Friday, November 30, 2012

The Thankful End of Hurricane Season Today

The 2012 hurricane season officially closes out today, with an active season finally getting shoved into the annals of history.  Only 1933 (21) and 2005 (28) outdid 2012 (19) in terms of sheer numbers of tropical cyclones and 2012's season equaled the quantity of 2010 and 2011 in terms of storms that developed.  From a number's standpoint, it was rather active...even compared to the current active cycle that started in 1995.  

An average season since '95 features 15 named storms and eight hurricanes, which 2012 outdid on both metrics.

In terms of "bang for buck", this season had a relatively modest sum of accumulated cyclone energy, which is a metric that adds the values up of wind speed for duration of the storm.  The season total of 123 comes in below the "active cycle" average of 138.  ACE totals can be ratcheted upwards quickly with powerful Category 4's and 5's or long-lasting and long-track storms that spin for numerous days -- this season had no storm stronger than a Category 3 and only Nadine was a real long duration storm (one of the longest on record).   There were a number of weaker tropical storms and short duration systems that developed this year, which aided in keeping the ACE statistic a bit closer to normal despite an active year overall.

ACE is a good but imperfect metric because it solely looks at wind speed and duration and not size of storm when it comes to ranking cyclone energy. Sandy's ACE score was just 12.5, less than half of Nadine's...but it also lasted for one-third the time of Nadine.


The 2012 hurricane season had five relatively noteworthy storms -- all different, all with rather large impacts.   First, Debby in the Gulf of Mexico in late June as it brought over twenty inches of rain to the Sunshine State. Ernesto followed as a hurricane in the Yucatan.  Isaac was the Gulf Coast's hurricane, striking Louisiana at the end of August.  Nadine, which flirted with longevity records in the Atlantic in late September into early October as it spun around the Central Atlantic in a couple of loops.   Last, Sandy...and we know what that storm did at the end of October.  There were others through the year that impacted other parts of the Atlantic but by and large, those five were the most noteworthy of the season.

The season's activity was above what most forecasters projected this year as El Nino failed to materialize in the Pacific.  This resulted in not only an active start but an active September and October that went out with a major bang with Sandy at the end of October.

The entire 2012 hurricane season was condensed into a 4 1/2 minute video that NOAA put together yesterday for release on YouTube.  Alberto to Tony, with Sandy in between, spinning through the Atlantic from May through October.