 66-73.

Saturday night: Partly to mostly cloudy. Low 50-57.

Sunday: A mix of sun and clouds. High 64-71.

Sunday night: Partly cloudy. Low 49-56.

Monday: Partly sunny. High 66-73.