Unlikely Small Storm In Central Atlantic Rapidly Deepens To Category Three Strength Last Week

It has been somewhat of a strange season in the Atlantic.  The 2012 season has had its share of surprises.  Whether it has been exceeding pre-season expectations, or even going toe to toe with some of the most active years in terms of the number of named storms, this season, which wasn’t expected to be that active thanks to a forecasted El Nino, 2012 has opened some eyes.

Another surprise so far this season had been the lack of major hurricanes.  Up and until last week, no major hurricanes had developed in the Atlantic this season.  So, despite the record number of storms, none grew to become Category Three strength or better.  Hurricane Michael changed all of that.  A small tropical cyclone that first emerged in the Central Atlantic, Michael wasn’t expected to become much of a storm.  It was forecast to peak in four days with 45 mile per hour winds after first becoming a storm on the day after Labor Day.

However, the storm didn’t cooperate.  Instead, it went through a rapid deepening phase that saw its minimum central pressure drop 47 millibars within 60 hours.  By early Thursday morning, September 6th, the storm became the first major storm of 2012 in the Atlantic with 115 mile per hour sustained winds, gusts up to 120 knots, or 140 miles per hour, and a minimum central pressure of 965 millibars, or 28.50 inches of Hg.  Prior to that, the strongest storm to date this season had been Hurricane Gordon, another Central Atlantic storm that experienced a bit of a deepening phase as well.

Michael has been a very small storm throughout.  As of the latest advisory from the National Hurricane Center, the storm has hurricane force winds extending some 25 miles from the eye, and tropical storm force winds reaching out some 80 miles.  At peak intensity, the storm had hurricane force winds extending out only 15 miles and tropical storm force winds reaching out some 70 miles.  During its initial genesis, the storm only had tropical storm force winds reaching out some 35 miles.

This small size and rapid deepening with Michael was in sharp contrast to both recent hurricanes Isaac and Leslie, which were both very large storms with tropical storm force winds extending at least 200 miles from the center, but they struggled to intensify throughout their lifetimes.  With the development of Michael, there have been 13 depressions, 13 named storms, 7 hurricanes, and one major hurricane.