Tropical Atlantic Goes Dormant as Hurricane Season Winds Down

No new development expected for the foreseeable future with only 3 weeks left in the hurricane season

Author’s note: Today will be the last routine issuance of the daily Eye on the Tropics newsletter for the 2023 hurricane season pending any unforeseen U.S. threats. A hearty thank-you to our growing list of subscribers for your readership and support. We’ll resume the daily tropical newsletter in June 2024.

With the Caribbean clearing out in the wake of stormy Invest 97L last week, it appears the tropical Atlantic is headed on hiatus, or perhaps even into hibernation until next hurricane season.

While the Atlantic hurricane season isn’t officially over until the end of November, the season may already be behind us, especially for South Florida and the U.S. As we detailed in newsletters last week, storm-busting wind shear is cranking up throughout the tropical Atlantic and will only strengthen as the jet stream migrates south for the winter. There’s no let-up in sight for the blistering upper-level winds around U.S. waters, which means organized tropical activity won’t be a concern for us even in the event something forms elsewhere.

The only safe harbor for would-be tropical systems in the weeks ahead will be down in the western Caribbean, where jet stream winds could see occasional breaks. Even so, our extended range models show negligible odds of development for this cordoned off part of the tropics through next week.

Probability of tropical storm winds (winds greater than 38 mph) through November 17, 2023, from the European model medium range forecasts. Shaded magenta areas indicate a very low (less than 10% chance) of occurrence. Credit: ECMWF

When do the last tropical systems typically form?

Over the past 50 years, the median date for the last named Atlantic storm (subtropical storms included) is November 7^th. As you might imagine, there’s a wide range of dates for the formation date of the last named storm – from as early as September 20^th (Tropical Storm Harvey in 1993) to as late as December 30^th (Tropical Storm Zeta in 2005). Most years fall between these two extremes but closer to the beginning of November.

Whittling it down to the formation date of the last Atlantic hurricane, over the past 50 years, the range spans from September 4^th (Hurricane Erika in 1997) to December 20^th (Hurricane Lili in 1984), with October 24^th the median date of the last Atlantic hurricane formation.

How many hurricanes have hit the U.S. after November 6^th?

Not many. Of the nearly 380 U.S. hurricane landfalls on record (including Puerto Rico and the U.S. Virgin Islands), only three have struck the U.S. after November 6^th – Kate on November 21, 1985, Lenny on November 17, 1999, and Nicole on November 10^th last season (2023). This means by today’s date, 99% of U.S. hurricane landfalls have historically occurred.

Wrapping up hurricane season for now

With 96% of typical hurricane season activity in the rearview mirror and 99% of historic U.S. hurricane landfalls behind us, the risk of significant storm threats in the remaining weeks is low. Since forecast models are advertising an increasingly hostile Atlantic in the weeks ahead and no new development in sight, the routine issuance of our daily tropical newsletter will end for now. Of course, if anything changes, you’ll be the first to know from me and our Local 10 Weather Authority team. In the meantime, enjoy the spoils of dry season. You earned it.