09 September 2021

Larry weakens, Mindy forms during peak of season

Since my previous post on Monday, Hurricane Larry has weakened only slightly but is still a large and powerful hurricane located just east of Bermuda.  Then, the disturbance I first wrote about on September 1st down near Colombia (later tagged Invest 91L) was upgraded to Tropical Storm Mindy just before landfall on the Florida panhandle on Wednesday afternoon.

Once Larry clears Bermuda today, it's not done with land impacts.  A hurricane watch is in effect for eastern Newfoundland, and Larry will reach the island on Friday night... very likely as a hurricane. It's reminiscent of Igor in 2010, and that storm's encounter with Newfoundland earned Igor's retirement as a name.

From the track map at the top of the post, we can see the 10-day journey that Mindy took from the coast of Colombia to the Florida panhandle... it's been a long time coming but it finally got organized on Wednesday afternoon and quickly wrapped up to become a tropical storm.  This radar loop (latest available at http://bmcnoldy.rsmas.miami.edu/tropics/radar/) shows the quick development and landfall.

Mindy has since weakened to a tropical depression and will re-emerge over the Atlantic later this morning.  Due to increasing vertical wind shear, it is not likely to regain tropical storm status, but could be marginal immediately upon exit, over the Gulf Stream. It's moving quickly so significant rainfall isn't expected, just some heavy rain over eastern Georgia and South Carolina as it passes through.

In terms of named storm count, Mindy is the season's 13th named storm.  The average formation date of the 13th named storm is October 25th, so this is really exceptional.  Only four other years reached this mark by September 8th since 1851: 2020, 2012, 2011, and 2005. Keep in mind that it's only September 9th and we have already used 13 of the 21 names in the regular list! The table below shows the 1991-2020 average formation dates.

In terms of ACE (Accumulated Cyclone Energy), the season is at about 155% of average for the date, using the past fifty years as the baseline.  This season has already accrued more ACE than some entire seasons (2015, 2014, 2013, 2009, 2002, 1997, etc), and Larry is largely to thank for that boost, as that one storm has contributed roughly 40% of the total!

Looking farther east, there's a strong easterly wave just about to exit the African coast, and model guidance favors it for development by the end of the weekend.  Once over the ocean, it should track toward the northwest, no threat to the Caribbean or areas west.  When the time comes, the next name on the list is Nicholas.

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