Hurricane Helene has shortly intensified into an enormous Class 4 storm, with hurricane-force winds extending as much as 60 miles outward from the attention. Forecasters warn that Helene — which has wind speeds of close to 120 miles per hour — could possibly be lethal for these residing in coastal Florida, the place it’s anticipated to make landfall this night.
The Nationwide Hurricane Heart predicts storm surge as excessive as 20 toes in some components of Florida’s Massive Bend, a area between the panhandle and the peninsula. Storm surge, which describes an increase in sea degree, is essentially the most harmful a part of tropical storms and has a lethal monitor document: In 2022, storm surge killed greater than 40 individuals throughout Hurricane Ian. The storm can be anticipated to inundate inland areas throughout a lot of the southeastern US with rain, dumping a foot or extra in components of southern Appalachia.
“This rainfall will doubtless end in catastrophic and doubtlessly life-threatening flash and concrete flooding,” the Nationwide Hurricane Heart stated early Thursday afternoon.
Helene may additionally disrupt a part of the epic monarch butterfly migration, which generally passes by the Massive Bend’s St. Marks Nationwide Wildlife Refuge in early October.
Helene is the eighth named storm in what has up to now amounted to a considerably puzzling hurricane season. It began with a bang — June’s Hurricane Beryl turned the earliest Class 5 storm on document — after which a lot of August and September was unexpectedly quiet.
Many meteorologists, although, have been warning to not be fooled by this late-summer lull.
“Having multi-week intervals of quiet after which multi-week intervals of exercise may be very regular all through a hurricane season,” Brian McNoldy, a climatologist on the College of Miami, instructed me earlier this month. “I undoubtedly wouldn’t learn an excessive amount of into it.”
Plus, McNoldy stated, the ocean within the Gulf of Mexico has been — and nonetheless is — exceptionally scorching, and scorching water fuels hurricanes. Ocean warmth content material, a measure of how a lot warmth vitality the ocean shops, is at a document excessive for this time of 12 months.
Check out the chart beneath. The crimson line is 2024 and the blue line is the typical during the last decade.
This document ocean warmth is a transparent cause why Hurricane Helene — which has been touring by the Gulf on its approach to Florida — has intensified so shortly. Put merely, hotter water evaporates extra readily, and rising columns of heat, moist air from that evaporation are finally what drive hurricanes and their speedy intensification.
“The sea floor temperature and the ocean warmth content material are each document excessive within the Gulf,” McNoldy, who produced the chart above, instructed me. “That warmth on the floor and obtainable by a depth will give Helene all of the gas it must quickly intensify at present and into tomorrow.”
The document Gulf temperatures are only one sign of a extra widespread bout of warming throughout the North Atlantic that ramped up final 12 months.
It’s not fully clear what’s inflicting this warming, although scientists suspect a mixture of things together with local weather change — which raises the baseline ocean temperature — in addition to lingering results of El Niño, pure local weather variability, and maybe even a volcanic eruption.
“That is out of bounds from the sorts of variability that we’ve seen in [at least] the final 75 years or so,” Ben Kirtman, director of the Cooperative Institute for Marine and Atmospheric Research, a joint initiative of the College of Miami and the Nationwide Oceanic and Atmospheric Administration (NOAA), instructed Vox in August. “That may be scary stuff.”
Replace, September 26, 6:50 pm ET: This story, initially revealed September 25, has been up to date with new info as Hurricane Helene approaches the Florida coast.