Cold Air Damming: The Wedge Pattern That Prolongs Pain
Cold air damming is a winter pattern in which a shallow layer of cold air is trapped against the eastern side of a mountain range and refuses to mix out, sometimes for three or four days. Along the Appalachians, forecasters call it the wedge. For weather-sensitive people it is the most misleading pattern of the year, because the surface barometer stays high and nearly flat while the weather steadily deteriorates — grey overcast, drizzle or freezing drizzle, temperatures fifteen degrees below forecast, and no obvious atmospheric event to explain why the week has been so hard.
If you keep a pressure log and have ever had a stretch of bad days that the log completely fails to account for, a wedge is one of the more likely explanations.