TUESDAY AUGUST 22 - HURRICANE FORECASTING: HOW GOOD IS IT?


Dr. William Gray is a well-known hurricane researcher who issues long-range hurricane outlooks each year. Here's a look at his forecasts for the last few years, compared to what actually happened:


Year   Forecast    Actual

1995 8 11
1996 6 9
1997 7 3
1998 6 9
1999 9 8

If we look just at the difference between the forecasts and reality, the average error is 3. Now, considering that the average number of hurricanes per year in the Atlantic is only around 6, that seems like a pretty large error. In fairness to Dr. Gray, if we include all his forecasts back to when he first started in 1984, the average error does go down to around 2.

But more important than the specific numbers is whether the forecasts were able to pinpoint active and non-active hurricane years - that is, whether the number of storms would be above or below average. By this measure, the forecasts are on target about 2/3 of the time, which says to me they do provide useful information.

With that in mind, my advice is not to focus so much on the specific numbers. Instead, simply look at whether the hurricane season is expected to be active or not. And remember, even a year with only a few storms can be devastating - there were only 4 hurricanes in 1992, but one of them was named Andrew.

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