June 16, 2000 | By: Aimee D. Heald

Although Kentucky hasn't yet been hit with the extreme drought conditions of 1999, the state still needs rain, and lots of it.

University of Kentucky College of Agriculture Meteorologist, Tom Priddy, believes warm sea-surface temperatures in the Gulf of Mexico combined with weak-to-moderate La Nina conditions in equatorial Pacific could add up to enhanced tropical storms in the Gulf of Mexico and possibly some rainfall for Kentucky and the Ohio Valley this hurricane season.

"Activity is already starting to pop in the Gulf," Priddy said. "As early as last week, satellite maps were showing moderate convective showers and thunderstorms in southern sections of the Gulf of Mexico."

Some of the weather patterns the Commonwealth is experiencing this week could be due to what the National Weather Service named Tropical Depression One in the Gulf of Mexico last week.

According to the Climate Prediction Center, 2000 could be an above-average Atlantic hurricane season, by favoring reduced vertical wind shear across the western tropical Atlantic and Caribbean Sea, and easterly winds from Africa that are conducive to the development of tropical storms and hurricanes.

Historically, when similar atmospheric conditions were present in an active hurricane era, 75 percent of the Atlantic hurricane seasons featured above-average activity.

The continuation of the current atmospheric irregularities depends partly on the ongoing La Niña in the tropical Pacific. A consensus of the latest numerical and statistical model forecasts indicate a continuation of La Niña conditions at least through July. Thereafter, the forecasts tend to diverge, but a majority indicate either near-normal or weak La Niña conditions continuing to the end of the year.

"We expect that even if La Niña fades by late summer, the existing tropical rainfall anomalies will not be totally destroyed," Priddy said. "So, that probably will not unduly impact the favorable large-scale atmospheric circulation pattern that currently exists."

Another contribution to conditions favorable for an active hurricane season comes from the above-average sea surface temperatures that have persisted since 1995 across large portions of the North Atlantic.

Below are some typical features of above-average active-hurricane years.

Most of the above-average activity will occur from August to October, during the peak months of the season; the season often features at least 11 tropical storms, seven or more of which typically become hurricanes, and three or more of which become major hurricanes; Overall activity, including measures of storm duration, intensity, storm numbers and hurricane numbers, is very high.

Many of the storms are expected to develop over the tropical Atlantic, and then move westward toward the Caribbean Islands or the United States, thereby putting coastal areas at an increased risk of experiencing a tropical storm or hurricane.

In active years, the Caribbean Islands and the U.S. each experience an average of two to three hurricane strikes. For the Caribbean Islands, this frequency of hurricane landfall is much larger than observations in inactive years.

"Will Kentucky benefit from this tropical moisture?" Priddy asked. "Just keep your eyes on the Gulf to find out."


Tom Priddy 859-257-3000