Hurricane season outlooks of limited use

RALEIGH, N.C. – After high-profile, back-to-back busts by hurricane predicting organizations, critics have questioned whether long-range outlooks do more harm than good, the Associated Press reported in a recent story.

Forecasts for the six-month hurricane season can pretty accurately predict an above- or below-average season, even predict the likelihood a major storm will hit somewhere along the United States coast.

The AP contacted the emergency management agency in every coastal state from Texas to Maine and asked whether these seasonal forecasts play any role in their preparations for June 1. Their response was unanimous: They’re a great way to get people thinking about the upcoming season, but that’s about it.

From the beginning, hurricane-forecasting pioneer William Gray issued disclaimers with his forecasts, like the one from May 1989 that asserted the forecast “can only predict about 50 percent of the total variability in Atlantic seasonal hurricane activity.”

North Carolina State University’s Lian Xie says in a boldface disclaimer in his 2008 forecast: “Results presented herein are for scientific information exchange only … Users are at their own risk for using the forecasts in any decision making.”

This season, Xie and master’s student Elinor Keith are forecasting 13 to 15 named storms, but again with caveats — the highest probability they offer for any particular number in that range is 11 percent. They predict six to eight of those storms will become hurricanes — but put the probability of seven occurring at just over 14 percent.

Others have decided that there is need to qualify their forecasts, as well. Colorado State University predictor Phil Klotzbach says his next update will include an extra section “that deals with forecast uncertainty.”

And when the National Oceanic and Atmospheric Administration released its 2008 outlook at the end of May, it included for the first time a pie chart showing the likelihood that its prediction of 12 to 16 named storms was accurate. The verdict: About 65 percent for the whole range.

So why keep doing them? Gray and Klotzbach opened this year’s forecast paper with that very question.

The answer they give: Because they add to the overall understanding of how hurricanes work.

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