2013: 6th lowest Accumulated Cyclone Energy since 1950

The 2013 Atlantic Hurricane Season is one of the quietest on record. There have been 13 named storms, but only one hurricane, and no major hurricanes. The number of tropical storms is very misleading, since 8 out of the 12 tropical storms had maximum winds of 50 mph or less. One way to measure how active the tropics are is by looking at the Accumulated Cyclone Energy (ACE) which takes into account the strength and duration of the storm. Even though there have been 13 named storms, the ACE for this season is very low. The current ACE of 28.55 is only 29% of normal and the sixth lowest since 1950.

We are well past the peak of the hurricane season, and unless there is a late-season storm, the 2013 ACE will be the fifth lowest on record. At this point, the last time the seasonal ACE was this low in early November was in 1994. If there are no more storms, the last time the total seasonal ACE was 28.55 or lower was 1982.

  Basin   Current YTD   Normal YTD % of Normal YTD Yearly Climo*
  Northern Hemisphere   360.595   504 71% 562
  Western N Pacific   233.8   261 89% 302
  Central N Pacific   6.31      
  Eastern N Pacific   75.355   135 55% 138
  North Atlantic   28.55   97 29% 104
  North Indian   22.89   10 228% 18
  Southern Hemisphere +   0.6125   3 20% 209
  Global++   484.8900   680 71% 771

*Climatology from historical 1981-2010 Tropical cyclone best track datasets
+Reset for 2013-14 season: Southern Hemisphere year to date is the seasonal value from October – Current due to offset nature of SH TC season
++Global Year to Date ACE values include calendar year totals for both hemispheres. Southern hemisphere contribution to global YTD for 2013 includes 124 ACE units from January – September 2013

Data from

Normal ACE value has long since peaked
Normal ACE value has long since peaked

Fred Campagna

President and Chief Meteorologist - Right Weather LLC AMS Certified Consulting Meteorologist #756 AMS Certified Broadcast Meteorologist #126

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