D.C.'s mild winter: Why don't we have any snow?

Frederick County got a little dusting on our last go-around with snow, but it has been a historically snow-free winter overall.

Believe it or not, spring already officially begins in just five weeks.

But if you tell anyone around the D.C. metro area that right now, they'll tell you that at some points, spring has already sprung.

From the first day of meteorological winter, Dec. 1, temperatures have consistently averaged above normal. In fact, December of 2011 turned out to be the 6th warmest December on record.

That trend continued through the new year, when last month became the 18th warmest January in recorded history. Unsurprisingly, February is trending that way too, despite the gusty, bone-chilling conditions we experienced last weekend.

Needless to say, it has been a wacky, historically low-snow winter that some people really like and some people really don't. In fact, if we were to get no more snow this winter, 2011-12 would go down as the third least snowy winter since the National Weather Service began recording snowfall in the D.C. area.

Why is it happening, though?

There is no single reason why it has been so mild here in the Mid-Atlantic or why, on the flip side, it has been so incredibly snowy and cold in Alaska, Canada, Europe and parts of Asia. Portions of America's 49th state have reached temperatures as low as -60 this season, while a large chunk of Europe found itself in a cold snap that killed hundreds of people.

The most likely causes for what's going on are the Arctic and North Atlantic oscillations - or in layman's terms - patterns of wind and atmospheric pressure that have kept most of the bitterly cold air locked up in Arctic and sub-Arctic areas like Alaska and northern Canada.

The truth is in the numbers. In both December and January, the average temperature was well above the typical average high, and we're right on track to do the same in February.

Patterns are apt to shift, though, as we saw when flurries pushed through the region and wind chills dipped into the single digits. However, as the late-winter sun gets stronger and daylight hours get longer, any further outbreaks of Arctic air will be short-lived.

But never fear, snow lovers. The winter isn't over yet, and we've seen major snow and ice storms here as late as mid-March.