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Posted at 2:15 PM ET, 03/ 2/2011

February & December-February weather recap

By Matt Rogers

postfeb1.jpg
The December-January-February 2010-2011 period was cold relative to average winter temperatures over the last four decades (as shown above), but about average in a longer term context. The coldest and warmest decades are colored in purple and red.

The core of the 2010-2011 winter is behind us, and officially, the meteorological winter ended on Monday (Feb 28). Where has the time gone?

With a moderate to strong La Niña pattern in the tropical Pacific Ocean this winter, the outlook was for less cold and snow compared to last year. The cold start to the season challenged that view. But February brought expectations back in line with its warm and generally dry conditions. The average February temperature of 41.7F at Washington Reagan National Airport (DCA), was a healthy 3.6F above normal. The month recorded four days at or above 70 degrees, in rare company with just four other years, and surpassed only by 1976 (seven such days)

In historical context, Feb 2011 ranked 121 in a cold-to-warm ranking of 140 years (or 20th warmest on record) at DCA (data was recorded around Foggy Bottom in the District prior to the 1940s opening of Washington National). It was the warmest February since 2002 when the average temperature was 42.6F (another La Niña winter). Precipitation of 2.12" (liquid) ran the month about .51" below normal. And a paltry 0.5" of snow was recorded, tied for the 29th least snowy on record.

The February warm bounce pushed the average Dec-Feb temperature above last year's level, but DCA still managed to be 0.8F colder than normal (defined as 1971-2000) overall due to the colder-than-normal December through January. Out of 140 years of history, this year ranked right about in the middle at 73rd (last winter ranked a colder 56th place). I love to look at these values in context and what better way than to compare this winter's average temperature of 36.6F to the last thirteen decades (see above)!

The 1990s were the standout warmest winter decade for the DCA reporting station. This year averaged colder than the last four decades mean temperature levels. So if you thought it was a cold winter, it was indeed- relatively speaking.

postfeb2.jpg
The December-January-February average temperature this winter was slightly cooler than the average such temperature over the last decade.

If you look at the last ten years of DCA winters, you see a relatively consistent range of temperatures compared to the long-term historical upward trend. Our warmest recent winter was the 2007-2008 strong La Niña year, which averaged above 40F.

postfeb3.jpg
Seasonal snowfall over the last decade. Note: more snow could fall during March/April to up the 2010-2011 total (though odds are diminishing).

And wow, what a difference a year makes on the snow front. While this year's 9.9" is above the 06-07, 07-08, and 08-09 winters (take note, Walter), it is nowhere near last year's 56.1" powerhouse. February's snowfall in 2011 was just 1.5 percent of 2010's 32.1".

Major pattern blocking features drove our stronger cold weather in December and January. Those blocks broke down in February to allow for a more classic La Niña pattern to prevail. It seems as though that story will continue here in March. So, it means plenty of daily temperature swings, usually rain, and maybe a snow chance here or there. But temperatures should overall average near to or warmer-than-normal, and precipitation should average near or below normal.

National Weather Service Climate Recaps for February:

Reagan National
Dulles
Baltimore Washington International

Historical Washington, DC data provided by NOAA and Speedwell Weather.

By Matt Rogers  | March 2, 2011; 2:15 PM ET
Categories:  Latest, Local Climate, Recaps  
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