Weather: A December ForecastBy Robert Lindsay Korty
When I left for college eight years ago, the three local television stations in my home town all offered a five-day weather forecast. Shortly thereafter, one offered six, so a second then offered seven. When visiting my parents this past weekend, I learned that one is now offering a ten-day forecast. For a weatherman, the beauty of such an offer is that day ten never arrives. The tenth day of a forecast issued today will become the ninth day tomorrow and the eighth day after that. What someone predicted ten days ago for today, Dec. 2, would have been long ago forgotten by everyone except a dedicated few. If you pay close attention to very long range forecasts, you will notice how close the forecast for the tenth day is to the climatological norm. In fact, using the climatological high and low temperature, which can be looked up in an almanac, as a forecast for a day two weeks away will, on average, beat any deviation one predicts from them.
Shorter forecasts capitalize on our understanding of the physics that govern fluid flow and our ability to model it. The next three days will be cold: strong high pressure will remain anchored over the Midwest for the rest of the week. This will allow northerly winds to advect cold air over New England. Temperatures today will fall below freezing. December is off to a cold start this week, but I shall refrain from predicting how the subsequent weeks will evolve.
Today: Variably cloudy, brisk, and cold. Temperatures near freezing, falling into the upper 20s F by evening (-2 to 0°C).
Tonight: Clear and quite cold. Low 18°F (-8°C).
Wednesday: Sunny and cold. High 35°F (2°C), low 23°F (-5°C).
Thursday: Partly cloudy. High 39°F (4°C).