[Coral-List] NOAA issues 2006 Hurricane Outlook and CRW's thoughts on 2006 Caribbean bleaching season

Mark Eakin Mark.Eakin at noaa.gov
Mon May 22 14:59:21 EDT 2006

The 2006 Outlook was just released.  The report states:
"The outlook calls for a very active 2006 season, with 13-16 named  
storms, 8-10 hurricanes, and 4-6 major hurricanes. The likely range  
of the ACE index is 135%-205% of the median. This prediction  
indicates a continuation of above-normal activity that began in 1995.  
However, we do not currently expect a repeat of last year’s record  

Details can be found at: http://www.cpc.ncep.noaa.gov/products/ 

The good news is the last sentence "However, we do not currently  
expect a repeat of last year’s record season."
Unfortunately, the 2005 Outlook, issued 16 May 2005 read:
"The outlook calls for 12-15 tropical storms, with 7-9 becoming  
hurricanes, and 3-5 of these becoming major hurricanes. The likely  
range of ACE index is 120%-190% of the median. This prediction  
reflects a very likely continuation of above-normal activity that  
began in 1995."
As you see, the outlook for 2005 was slightly milder than the outlook  
for 2006.

We are, of course, quite concerned about the potential risk to lives  
and property for those of you in the wider Caribbean region.   
Additionally, we are concerned about this forecast because there is a  
strong correlation between hurricane activity and the amount of the  
Caribbean region that experiences bleaching level stress.

Two of the statistics used in the hurricane outlook, the number of  
named storms and the Accumulated Cyclone Energy (ACE) index correlate  
highly with annual accumulations of our Degree Heating Week (DHW) for  
the waters of the wider Caribbean (10-30 degrees North, 60 degrees  
west to the Americas) since 1985.  The r^2 values for the correlation  
between the percentage of the Caribbean at DHW >= 4 vs. (1) named  
storms or (2) ACE reveal that these variables explain 80% and 74% of  
the variance, respectively.  The 2006 outlook's ACE value of 135-205%  
corresponds roughly with the values seen in 1996, 1998, 1999, and  
2005, or about 5-15% of the Caribbean  reaching DHW of 4 or greater.   
As a comparison, over 40% of the Caribbean reached DHW of 4 or  
greater in 2005.

A factor used in calculating the ACE is the current ocean  
temperature.  Much of the North Atlantic is currently warmer than  
normal and has been for most of 2006.  This, of course, is the major  
factor that contributes to mass bleaching.

I caution all of you reading this that we are far from having a  
bleaching forecast system.  These are not official outlooks, but  
simply a heads up based on past correlations.  We are starting work  
to develop a bleaching forecast system that will hopefully allow us  
to release bleaching outlooks similar to the hurricane outlooks.  In  
the meantime, you should all consider that bleaching in many parts of  
the Caribbean is a very real possibility for 2006.


C. Mark Eakin, Ph.D.
Coordinator, NOAA Coral Reef Watch
National Oceanic and Atmospheric Administration
Center for Satellite Applications and Research
Satellite Oceanography & Climate Division
e-mail: mark.eakin at noaa.gov
url: coralreefwatch.noaa.gov

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1335 East West Hwy
Silver Spring, MD 20910-3226
301-713-2857 x109                   Fax: 301-713-3136

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