Here are the maximum wind gusts (mph) reported at our region's three airports for each of these events:
Winter Storm Date BWI IAD DCA
Draco Dec 22 44 51 43
Euclid Dec 27 46 46 45
Freyr Dec 30 46 47 49
It is certainly unusual to experience three Advisory-level wind storms in the space of a single week. But the series testifies to the ferocity of this season's early winter storms, and the overall pattern of a very energetic jet stream.
In each case, the winds were generated on the back side of a retreating mid-latitude cyclone (low pressure region). Draco was a powerful storm that generated a blizzard over the Great Lakes, then moved over interior New England. Euclid was a Nor'easter (coastal low), as was Freyr.
As each storm moved out of our region (to the northeast), it intensified - meaning the central pressure dropped. At the same time, a cell of strong high pressure approached from the west. The difference in surface pressure between each low and its high - called the pressure gradient - determines wind strength. The gradient became very strong for several hours over the Mid Atlantic during each of these weather systems. An example of this is shown on the surface weather map for Winter Storm Draco:
|Surface weather map December 22, 2012 showing Draco's pressure gradient. Adapted from Unisys Corp|