In 2011, the "L" storm (Lee), formed on September 2nd. Lee was the 13th storm last year, as an unnamed tropical storm formed on September 1st, which was classified as such during the postseason analysis.
In 2005, Tropical Storm Maria was the 13th named storm of the season and it too developed on September 2nd. So we were short by two days.
|Yesterday's Tropical Overview. Credit: NOAA|
That said, let's look closer at this season. The index we refer to as Accumulated Cyclone Energy, or ACE, is a nice guide to determine just how active a season really is. ACE is a nice little tool to tell us generally how active a season has been. Unfortunately, it draws mainly on duration of wind speed (how long does the storm hold maximum sustained winds of XX mph?). As we learned from Isaac, wind speed isn't always the best gauge of how powerful a storm is. Still, this at least gives us some way of ranking prior seasons vs. the current one or each other.
Think of it sort like meteorological sabermetrics.
So far (through yesterday), according to Dr. Ryan Maue's website on ACE, we sit at 51.6525 for the season. How does this compare to 2011? Through the end of Hurricane Maria in 2011 (not counting the unnamed storm #13), the total ACE in the Atlantic was 73.233. Katia and Irene contributed to over half of that total. In 2005, we were at over 116 through Hurricane Maria that year! The even more intense start to the 1933 season had an ACE of over 147 by storm #13 of that year.
So while 2012 is generally keeping pace with 2005 and 2011, in terms of intensity, it's absolutely woeful. Although many criticize the National Hurricane Center for naming paltry, wimpy storms 3,000 miles from land, it's important for the historical record. This is why we have indices like ACE, to help us get under the hood and see what's really going on.