Early storm warning for the Atlantic coast
ARMENIA's earthquake currently has the natural-disaster spotlight. But don't forget this year's Atlantic hurricane season. It was one of the most active in several decades. And Gilbert - the most intense hurricane on record - caused major devastation. This may be telling all regions exposed to Atlantic hurricanes to pay even more attention to storm disaster preparedness than ever before.
Reviewing the storm season that ended Nov. 30, William M. Gray, a meteorologist at Colorado State University, says we may be returning to a period of more intense hurricane seasons such as prevailed a few decades ago. He notes that this year's activity was more like the hurricane seasons of 1947 to 1969 than the relatively inactive seasons of 1970 to '87.
This, of course, is speculation. A single season doesn't constitute a trend. When it comes to predicting the activity of a particular year, however, Gray - with several successes already to his credit - hit 1988 virtually on the nose.
Last May, he forecast 11 hurricanes and tropical storms strong enough to be given a name. He got 11. He forecast 30 hurricane days and 50 named storm days. He got 26 and 53 days, respectively. A hurricane day or storm day is any part of a day when such a storm is raging.
He also predicted a statistic he calls hurricane destruction potential (HDP). This, roughly, is the sum of the squares of the maximum wind speeds, calculated storm by storm, for the entire season. Gray predicted an HDP of 75 and got 79.
This is an amazingly accurate forecast to be made even before the hurricane season officially began June 1. That Gray expected 7 of the 11 storms to be hurricanes while only 5 reached that strength does not tarnish his achievement. He forecast a season significantly more intense than normal, and that's what happened. This record supports his claim to have identified several environmental factors - such as certain high-level wind patterns and tropical Pacific sea surface temperatures - that appear to govern the level of Atlantic hurricane activity.
Gilbert wasn't the only ominous phenomenon of the season. Gray points out that the storms generally developed from disturbances coming off Africa and traveling eastward through low latitudes. Such disturbances tend to evolve into the more intense hurricanes. Also, the long-playing West African drought broke with the most intensive rainfall since 1969.
These developments are all of a piece. They are typical of weather patterns of the 1947-69 hurricane seasons. If we are returning to those seasonal patterns, it would be good news for West Africa. But it would mean that the hurricane-exposed Atlantic regions, now far more heavily populated than they were 20 years ago, would face increased risk of hurricane disaster. This adds to the already substantial need for these regions to control development, build for storm safety, and increase preparedness.
A Tuesday column