Kevin Myatt is The Roanoke Times' weather columnist.

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Once merrily on its way to being one of the warmest on record in this region, Winter 2006-07 is suddenly making a sharp turn.

The cold weather ahead in the next few weeks may at times be some of the most severe we have seen in a decade or more.

There's no guarantee that copious amounts of snow and ice will accompany any of the upcoming shots of Arctic air.

A series of weak systems moving southeast out of Canada, the first of which arrives tonight, could kick up some light snow now and then. And we will have to watch any system moving through the southern U.S. to see if it can throw some moisture back this way. There may be some risk of this around Sunday or Monday.

But for now, there's no obvious winter storm threat on the horizon, and there's even a moderate chance that the upcoming cold spell will be mostly dry.

A sharp blast of cold will arrive Thursday and Friday. We will probably see nighttime temperatures drop into the teens in many areas, maybe lower than that in sheltered valleys.

Another cold blast arrives early next week, with others lined up late next week and into the week after that. Each new shot of Arctic air is likely to be a little stronger than the one before.

Between the individual shots of Arctic air, temperatures will be near normal, with highs in the 40s and lows in the 20s. But frigid northwest winds will accompany each new Arctic cold front. In a winter that started with shorts and short sleeves, that will feel downright numbing.

The weather pattern developing is, quite literally, the polar opposite of what we saw in late December and early January.

Back when it was warm, a strong low-pressure system high in the atmosphere off the West Coast, rotating counterclockwise, continually pumped mild air from the Pacific Ocean across the United States.

That strong low has been replaced by a strengthening high-pressure system. The high-pressure system, rotating clockwise, is grabbing gobs of extremely cold air from Siberia and around the North Pole and slinging it southward across snow-covered Canada toward the eastern United States.

There is no sign that this overall weather pattern will change significantly through at least the first week of February, and likely beyond.

It is quite likely that by Feb. 7, Roanoke will have had at least a day or two with lows below 10 degrees. We've only been that cold one day since 2000, and scarcely since the cold and snowy winter of 1996.

In more outlying areas, some temperatures below zero are certainly not out of the question when the more severe Arctic air shots arrive.

The frigid nights ahead would be made more colder if there were any snow cover at all on the ground, even a dusting.

Whether we get that snow is a matter of the particular positioning and timing of weather features that will have to be discerned day by day, system by system.

Most of this projected severe Arctic chill is still several days to a few weeks away. There is still some chance that the pattern will be altered enough to make the cold less severe than computer forecast models are showing. Some of those models, though, are depicting cold even more severe than I have described.

But I certainly think it's safe to say that the winter's early warmth will soon be a memory in deep freeze.