Space Weather

Wednesday, September 27, 2023

As we head toward October, how is the season stacking up?

 

When I posted my hurricane Outlook in the Spring, I said this would end up an active season in spite of the idea of a moderate to strong El Nino; I outlined how those record warm Sea Surface Temperatures in the Atlantic Basin, would help counter the El Nino. My call then was for 14-20 named storms, 8-12 hurricanes, 3-5 major hurricanes. The CONUS could see 2-4 landfalls with one of them possibility being major. The ACE would be 100-150.


So far, the Atlantic hurricane season has been proceeding at a blistering pace. So far this year, there have been 17 named storms, including an unnamed subtropical storm off the East Coast in mid-January, and 6 hurricanes, of which, 3 were major  category 3 or above, Category 5 Hurricane Lee and Category 4 hurricanes Franklin and Idalia. Tropical Storm Harold made landfall in south Texas. After briefly attaining Category 4 strength on August 30, Hurricane Idalia made landfall in the Florida Big Bend as a high-end Category 3 hurricane, before making another landfall in South Georgia as a tropical storm. Hurricane Lee rapidly intensified into a Category 5 hurricane, then after narrowly missing New England, he made multiple landfalls in Atlantic Canada. Tropical Storm Ophelia made landfall in North Carolina.


Credit WPLG 10, Miami, Florida

 At the time of this posting, The North Atlantic ACE Index stands at roughly 123.5 points, which is 153% higher than the average for this time of the season.


Credit Dr. Ryan N. Maue

There are only 5 names left on the official list for the Atlantic Basin. 



We still have two months to go in this year’s hurricane season, based on the ACE index, we still have 22% of the season's activity ahead of us for October and November. An average hurricane season generates another four storms, two of which become hurricanes, from October through the season's end. So, there is plenty of time to add to the already impressive numbers.

The SSTs in the Atlantic basin are still at record warmth, particularly in the part of the Caribbean Sea and Gulf of Mexico most prone to late-season storms.

As we head into October, the Cape Verde season with the African easterly waves in the eastern Atlantic Ocean, and in the center of the Atlantic fades. This time of year, we typically look for the formation of tropical cyclones to happen in the northwestern Caribbean, or in the Eastern Gulf of Mexico off the coast of Florida, as well as the Western Atlantic along the East Coast. The reason for this is that, SST in the Atlantic Ocean typically start to cool and wind shear increases, so the majority of the tropical activity shifts back into the Caribbean and Gulf of Mexico, where water temperatures are usually still very warm, and old frontal boundaries tend to hang around, which often can be the focal point for tropical development.

On average, October ranks third behind September and August for months with the most named tropical systems in the Atlantic basin. In recent years, some of the strongest and most impactful hurricanes have struck in October. Some of which were, Hurricane Hazel which made landfall as a strong Category 4 between North and South Carolina on October 15, 1954, Category 5 Hurricane Michael in 2018 which caused catastrophic damage in both Mexico Beach and Panama City, Florida, with estimated sustained winds of 160 mph., Hurricane Delta in 2020 and Superstorm Sandy in 2012.

Dating back to the 1800s, there have been 172 tropical storms and 252 hurricanes in October. Eight of those storms have reached the strongest strength: Category 5 with sustained winds over 157 mph.

Hurricane season usually quiets down even more as we head into November, especially for the U.S, ​with just 56 total in 171 years of record keeping. November U.S. hurricane landfalls are extremely rare, with just four ever documented.

So, if you live along the Gulf Coast or along the East Coast, don't let your guard down when the calendar turns to October.

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