Weather Patterns Associated with Prolonged Low-Visibility Days during the Cold Season at Thule, Greenland

The topography of Greenland often acts as a barrier to atmospheric flow and synoptic scale weather systems creating a large variety of weather outcomes in high latitude locations. In the Coastal Greenland region, time periods of low visibility can be hazardous for ground and air transportation. A small number of studies have explored the seasonal variation and atmospheric conditions of low visibility at locations on the Eastern Greenland Coast. This research aims to examine the varying weather patterns associated with prolonged time periods of reduced visibility near Thule, Greenland (i.e., Northwest Greenland). Surface hourly observations from a 30-year period (1989 – 2018) for the Thule Air Base (AB) were used to identify prolonged low visibility days (i.e., having visibility of < 2 miles for at least 6 hrs.) in the cold season (December, January, February). Using the surface hourly manual and automated current weather observations/codes (99 codes), eleven weather classifications (WX Classes) were created. Composite regional weather maps were produced using prolonged low visibility days where only one WX Class occurred for all low visibility hours. This resulted in seven composite regional weather patterns (e.g., fog, blowing snow, precipitation). As examples, blowing snow days have a strong cyclone centered near northwest Greenland covering the Thule AB area; fog days have a cyclone centered over the North Atlantic Ocean and an anticyclone over Greenland; and precipitation days have a broad weak cyclone positioned just west of Greenland.