September 17, 2002 | By: Aimee D. Heald

Throughout the summer, warmer waters have been churning in the Pacific signaling the return of the weather phenomenon known as El Niño. But what do warm waters thousands of miles away mean for Kentucky weather?

University of Kentucky Agricultural Meteorologists Tom Priddy and Corey Pieper said Kentucky and the Ohio Valley could see a mild and dry fall and winter even though sea surface temperatures are only up 1 degree Celsius along the equator as of Sept. 16. They said studying the last El Niño episode in 1997 and 1998 provides a good guide of what to expect this time around.

"It is important to point out that global impacts of this warm episode should generally be weaker than those we observed in 1997 and 1998," Priddy said. "Although there is uncertainty about the timing and intensity of the peak of this episode, all forecasts indicate a weaker version. However, strong impacts are still possible."

Typically, El Niño has many predictable effects on United States weather patterns. From September through November, fewer hurricanes and tropical storms form in the Gulf of Mexico, Carribean Sea and more occur in the eastern Pacific. Pieper said El Niño does not seem to affect the number of storms in the main Atlantic Basin.

"Also, from December to April, El Niño moves the preferred patterns of storms to produce variations in precipitation and surface temperatures in many regions," he said. "That means the storm track position changes."

During the last El Niño, Kentucky saw January temperatures in the 60s, February temperatures in the 70s and then 80s in March.

"In the 2002 to 2003 El Niño, Kentucky will likely be sandwiched between storms tracking to the north and storms tracking to the south," Priddy said. "This is mostly because the main branch of the polar jet stream will stay well to the north of Kentucky and the Ohio Valley and the southern branch will track well to the south of Kentucky into the Mid-Atlantic states."

Priddy said it's important to remember that even small shifts in the jet steam can have a large impact on a region's weather, which is why no two El Niño episodes are exactly alike.

"The fall and winter months of 1997/1998 were generally dry," he said. "But it was a roller coaster with November having well below normal temperatures and January through March being unseasonably warm at times."

Priddy and Pieper expect precipitation to be below normal and temperatures above normal for fall and winter 2002/2003 in Kentucky and the Ohio Valley states.

"The main point I'm trying to get across is that El Niño will affect Kentucky similar to what we experienced during the last episode," Priddy said. "It's just too soon to tell how great the impact will be."

To keep track of El Niño and other weather matters, visit the UK Ag Weather Center online at


Tom Priddy  859-257-8803, ext. 245