What Winter Will Bring

What Winter Will Bring:

An Amateur Weatherman’s Forecast

11/2/2008

Kenneth Burchfiel

If December is the most wonderful time of the year, November has to be the most stressful—for meteorologists, at least. This is the season of winter forecasts, where amateurs and professionals alike try to predict how much snow and cold the coming months will bring.

Before I made my own forecast, I thought it best to consult an expert in the field: Matt Ross, a contributor to the Washington Post weather blog Capitalweather.com. As he explained, predicting an entire winter season isn’t easy.

“In a medium [or] long range outlook, the best you can hope for is painting a general idea,” he said. “The more specific you get the higher likelihood of a [bust].”

Ross likes to use “analogs,” or years with similar spring, summer and fall weather, in making his predictions. He cited 1917-1918, 1943-1944 and 1996-1997 as some seasons that might match ours. His second major tool? A strange realm of weather data called the El Niño Southern Oscillation, or ENSO for short. For December, at least, that factor seems to be going the snow fans’ way.

“The strongest signal is for a cold [December] which is pretty typical in very week La Ninas following a stronger La Nina like we had last winter,” Ross said. “La Nina,” the opposite of El Niño, refers to the cooler-than-normal Pacific Ocean temperatures that we saw last winter.

Of course, predicting the weather takes more than analogs and the Pacific Ocean. Ross also cited temperature trends, precipitation amounts and hurricane statistics as vital factors in his forecasts. Needless to say, predicting the winter takes more than a thermometer and a good imagination.

Taking Ross’s personal forecast and advice into account, I set off to predict the kind of snowfall McLean would see for the 2008 season. First, I had to consider our region’s climate. According to a map put out by the Baltimore/Washington National Weather Service, McLean receives 22 inches of snow in an average season.

The problem is, Mother Nature has underperformed in the last few years; my records for the 2007-2008 area indicated only 8.3 inches of the white stuff and two school closings. Besides, with the District’s urban heat effect and the decrease in moisture the Shenandoah Mountains contribute to, we receive only a fraction of the snow areas further west get. (Some parts of western Maryland can expect over 100 inches per year, for example.) And with global warming looking increasingly certain, it’s hard to say how many more “normal” 23-inch winters we’ll see.

The good news for snow fans, however, is what happened in October. 13 out of Washington’s last October days had lows below average, according to Accuweather.com, and much of the Northeast saw three to twelve inches of snow. (I even got to throw a snowball during a college visit in New York.) Though day-by-day conditions can’t predict a season’s worth of weather, students hoping for school cancellations can take heart in our recent cold spell.

In the end, I decided to err on the optimistic side. Like Ross, I predict a cold December, but also feel that we’ll get a minor snow event during the holiday season.

While Ross forecasts warmer temperatures for January and February, I think that we’ll see an even mix of cold streaks and heat waves—resulting in average temperatures and a good amount of snow. We’ve had some interesting March weather in the last few years, so I feel confident calling for a winter weather event in the early part of that month.

As far as numbers go, I think the McLean area will experience five to seven snow events this year—with the bulk of those occurring in January and February. 21 inches of snow seems like a reasonable guess, and though it’s hard to forecast school closings, I think we’ll have at least three snow days by the time March rolls around.

Winter forecasting isn’t easy, and I’ll surely be proven wrong on parts of my forecast. Then again, it never hurts to hope for snow. As Ross said, “Warm dry winters are awful.”

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