Summer Field Studies of Wind Variability in Denali National Park and Preserve

Glidden, D.

Field studies of wind variability were conducted at three sites in Denali National Park and Preserve during June, 1995. Comparisons were made with 1994 data from the existing Upper Ridge (UR) Rock Creek wind site (part of the Inventory and Monitoring Program of the NPS), and with other mountain sites in Rocky Mountain National Park in Colorado (RMNP) and with Mount Washington, NH. Data summarized include maximum winds, hourly pressure change, average gust factors and peak gust ratios, diurnal pressure and wind variations, and other supporting meteorological parameters. The maximum winds recorded during the June, 1995 study period were 59 MPH (26 m/s) from the southeast at Polychrome, and were associated with rapidly rising pressure. Peak gust ratios between sites were determined. Polychrome usually had higher winds, with one occurrence three times higher than that recorded at Eielson Bluff. On other occasions, maxima were quite close. Comparing average winds and directions, Polychrome generally had higher values, but not always. During some hours, Eielson could have higher averages than either Polychrome or Toklat. Diurnal pressure variations were identified at Polychrome. Average pressures begin to fall by 1400, with minima occurring between 1700-1900 hours. Pressure minima at Polychrome appear to correspond generally to average maximum winds at Eilson Bluff. It is suggested that Denali National Park develop its own capability to identify and monitor all important climatic areas within its boundaries, and that this capability should be extended (where possible) to the higher reaches of the Alaska Range and the Mount McKinley massif, where the current data base is inadequate or non-existent. It is recommended that the NPS establish three wind research sites along a north-south transect, ranging from the Eielson area in the north, through a line above 12,000 ft (3658 m) on the Alaska Range, to the Petersville area in the south. This transect may help us to better correlate subsynoptic wind, pressure and weather conditions on Mount McKinley and the Alaska Range with synoptic or regional patterns. Through instrumenting these upper reaches, and by building a site-specific data base, we may improve our ability to anticipate and understand conditions peculiar to these areas. Visitor appreciation of extemes, and air rescue operations on Mount McKinley, may also be enhanced by this program.