The Weather Notebook: Secrets of Hurricane Forecasting

Secrets of Hurricane Forecasting
Listen in RealAudio
Email Your Comments

Dave Thurlow, Host

Hurricane Forecast Team
Hi, I'm Dave Thurlow and this is The Weather Notebook. How do they do it? Every spring Dr. William Gray and several colleagues issue an outlook for the number of Atlantic hurricanes in the season to come. This year Gray and company are calling for a busy season-they're expecting 14 tropical storms and 9 hurricanes. That's about 50 percent above average. It's also the most activity Gray has ever predicted before a season began.

How does this group predict a whole season of tropical weather months in advance, when we can't even get tomorrow's rain shower pinned down? It's all done through statistics.

The regular weather forecast you hear each day is based on specific weather features that are tracked by a computer model. But Gray isn't predicting individual hurricanes. Instead, his team gives a total number based on their look at long-term climate patterns that tend to cause greater or lesser activity.

In looking at 50 years of hurricanes, they've isolated 13 different factors. One of the biggest is El Nino. When there's an El Nino in the Pacific, it usually creates a hostile environment for Atlantic storms and helps produce a quiet hurricane season like we had in 1997. This year, it's just the opposite. We have a La Nina in progress in the Pacific and it creates light upper level winds in the Atlantic, which hurricanes love.

Like any forecaster, Bill Gray doesn't win them all. Last year he called for an average season, and we got an active one. But when Gray does see a busy year coming, it usually arrives on cue--so you might want to pick up those batteries and bottled water while you can.

Bob Henson is today's contributing writer. Thanks to Subaru, the beauty of all wheel drive with major support provided by the National Science Foundation.