The World’s Worst Weather

2012-10-04 21:47:15.000 – Mike Dorfman,  Summit Intern

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Mount Washington is known for having the worst weather in the world. A relatively ‘calm’ 40 mph summer day can give a taste of how much more extreme summit weather can be from valley weather. This weather happens primarily for three reasons, the summit’s prominence, its exposure and its storm tracks.

At 6,288 feet, the summit is the highest point in the northeast. Normally, wind is slowed by friction from the ground. Air that collides with the summit has not been slowed by this friction, which allows for higher wind speeds on the summit than in the valley.

As air is forced upward over the presidential range, it accelerates through what is called the Venturi Effect. Similar to when you put your finger over a garden hose, air is squeezed into a small space and accelerates. As the air rises over the mountain the ‘cap’ of the stratosphere forces flowing air into a smaller space and forces it to accelerate.

Finally, Mt Washington is known to have the wildest weather on earth because of the storm tracks which affect it. Mt Washington is at the confluence of three major storm tracks, allowing severe storms to regularly hit it. Such storms can bring winds in excess of 100 miles per hour and very high amounts of precipitation. The record 24 hour snowfall is 49.3 inches in 1969, which is over 4 feet of snow!

One of the most famous landmarks in the observatory’s existence is our extreme wind. On April 12th of 1934, a wind speed of 231 miles per hour was recorded on the summit, and this remains the highest wind speed ever recorded by man. As wind speed increases, not only do the amount of air molecules increase, but the molecules aren’t as likely to stream around an object in this wind. This therefore quadruples the force of the wind every time the speed is doubled, making the relationship between wind speed and force exerted by the wind a nonlinear one. Most people have an extremely difficult time standing in 100 mile per hour winds. When our record wind speed was recorded, stepping out of the building would have been like stepping into the center of and F4 tornado.

A 3-cup anemometer, used in some observatories, would not be accurate in the extreme icing conditions that exist on Mount Washington for most of the year. To record these extreme wind speeds, the observatory went to airplane technology, using a heated pitot anemometer. This device is essentially a heated tube with one open end which is angled into the wind. From the difference in pressure between the inside of the tube and outside of the tube, the wind speed can be determined. Even with the heated anemometer, observers have to go out constantly (every 20 minutes in extreme icing conditions) to deice the instruments.

Each winter, observers experience extreme weather on top of the highest summit in New England. To accurately record this weather, they must use specialized equipment, which has been developed and improved in the observatory’s decades of existence. Observers work hard to brave the elements and test their own abilities in such harsh weather.

Mike Dorfman,  Summit Intern