30 September 2021

Wrapping up September with 20 named storms

Hurricane Sam continues is trek over the open ocean north of the Lesser Antilles, still as a formidable Category 4 hurricane.  It has persisted as a Category 3-4 hurricane Saturday morning, and will probably remain at that intensity for another couple of days until it starts to find cooler water and strong vertical wind shear. 

Sam is forecast to pass just east of Bermuda, and the island is under a tropical storm watch.  Then it will gradually transition to an extratropical cyclone by the middle of next week and will be a potent player in the north central Atlantic, including the UK perhaps, eventually.

On Wednesday afternoon, the tropical wave near the coast of Africa, Invest 90L, was upgraded to Tropical Depression 20, then to Tropical Storm Victor six hours later.  The only other year to have 20 named storms form before October was 2020.

Victor is an impressively large circulation -- much larger than Sam was when it exited the continent.  And it also became a tropical storm REALLY far south at 8.3N... the only other storm to form farther south than Victor was Kirk in 2018 (8.1N).  Bret in 2017 is a close contender, as it became a wave with tropical storm force winds at 7.8N but wasn't officially a tropical storm until 9.2N.

If this had formed a couple weeks sooner, its odds of being a long-track deep-tropics hurricane would be really good, but that gets harder to do this late in the season.  The NHC forecast is in good agreement with the the models, which takes Victor toward the northwest and over cooler waters within a week.

Victor has a shot at becoming a hurricane on Friday, but after that the window of opportunity begins to close on it.  If it does, it would be the season's 8th hurricane, and recent seasons with an 8th hurricane on or before October 1 are 2020, 2017, 2012, 2005, 1995...

As of now, there are not any other areas of interest, but October can be a busy month, and we tend to see development much closer to land: the western Caribbean, Gulf of Mexico, and off the southeast US coast. Only one more name is left on the regular list: Wanda... then we move to the new auxiliary list that I mentioned in Tuesday's post.

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