El Nino/La Nina

El Nino: Warming trend in Pacific tropical waters that creates high altitude winds that shear hurricanes in the Atlantic basin. Also tends to create wet, stormy weather in the Southeast United States.

La Nina: Cooling trend in the same waters that creates drier than normal conditions in the Southeast.

Source: NOAA

Well, the first omen of the coming hurricane season is a good one: El Nino looks like he's ready to stick his head up.

But don't put your shutters away just yet.

"While all (computer) models predict warming in the tropical Pacific, there is considerable uncertainty as to whether El Nino will develop during summer or fall," the federal Climate Prediction Center cautions.

El Nino is a warming trend in the Pacific that creates shear winds in this hemisphere - the sort of winds that strip apart hurricanes.

El Ninos are generally good things. A recent federal study of more than a half-century of storms found a correlation between the number of hurricanes and El Nino or cooler water La Nina years. Both devastating Hurricane Hugo in 1989 and the near-miss Lowcountry swipe by Hurricane Floyd in 1999 occurred during strong La Nina years.

But forecasters are beginning to suspect just where and how warm the waters get play bigger roles in Atlantic conditions than the simple emergence of an El Nino. And the phenomenon is just one in a roulette wheel of climate factors that determine the storm season. For example, shear winds persisted in the Atlantic last summer, despite the absence of an El Nino, leading to a quiet season that baffled forecasters so completely they continued to call for a late season surge in storms even as few developed.

In fact, the long range computer modelling that now suggests a late summer El Nino is itself suspect. Long range predictions are what weather pros call "low confidence" forecast.

"The models have been totally wrong with El Nino predictions before," said Mark Malsick, S.C. Climate Office severe weather liaison. "The general (carved in Jello) rule of thumb is that the number of North Atlantic hurricanes is reduced during an El Nino; however, the hurricane threat to the South Carolina is not eliminated."

It is, in other words, way too early to say.

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