Denali Weather - Part I: High Winds

Mount Denali is located in a region that scientists refer to as a subpolar low. In this space, arctic air moving from the north converges with warmer air moving from the south at a latitude of 60 degrees (Denali is located at 63 degrees). This convergence creates a belt of unstable weather at this latitude.

Associated with the subpolar low is a semi-permanent area of low pressure known as the Aleutian Low, located in the vicinity of the Aleutian Islands. Weather systems generated or passing through the Aleutian Low often take a straight path for the Alaska Ranges and hit Mt. Denali with little warning. Mt. Denali also has a reputation for streaky weather with long periods of continuous bad weather or more rarely, long periods of good weather. This explains why inexperienced, clueless climbers may reach the summit while veteran climbers die on its slopes. As a result of its proximity to the Aleutian Low, the weather on Denali is unlike the weather on any other major mountain in the world. Extreme cold is another hallmark of Denali’s weather and temperatures routinely fall to -40 F (-40 C). Unfamiliarity with Denali's weather is an underlying cause of many accidents. Weather patterns generally fall under the following categories: High Winds; Low Pressure Systems from the Gulf of Alaska; Low Level Moisture; and Good Weather. In this section, we will focus on "HIGH WINDS."

HIGH WINDS. Mt. Denali undergoes long periods of clear skies and high winds, and these conditions are most often seen during early part of the climbing season (which is the time period for my expedition, May 5th through may 26th). During these periods, many of the mountain slopes are swept clean of snow leaving behind solid blue ice and testing the cramponing skills of even the most experienced climbers. Denali Pass and the upper part of the West Rib are especially notorious sites for accidents when these conditions occur. During such weather, many climbers are lulled by the clear skies into going for the summit. However, these winds routinely exceed 100 mph and have been known to pick climbers up and throw them down the slopes. Windstorms often come with little if any warning and are thus amongst the most feared weather patterns on the mountain. The first signs of increasing high winds are the appearance of lenticular cloud caps over the summit (see picture to left). Many of the accidents in 1992, Denali’s deadliest year, occurred during such a weather pattern.