Winter Forecast 2011-2012 for the Carolinas

Last winter was our second straight winter with well below temperatures and slightly above average snowfall in the Charlotte region. We had 6.1” of snow and the temperatures were the coldest since the late 1970s. This was highlighted by the first white Christmas in charlotte in 63 years.

That storm brought snow to almost the entire state of North Carolina(see map right) and was a rare holiday treat for many long time residents of the Carolinas. This was coupled with a very cold December and January with a milder February. This Winter some the exact same ingredients that we had in place last winter are back again this winter. The first of the these climate factors is The El Nino/La Nina cycle or ENSO. Last year was a very strong La Nina and this winter we are on pace for a “double dip” La Nina. So what does the impact of ENSO mean for the Carolinas as far as snowfall?

North Atlantic Oscillation NAO

This oscillation was the main cause for so much cold air early last winter. When this index is negative we have persistent cold weather east of the Rockies. This is due to a blocking ridge of high pressure forcing cold air down into the eastern U.S. from the Arctic.

(Credit Paul Douglas)

The Analogs

Other notable climate predictors I look at include the following Arctic Oscillation(AO), Pacific-North American Pattern(PNA) and the Madden Julian Oscillation(MJO). These along with solar and lunar cycles help to determine what kind of winter we will have. Looking at these cycles and especially the ENSO phase you come up with analog forecasts. These are forecasts based on what has happened in the past. Basically what happened during the winter months in the past when we had a similar set-up in these climate predictors.

Thanks to help of fellow Meteorologist and winter forecaster Mark Johnson we have these analog forecasts based on this years set up. The years that stick out for me are 1974-76 and 2008 when we had the most similar phase of LA Nina. This mid 70s winters were also the last time we had a double dip La Nina like the one that is forecasted this winter. Much like last winter there will be early cold but a quick warm-up in the February and into the Spring. Which unfortunately could mean a very active Tornado season like we saw this year. La Nina especially has been shown to produce cool season tornado outbreaks with strong long track tornadoes across Dixie Alley. The February 2008 Super Tuesday outbreak was one of those events.