Answer is surprising
I don’t know about you, but I thought that this past (meteorological) winter, although not particularly snowy around here, was brutally windy on many days, perhaps more so than in many years. The basis for Mother Nature’s rampage was well described by Jason Samenow in a recent post. But perceptions are often wrong, particular when it comes to the weather, so I decided to do a little research. Was I right or am I just getting older so that I can’t take those “hold-your-hat-down-days” any more?
According to the National Climatic Data Center (NCDC), the average December wind speed at Reagan National Airport (DCA), for example, is 9.4 mph. As depicted in the graphs above the National Weather Service (NWS) reports that the December 2010 average was 10.8 mph. There were 9 days with average wind speeds of 15 mph or more and one with an average of 20 mph or more (December 27th, the day after the “Boxing Day” blizzard that clobbered the Northeast and gave us little more than flurries). There were 25 days with peak gusts of 20 mph or more and 19 with peak gusts of 25 mph or more. The peak gust for the entire month was 55 mph on the 27th.
So far so good; December was about 15% windier than normal at DCA by my calculations, at least based on average wind speeds. And as you can see above, the same held true at the other two major reporting stations, with Dulles International Airport (IAD) showing the greatest departure--a whopping 39% above average. (I try to avoid the word “normal.”) The December 2010 average wind speed at Baltimore-Washington International Airport (BWI barely exceeded the long-term average, however.
During January, the atmosphere seemed to calm down--or maybe “reload” is the better word. Again, according to the NCDC, the average January wind speed at DCA is 10.0 mph but the NWS reports that in January 2011, DCA’s average was only 8.4 mph. There was only one day (the 9th) with an average wind speed of 15 mph or more, none with an average of 20 mph or more. However, there were 23 days with peak gusts of 20 mph or more and 14 with 25 mph or more. The month’s peak gust was 41 mph, on both the 12th and the 26th.
Despite some gusty days, January, then, was considerably more tranquil in these parts than December was, with DCA about 16% less windy than average and the other reporting stations showing similar departures.
February reverted to much more turbulent weather, with frequent bouts of tropical storm force winds, but for different reasons than in December. The average February wind speed at DCA is 10.3 mph, third highest of the year, but surprisingly, February 2011 was below average in two of the three reporting stations and barely above average at Dulles (IAD) with a tentative average of 8.7 mph vs the “normal” of 8.6 mph. There were only four days with average wind speeds of 15 mph or more and just one--the 19th--with an average of 20 mph or more.
Despite the low average wind speeds, February’s winds did show considerable muscle. Peak wind gusts exceeded 20 mph on 21 days and exceeded 25 mph on 17 days, almost as many as December, perceived by many as the windiest month of the entire winter. Perhaps a more revealing statistic is that February had 6 days with wind gusts of 40 mph or more (December had only four) and four days with gusts exceeding 45 mph (December had only three). Even January, the least windy month this winter, on average, had six days with gusts exceeding 40 mph. February’s peak gust was 58 mph on the 25th.
All in all, then, was it a windier (meteorological) winter than average? Statistically, no, since two of the three months had average wind speeds below normal (at least for DCA and BWI). Personally, I would say yes, based on the relatively high number of days with winds approaching or exceeding warning criteria. What do you think?
While on the subject of winds, following are a couple of historical notes, particularly for you weather trivia buffs, about how winds are (and used to be) represented and described:
Although on today’s weather maps, a wind pennant or barb faces into the direction from which the wind is blowing (so that the barb faces east when there’s an east wind), I knew it wasn’t always that way. Verifying this was a little tricky, but I did find an obscure phrase indicating that over 100 years ago, wind barbs faced downwind. Still not satisfied, I looked at the weather map for March 12, 1888, when the famous “Blizzard of ‘88” was roaring in the Northeast. Sure enough, the wind barbs were generally facing anywhere between southwest (a northeast wind) and southeast (a northwest wind).
Later I found that it was not over 100 years ago that this change occurred because U.S. weather maps as late as 1940 still showed wind barbs facing downwind. I believe, then, that the change to the current convention occurred on August 1, 1941, when many aspects of the weather map station model were all changed at the same time.
Aside from the way winds are depicted differently on weather maps today is the way changing winds are described today. Not long ago, when winds shifted from the east, to the northeast, and finally to the northwest, such as when a storm center passes by to the east, it was said that the winds were “backing,” a somewhat archaic term today. Furthermore, if a storm passed by to the west causing winds to change, say, from a southeast to a southwest direction, we were said to have “veering” winds, also archaic today. Currently, weathercasters seem just to prefer the terms “changing” or “shifting.”
What about the strongest wind ever recorded by a surface anemometer? It was long regarded as 231 mph at the Mt. Washington, New Hampshire weather station on April 12, 1934. Over a year ago, the World Meteorological Organization claimed that this record had been broken in 1996 during an Australian cyclone (a hurricane). But now, it appears that that claim has been discredited.
And last but not least, the strongest winds in our entire solar system are thought to be on the planet Neptune, where NASA has recorded winds over 1500 mph. That would definitely be a “hold-your-hat-down-day!”