A Climatological Study of the Prominent Winds at Mount Washington, New Hampshire

Extreme winds (e.g., >100 mph) occur frequently on the summit of Mount Washington, New Hampshire (44°16'N, 71°18'W, 1914 m ASL), which has given the mountain and the Mount Washington Observatory much attention over the last 80 years of continuous weather observations. Understanding the atmospheric patterns responsible for severe winds on Mount Washington would be beneficial in forecasting future extreme wind events on mountainous terrain. This study begins with the methods and instruments used by MWO observers to measure wind. Then, a climatological analysis of the Mount Washington wind record since 1932 is presented.

The anemometers used at the summit have been custom-made to withstand heavy icing conditions combined with hurricane force winds. The anemometer type has progressed from a custom made heated anemometer constructed by the Mann Instrument Company in the 1930s to heated pitot tube static anemometers that have been used since 1946. To keep the anemometers free of rime and glaze ice accretion, heating elements in the anemometers are supplemented with manual deicing from an observer. During the most severe icing events, observers manually deice multiple times each hour to ensure accurate measurements of wind speed.

Observational and reanalysis data were used to examine the synoptic scale conditions that produce extreme wind events. Monthly, seasonal and annual averages of wind speed and direction were computed from hourly wind observations to assess climatological trends. The wind speed and direction time series were compared with large-scale atmospheric circulation patterns (e.g., the Arctic Oscillation) to identify the dominant patterns associated with wind on Mount Washington.