National Hurricane Center to shrink cone of uncertainty, eyes other changes



By Mike Lyons

The first full week of spring produced a typical late March weather pattern across south Florida: mostly sunny, mild and breezy. But it won’t be long before the heat and humidity of summer returns, marking the beginning of the rainy season (usually around May 20) and the start of the hurricane season (June 1).

There is already a lot of talk about the upcoming hurricane season. Joe Bastardi, Expert Senior Forecaster at AccuWeather, thinks the tropics will be active again. Bastardi’s early forecast calls for 13 storms, eight hurricanes and two major hurricanes.

Dr. William Gray and his group at Colorado State University will issue their updated predictions on April 7. Gray’s preliminary forecast for 2009, issued last December, called for a busy season with 14 storms, seven hurricanes and three major storms.

Meanwhile, forecasters at the National Hurricane Center may be making changes in some of the products they use to keep track of all those tropical systems. Last month, hurricane forecasters and scientists gathered in St. Petersburg for the 63rd Interdepartmental Hurricane Conference for an update on all things related to hurricanes.

Among the highlights: changes in the Saffir-Simpson scale, a new storm surge scale, expanding the hurricane warning lead time and reducing the size of the cone of uncertainty.

Officials are considering removing any mention of storm surge from the Saffir-Simpson hurricane scale.

The scale, designed by engineer Herb Saffir and former National Hurricane Center Director Robert Simpson, determines the intensity of a hurricane based on wind speed but does little to assess the impact of storm surge.

Just ask folks in Texas who experienced Hurricane Ike. On the Saffir-Simpson scale, Ike was a Category 2 storm but produced a storm surge comparable to a Category 3.

Officials are thinking of eliminating storm surge values from the current Saffir-Simpson scale and creating a new storm surge warning scale.

Still, it may take several years to develop the storm surge scale.

There are a number of major technical issues to be resolved (What level of water would qualify? Would there be storm surge watches and warnings?).

Bill Read, the director of the National Hurricane Center, estimates it may be three to five years before the new scale is implemented.

By early next year, however, the lead-time for hurricane warnings and watches could be expanded.

Currently, the NHC issues a hurricane watch 36 hours before the storm is expected to make landfall, and a hurricane warning 24 hours in advance.

By next year, those lead times could be expanded to 48 hours for a watch and 36 hours for a warning.

The reason? Hurricane forecasting continues to become more and more accurate. Last year was another record-setting year in track forecasts, leading NHC officials to propose the expanded lead times in watches and warning.

In fact, 2008 was the best year in history for both short range (12, 24, 48 hour) and long range (3-5 days) forecasts from the National Hurricane Center.

As a result, officials will be reducing the famous cone of uncertainty for the 2009 season.

Even though it’s nice now, it won’t be long before that hurricane angst returns for all of us, as we wonder, “What type of year will we have in the tropics?”


Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.