Two flavors of drought in the Pacific Northwest: recent examples

In common with the rest of the West, the Pacific Northwest receives most of its precipitation in the October-March period. Two distinct types of drought occur: winters with low snowpack, either because of unusually low precipitation or unusually high temperatures, and exceptionally dry summers. The summers of 2003 and 2004 exemplified the latter type of drought, while 2005 exemplified the former. The two flavors of drought have different impacts on water-dependent sectors, including municipal water supply, agriculture, forest ecosystem health and wildfire. Owing to the lead time afforded by the low-snow winter type of drought, combined with the skill of seasonal forecasts in the winter, the predictability of the two types of droughts is substantially different.