Wednesday, December 12, 2012
Weather columnist Kevin Myatt: Despite balmy start, winter likely to get quite icy
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I've been insisting that winter 2012-13 would be nothing like 2011-12, the second warmest winter in a century of weather records at Roanoke.
So far, it's been warmer. Much warmer.
The first 10 days of meteorological winter (began Dec. 1) have averaged 51.7 degrees at Roanoke, which is almost 8 degrees warmer than the first 10 days of last December.
Dec. 1-10 was almost 20 degrees warmer than the same period in 2010, which became our fifth coldest December on record, and about 10 degrees warmer than the same period in 2009, which preceded by 9 days the first of three big snows in the 2009-10 winter.
Roanoke's normal average temperature for the first 10 days of December, based on the 1981-2010 period used to calculate climate norms, is 41.2 degrees. This month's first 10 days averaged 10.5 degrees above normal. The Southeast Regional Climate Center reports it's the third warmest first 10 days of December in the modern era of Roanoke weather records, dating to 1947 when data at the current airport site began.
After colder than normal weather in October and November, December's weather pattern was dominated at its outset by strong low-pressure off the coast of the Pacific Northwest, which has circulated mild Pacific air into much of the country and kept Arctic air bottled up to our north in Canada.
But, contrary to the impatient expectations of some snow lovers, the first 10 days of December often don't have much correlation to what happens through the entirety of the season.
Indeed, two of our three snowiest winters - 1959-60 and 1986-87 - had no snowfall at all in Roanoke before the end of December.
Unlike last winter, there is dense snowpack covering Canada, and thick cold air building above it just waiting for an excuse to pour southward.
It is starting to do just that in punches. One such punch of cold air smacked the central U.S. these past few days, with 10 inches of snow in Minneapolis, single-digit temperatures as far south as the Oklahoma Panhandle, and a skiff of snow in some Dallas suburbs.
The same cold front pushed through here late Monday, and a modified version of that same air mass has temporarily dropped our temperatures back to near December norms with highs in the 40s and lows in the 20s to low 30s.
We'll bounce back to milder temperatures by the weekend, maybe not quite as mild as the mid-60s to low 70s we've seen many days since the month began.
But it appears there will be an even larger punch of Arctic air next week aimed more directly at us.
So I maintain my insistence that this winter will not be as warm as last winter when we look back on it after Feb. 28, despite its much warmer start.
There's just too much frigid air building north of us. It will not be denied for three months just because it has been for 10 days.
Weather Journal appears on Wednesdays.