Weather patterns of Juneau Alaska and their relationship to aircraft hazards

Juneau Alaska is located on the coast of southeast Alaska between the Coast Mountain range and the Alexander Archipelago. Its dramatic terrain rises to over 1000 m, and the Juneau ice field and Taku glacier rest to its east. Juneau's weather is influenced by both moist maritime air masses and cold, dry continental air masses. The Aleutian low in the Gulf of Alaska guides storms with strong pressure gradients on to the shore, and the interaction of these storms with the precipitous terrain generates strong local flows. Dry continental air traverses the Coast Mountains to reach Juneau and arrives as strong northeast winds from density currents, known as gap flow, or from downslope windstorms from amplified mountain waves, known locally as the “Taku”. This presentation will discuss the characteristics of strong flows around Juneau, their interaction with the surrounding mountains, and how the combination can generate aviation hazards.