El Nino Could Complicate Winter Forecast

The National Oceanic Atmospheric Administration (NOAA) has released its forecast for the 2012-2013 winter season, which includes the months of December, January and February.

For two straight years, we've seen La Nina conditions play a role in influencing winter weather in some regions of the country.

Over the summer, there were signs that El Nino may play a role in the weather this winter. The El Nino event has failed to develop significantly, leaving forecasters with a challenging forecast for the upcoming winter.

"The science behind seasonal prediction is in its infancy," said Mike Halpert, deputy director of NOAA's Climate Prediction Center. "Despite recent advances, this year's winter outlook has been difficult."

Halpert added that the trend toward and then away from El Nino conditions is unique. "We really haven't seen it before. When we reach a certain threshold by August or September, we always proceed into El Nino," said Halpert. "It is incredibly unique in 60 years of data, which is a relatively small sample size."

Of course, there are other climate influences that can play a significant role in the winter such as the North Atlantic Oscillation (NAO), which if it stays in its negative phase for long periods of time can bring cold and snow to the eastern states. However, this type of short-term climate influence cannot be forecast more than a week or two in advance.

The Weather Channel's Senior Meteorologist Stu Ostro  reinforces this point, “El Nino and La Nina can play a key role in winter weather patterns in North America, but their importance can also be overstated, and in each of the past three winters other factors have overwhelmed their influence.”

Above-average warmth is expected this winter from the Rockies to the Plains states. 

Only a small portion of the country, Florida, is forecast to see temperatures stay mostly below average. This is based on the possibility of early-season weak El Nino conditions.

States from the Great Lakes to the Northeast and Southeast have equal chances of seeing below, above or near-average temperatures this winter.