17 September 2019

Humberto, Imelda, and soon-to-be-Jerry scattered across the Atlantic

The Atlantic basin now has two named storms, and likely three by day's end.  We have Humberto heading for Bermuda, Imelda inland over Texas, and Tropical Depression 10 east of the Lesser Antilles. 

Humberto is now a Category 2 hurricane and is continuing its trek toward Bermuda. It's centered just 450 miles west of the island and moving toward the east-northeast at 12mph.  They are under a hurricane warning, and dangerous tropical storm force winds should arrive by Wednesday afternoon.  While Humberto is the season's third hurricane, it's only the second Category 2+ hurricane (Dorian was the other).  The latest NHC forecast does bring it up to Category 3 intensity on Wednesday as it passes by Bermuda.  I have a long, updating radar loop from Bermuda at http://bmcnoldy.rsmas.miami.edu/tropics/radar/ which could become interesting on Wednesday.
Tropical Storm Imelda just formed on Tuesday afternoon... inland near Houston TX.  It's certainly unusual to have a tropical storm form over land, especially without so much as a tropical storm watch leading up to it (this was never a "Potential Tropical Cyclone", despite that term being implemented solely for this purpose in 2017).  The first advisory on it was as Tropical Depression 11, on Tuesday early afternoon right on the coastline. It has peak sustained winds of 40mph and it's moving toward the north at 7mph.  It is forecast to weaken, but stranger things have happened (like a few hours ago).

Even prior to this rapid genesis, the big concern was flooding, and that remains the case. Rainfall totals in the area could easily exceed a foot as the storm drifts northward over the next couple days.

Imelda is a new name this year, introduced after Ingrid was retired in 2013.  Curiously, "I" storms are the most-frequently retired, so we'll see what Imelda does in the coming days -- hopefully not enough to earn retirement.

Finally, Tropical Depression 10 is about 1100 miles east of the Lesser Antilles and is forecast to become the season's tenth named storm very soon: Jerry.  Model guidance is in good agreement on it reaching somewhere around the northern Leeward Islands on Friday and the NHC forecast is for it to reach hurricane status around that time.  Beyond that, a slight northward bend will bring it toward the eastern Bahamas later this weekend.  The map below shows the arrival time and probability of tropical storm winds based on the latest 5-day track and intensity forecast.

Beyond that, there is still way too much spread just in the European model's ensemble forecasts to say much.  The realistic scenarios range from a hurricane as far south as Puerto Rico to an early recurve out to sea by about 65°W.  Not only is this a small and weak system, the large-scale steering features will be manipulated and altered by Humberto.  For now, just stay tuned and I will be watching for changes or trends in the ensemble guidance.

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