November 5, 1999 | By: Aimee D. Heald
LEXINGTON, KY

You've heard about Y2K, but have you heard about SYW? SYW refers to Second-Year Winter, resulting from a second La Nina season. Last year, La Nina brought Kentucky a mild winter, but the SYW could be much different.

La Nina, the opposite of El Nino, is the cold sea-surface temperatures in the equatorial Pacific. Okay, you know what it is, but what does it mean?

"While we tend to expect extreme weather with El Nino, La Nina can provide Kentucky with some wild weather too," Tom Priddy, agricultural meteorologist for the University of Kentucky's College of Agriculture, said. "La Nina means extreme variability."

The Commonwealth could experience mild weather followed by bouts of extreme blasts of cold air. These blasts could include frigid arctic air, sub-zero temperatures and widespread snow and ice.

These periods could last from two to four weeks over much of the United States. The cold blasts typically are followed by very mild conditions, thawing temperatures, and the risk of heavy rains and flooding.

"Some climatologists believe last winter deviated from a typical La Nina winter," Priddy said. "This was due to tremendous heat still dissapating from the huge El Nino that ended during May of 1998."

Looking back at Kentucky rainfall, when La Nina lasted into a second year, with a drought the previous summer, the results are surprising. First, for most moderate La Ninas, summertime drought was the common weather in Ky. This doesn't mean droughts in the state are caused by La Nina, but often when La Nina occurs, Ky. does have dry summers.

Second, when La Nina is coupled with dry weather in Kentucky, it has tended to end in a bang. For example, after the drought of 1988 and then a La Nina winter, Kentucky received more than 10 inches of rain in March 1989.

So, what about this winter? The long-range outlook calls for near-normal temperatures and above-normal precipitation, with La Nina fading in March 2000. Still, those years where La Nina caused drought in Ky. indicate the following winter had a roller-coaster of temperatures and wet winter months, especially second-year winters.

For the latest weather news for Kentucky and the US, log onto http://wwwagwx.ca.uky.edu/ – 30_--

Contact: 

Writer: Aimee D. Heald 606-257-9764

Source: Tom Priddy 606-257-5850