Preview: Glenn's Long-Range Winter Forecast | NBC 10 Philadelphia

Preview: Glenn's Long-Range Winter Forecast

This is where and how it all started...

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    NEWSLETTERS

    NBC10
    Glenn's long-range winter forecast has become the most anticipated forecast of the year in the Philadelphia area.

    Hurricane’s first of several blogs for his 2008-9 Long-Range Winter Forecast - 12th Annual.

    This all started for me in 1997.

    A very strong El Nino was developing in the tropical Pacific.
    There was an article in a magazine correlating strong El Ninos with warm winters.
    So I went on the air and predicted a very warm winter with very little snow.

    All 3 winter months (December, January, and February) made the Top Ten warmest lists in Philadelphia, and we had less than one inch of snow during the whole winter!

    It worked out so well that viewers expected me to do the same thing the next year.

    The whole thing started snowballing, and before too long, the other stations in town were making winter forecasts (often, coincidentally? the same night ours airs).

    Seasonal forecasting has come a long way in the past 15 years, but no one can predict the winter as well as we do with short-term forecasting. While we may be 90% accurate in the forecast for tomorrow, we hope to do better than 50% in the long run. That would indicate “skill” in such forecasts.

    In the past 11 years, I’m probably in the 60-70% range, depending on how strictly it’s judged.
    It’s very hard to quantify accuracy of such forecasts, partly because I’ve gotten more specific over the years. Others are more generic, so how can they be compared?

    I just hope that overall, it’s been of help to those who care about what is likely to happen in the most crucial season of the year.

    Last year turned out well, accurately predicting very little snow and above average temperatures. Some of the details were off, but the general trend was right on.

    The pressure exists now to put out a long-range winter forecast every November. 
    Frankly, there have been some years when I wish I could just pass, but that doesn’t occur in the real world.

    This year is far from a sure bet, but there are strong signs of certain things.
    Tune in Thursday night at 11 for the TV version of the forecast, and to this website for a full, more technical discussion of the reasoning behind the forecast.

    Glenn Schwartz
    11/17/08