Stick a fork in that La Nina forecast

I spent more than a few sentences in late autumn describing what a mild and dry winter we would have in the Carolinas.

Talk about making a mistake!

Most long-range meteorologists predicted the Southeast would slide through winter with few if any problems. Those forecasts were based on the emergence of La Nina, the Pacific Ocean condition that tends to keep the South mild in winter while sending the nasty weather into the Northwest.

I remember seeing a comment posted under one of my blog entries from someone who took exception with the forecast, saying there are other conditions at work, including the North Atlantic Oscillation (NAO). That guy, whomever he was, hit the nail on the head.

I noticed an article last week on Accu-Weather's website on this topic. The point of their article: this will be a bitterly cold month in much of the United States, and their long-range specialist, Joe Bastardi, had reversed his earlier forecast of mild conditions in January and February. Their article noted that making long-range weather predictions is still tricky business, because meteorologists are still learning how all the different variables work together.

So far, this winter has been brutal in the Carolinas. December 2010 was the second-coldest in Charlotte history, and while January so far isn't among the coldest, it's well below average -- about 5 degrees below average so far.

The reason for all this cold weather is the negative NAO. Basically, that means high pressure over Greenland has created a ripple in the atmosphere that sends arctic or polar air masses racing southward into the eastern United States. On the other side of the high, the same thing is happening in Europe.

There are signs of another big blast of arctic air moving south, toward the end of next week. We'll deal with this in our next post, but it appears as if very cold air will sweep into the eastern U.S. sometime around Jan. 22 or 23. It's possible the Carolinas will miss the worst of that, but it's a sign that the negative NAO remains locked in place, at least for now.

So I'm ready to stick a fork in the forecast for a mild winter in the Southeast, because it doesn't appear as if a trend back toward less-harsh conditions will take place anytime before the beginning of February ... if it happens then.

For the record, this will be our second straight cold winter -- and the third consecutive winter with significant snowfall.

Remember that when we have three or four straight winters with no snow.