Though people remember 2005 primarily for it being the year of the devastating Hurricane Katrina, in fact it was a record breaking year for tropical storms in the Atlantic in general. An estimated 3,865 deaths and $130 billion in damages were caused by the 2005 storms. Entering the 2010 hurricane season, forecasters were concerned that that year could at least approach that same level.
First of all, how extreme was 2005? The National Oceanic and Atmospheric Administration (NOAA) lists records of tropical storms back to 1851. It identifies the records since 1900 for the storms that reached the U.S. coastline, and the records since the late 1960s for all storms, as being complete and reliable. For each year, it then tabulates how many named storms there were, how many reached the status of hurricanes, and how many of those were major hurricanes. In addition, it calculates what it calls “Accumulated Cyclone Energy” (ACE), an index that scores the severity of the year from the number of storms, how long they lasted, and their intensity.
Looking at the records, 2005’s 28 named storms was the highest ever. (Second was 1933’s 21. The average from 1968-2009 was 11.3.)
2005’s 15 hurricanes was the highest ever. (Second was 1969’s 12. The average from 1968-2009 was 6.1.)
2005’s 7 major hurricanes was the second highest ever. (1950 had 8; 1961 also had 7. The average from 1968-2009 was 2.3.)
2005’s ACE score of 248 was the highest ever. (Second was 1950’s 243. The average from 1968-2009 was 92.4.)
So pretty close to a clean sweep for 2005.
So what about 2010?
Hurricane forecasting is a highly uncertain enterprise, so even the top experts in the field can only take educated guesses. Perhaps in time it will become a more exact science, but it isn’t yet. But climate scientists look at factors and conditions known to be correlated with varying degrees of hurricane activity, and fit the available data into promising new climate models they have developed, and make the best projections they can.
The estimates are unavoidably loose, but taking into account all the evidence headed into the 2010 hurricane season, the NOAA issued the following projections (the 2005 figures and the 1968-2009 average are included, for comparison purposes):
* A 70% likelihood that there will be 14-23 named storms (2005 = 28; average = 11.3) *
* A 70% likelihood that there will be 8-14 hurricanes (2005 = 15; average = 6.1) *
* A 70% likelihood that there will be 3-7 major hurricanes (2005 = 7; average = 2.3) *
* A 70% likelihood that the ACE score will be 136-238 (2005 = 248; average = 92.4) *
So if things ended up a little below the expected range, it would be an ordinary hurricane year. If things ended up a little above the expected range, it would be a year to rival 2005 and possibly set some records. More likely, if things landed in the NOAA’s expected range, 2010 was projected to be a significantly more severe than usual year for storms, but not reach the historic levels of 2005.
“Hurricane Research Division: Frequently Asked Questions.” Atlantic Oceanographic and Meteorological Laboratory.
“NOAA: 2010 Atlantic Hurricane Season Outlook.” National Oceanic and Atmospheric Administration.