Climate of North America 101 What are the major controls on North American climate? What is the dominant flow pattern across North America in winter? How does this pattern influence North American climate?
Wind belts and jet streams associated with patterns of circulation shift seasonally as well. The polar front and polar jet stream are two of the most important controls on midlatitude North American climate.
Topography: mountain ranges influence air flow, precipitation patterns, and local climate because of elevation.
700 mb pressure patterns
Variations of the Pacific/North American pattern influence the jet stream and the winter storm track, and well as the incidence of cold outbreaks in the eastern US.
Winter 700 mb jet stream variability controls precipitation across the USA
Scale is not the same in these 2 figures
annual hydrograph for winter storm-driven regime
There is variability in the amount and timing of runoff, and well as variations of annual runoff due to natural climate variability at a variety of time scales….
Lees Ferry Streamflow, Annual Flow, Reconstructed and Observed
… as well as changed projected due to warming from anthropogenic climate change
Observed and projected conditions for the Colorado River Basin above Lees Ferry, using 11 models and 2 scenarios downscaled to the Colorado River basin (from Christensen and Lettenmaier 2007)