Real-Time Seasonal Hurricane Damage Potential Forecasts
New ECEP science has devised a method to assess the damage potential of the upcoming hurricane season due to winds and coastal surge. In much the same way that current seasonal forecasts forecast hurricane numbers, this new view of the hurricane season uses predicted sea surface temperature patterns and environmental winds from the National Centers for Environmental Prediction (NCEP) ensemble Climate Forecast System (CFS) to infer the key drivers of hurricane damage: namely, hurricane intensity, hurricane size and hurricane translation speed.
The resulting seasonal Cyclone Damage Potential (CDP) index uses a scale from 1 to 10 to assess likely seasonal damage potential relative to other seasons. To put this range into perspective, average historical CDP, over the years 1981 through 2010 is 3.7. The forecast issued August 1, 2016 for an average CDP of 4.2 is a shift down from the forecast issued June 1, 2016 of 5.7 but still slightly above the average historical CDP of 3.7. To put this into context, the highly active 2005 season, for example, had a CDP of 6.3. The actual observed CDP for 2016 was 4.7 - very close to the August 1 mean prediction of 4.2. However, we caution that high CDP does not necessarily correspond with high loss, because CDP forecasts damage potential for the entire North Atlantic and does not necessarily correspond to landfalling damage potential.
Damage potential forecasts were produced using 124 CFS forecasts made throughout May 2016 for the June 1 forecast and throughout July for the August 2 forecast. The figure shows the spread of these forecasts (red line for June 1 and yellow line for August 1) compared to the long-term historical damage potential (black line) and shows the forecast distributions are shifted higher than the historical distribution. Specifically, the August 1 forecast is for 35% likelihood of above normal damage potential, 64% likelihood of normal damage potential and 1% likelihood of below normal damage potential. The long-term average percentages are 33% in each category, so this year the likelihoods are slightly skewed towards the higher categories. This view is generally in line with the seasonal forecasts of tropical cyclone numbers that are slightly higher than average this year. The blue line shows the actual observed CDP for 2016, very close to the mean of the Aug 1 forecasts.
New damage potential forecasts will be released for the 2017 season. Feedback welcome to James Done: done (at) ucar (dot) edu or to ECEP: ecep (at) ucar (dot) edu
For more information, see the UCAR news story or the peer-reviewed scientific paper: ‘Estimating impacts of North Atlantic tropical cyclones using an index of damage potential’.
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