Annual Global Climate and Catastrophe Report: Impact ... - Aon

AnnuAl GlobAl Cli mAte And C AtAstroph e r e port
Historical Atlantic Hurricane Season Predictions
Abundant media attention has been given to various organizations across the world that issue hurricane season
predictions for the Atlantic and Caribbean Oceans. These organizations utilize meteorological and climatic data
obtained, in some instances, up to six months in advance to determine how active or inactive the following
year’s Atlantic Hurricane Season will be. Several different professional entities issue these forecasts, ranging
from governmental agencies to universities to private companies. The three organizations that consistently
make their forecasts public are:
• Colorado State University (CSU), a forecast group sponsored by Colorado State University and private
companies led by Dr. Philip Klotzbach and Dr. William Gray;
• the National Oceanic and Atmospheric Administration (NOAA), the United States’ official governmental
climatological and meteorological office; and
• Tropical Storm Risk (TSR), an Aon Benfield-sponsored forecast group based in London, England led by
Professor Mark Saunders and Dr. Adam Lea.
Some of these entities disclose in detail the parameters being used to derive these forecasts, while others cite
general factors for the reasoning of their predictions. For the five-year period shown here, Colorado State
University (CSU) and Tropical Storm Risk (TSR) provide specific numbers, while the National Oceanic and
Atmospheric Administration (NOAA) provides a range of values. Starting in December 2009, CSU started
issuing their forecasts utilizing a range of values.
The forecasts for the last five years made between the period of May 1st and June 10th along with the actual
total number of named storms, hurricanes and major hurricanes are shown in the following figures. The May/
June forecast was chosen due to the availability of forecasts from each organization. Additionally, a five-year
cumulative forecast is shown to emphasize that short-term (one-year) forecasting is often more error-prone
than long-term forecasting.
Figure 18: 2009 Forecast
forecast
parameter
18
may/June Atlantic hurricane season forecast
25-Year Average Csu noAA tsr season total
Named Storms 11.0 11 9-14 11 9
Hurricanes 6.4 5 4-7 5 3
Major Hurricanes 2.6 2 1-3 2 2
Figure 19: 2008 Forecast
forecast
parameter
may/June Atlantic hurricane season forecast
25-Year Average Csu noAA tsr season total
Named Storms 11.0 15 12-16 14 16
Hurricanes 6.4 8 6-9 8 8
Major Hurricanes 1.2 4 2-5 3 5