The Big Wind
At 4 AM on April 11, 1934, Wendell Stephenson awoke in the Mount Washington Weather Observatory to the sound of the wind ferociously gusting against the side of the building. Perched on top of New England’s highest peak, the observatory was only two years old, and several other buildings on the summit had collapsed under the weather’s beating. The clear weather of the previous afternoon had been superseded by fog, with up to a foot of rime ice forming on some of the summit buildings. The evening’s top wind speed was 136 mph, and Stephenson could tell by the wind’s shrieking that the gale was now blowing harder. His anemometer only read 105 mph, however, so he knew that ice was impeding it (mountwashington.org/about/visitor/ recordwind.php).
Stephenson pulled on his cold weather gear and headed up to the observation deck with a wooden club for clearing ice. Knocked to the ground by the wind when he opened the door, he nonetheless forced his way to the ladder, atop which the anemometer perched. Luckily, the wind blew him against the ladder as he struggled to de-ice the anemometer. After dozens of blows, it was free. Stephenson dropped the club, which blew away out of sight in the fog.
Back inside the observatory, he resumed his measurements, which in those days involved timing the number of clicks from a telegraph sounder attached to the anemometer, then adjusting for error with a corrections chart (Ibid). The wind now topped 150 mph. As the day wore on, conditions intensified. Between noon and 1:00 PM, wind speed exceeded 220 mph. Finally, at 1:21 PM, the top gust of 231 mph was recorded—the highest surface wind value ever officially recorded, anywhere in the world.
The storm then receded, stubbornly but surely. The press and scientists were astonished when they heard the news, and the anemometer, which was specially designed for Mt. Washington, was brought to Cambridge, Massachusetts for testing in a wind tunnel. The MIT laboratory confirmed its accuracy.
Why, then, on a relatively small mountain of 6,288 feet, did the strongest wind ever recorded take place? This paper will explore and explain the meteorological and geographical dynamics that led to this remarkable storm, and it will subsequently detail how such intense winds affect the geoecology of the White Mountains.
Mt. Washington is the tallest mountain in the Presidential Range of the White Mountains, themselves a range of the Appalachian Mountains that lie within New Hampshire. In addition to its wild weather, it is known for its alpine zone, which starts at a surprisingly low elevation (around 4,500 feet) for the latitude (44 degrees north). According to the criteria proposed by Larry Price in his textbook Mountains and Man, Mt. Washington only barely qualifies as a high mountain landscape (Price, 17, 1991). It displays a few features peculiar to glaciated landscapes—a couple of arêtes and cirques—has a few soil stripes and felsenmeer, which are rocks shattered by frost action, and undergoes mass wasting events such as rockfalls and debris flows in its steeper ravines. Despite New Hampshire’s nickname as “The Granite State,” the Presidential Range is actually composed of metamorphic gneisses and schists.
Darby Field first climbed the peak in 1642, only 22 years after the Pilgrims landed at Plymouth. Mt. Washington’s proximity to the megalopolis has nurtured a substantial tourism industry around the mountain. By the mid-nineteenth century, a hotel stood on the summit, and an auto road, originally built for horses, and a cog railway, the first mountain-climbing variety of its kind, opened in the 1860s. These structures, particularly the former, made the summit accessible and easily supplied, allowing scientists as well as service-industry workers to maintain permanent residence on the summit, from which they could pursue botanical and meteorological studies. The US Signal Service, a predecessor of the National Weather Service, maintained a station on the peak from 1870-1892, but forty years passed before the Mount Washington Observatory was established.
General Weather Conditions
In New England, as in all but the most southerly parts of the United States, prevailing winds blow from the west. Heating at the equator causes air to rise through convection, and the air moves northward until it sinks back to the surface at 30 degrees north. Another zone of movement called the Ferrel cell flows in the opposite direction—air rises at 60 degrees north and moves to thirty degrees north, where it sinks. Along with the coriolis effect, Ferrel cells are responsible for the westerly flow of air across the United States, which partially govern the movement of storm tracks across the country. Low pressure systems are also influenced by the Icelandic Low, an area of consistent low pressure just northeast of New England (Zielinski & Keim, 58, 2005). Nine of the country’s twelve major storm tracks consequently exit the continental US through New England as they move toward this area of low pressure (which is also why the region is especially vulnerable to air pollution). Some observers have nicknamed New England the “tailpipe” of the country (Ibid).
Though the White Mountains are small on a global scale, they are the largest mountains east of the Rockies. The Adirondacks and Green Mountains are the only significant mountain ranges between the Whites and the Rockies, and only two peaks in these smaller ranges exceed 5,000 feet. Mountains generally experience strong winds since they extend high up into the atmosphere. At altitude, air slows less from friction, and it is funneled vertically between ridges and the lower reaches of the atmosphere, forcing it to speed up to pass through the narrower space. In the White Mountains, weather systems are particularly severe because they have sailed across the continent free of obstacles for more than two thousand miles. Thus the Whites, which are aligned roughly perpendicular to west winds, bear the brunt of instability and moisture associated with low pressure systems moving toward the Icelandic Low.
Consequently, harsh weather is normal in the White Mountains. Additionally, westerly flow across the US can be zonal, which moves high and low pressure systems steadily and slowly, or meridional, when the transition between high and low pressure systems is much quicker and more violent (Zielinski & Keim, 24). Though he was unaware of the causes, Mark Twain was referring to meridional flow when he quipped, “If you don’t like New England weather, wait a minute.”
Seasonal disparities in the New England climate are substantial, for wind as well as temperature. Mt. Washington’s most gentle winds occur in August, when they average 25.1 mph; in January, the mean is 46.3 mph (www.mountwashington.org/weather/ normals.php). In the winter, the margin of the Polar Cell, which borders the Ferrel Cell to the north, moves south. Its edge, known as the Polar Front or jet stream, intensifies storms, exacerbating winter winds (Zielinski & Keim, 25).
In sum, meridional flow of weather systems can create extremely variable and severe weather around Mt. Washington, particularly in the winter, although wind speed has exceeded 100 mph in every month of the year.
The Big Wind continues......