Thanks to persistent high pressure over the central U.S., the Southwest Monsoon has surged over the past week, with bands of heavy rain and thunderstorms pushing northward across the Rockies and High Plains. Some storms have been severe and a few have produced tornadoes; as sometimes occurs during the Monsoon Season, we have also experienced overnight thunderstorms along the Front Range, developing well after the effect of solar heating has vanished.
By late August, the annual Southwest Monsoon is usually beginning to wane though, last September, torrential rains produced devastating floods from Boulder northward. This year's surge of precipitation may portend more flash flooding along the Colorado Front Range; hopefully, the atmospheric dynamics, which are currently pumping copious moisture up from the Gulfs of California and Mexico, will shift before catastrophic floods reoccur.
Whether global warming is beginning to fuel a more potent Southwest Monsoon is unclear. More likely, as often occurs with hurricane seasons, atmospheric and oceanic weather patterns have aligned to augment the Monsoon over the past two years. Of course, trends are difficult to recognize or project over the short term; for example, the severe Atlantic hurricane outbreak of 2005 has been followed by rather tame hurricane seasons in that region while, in the western Pacific, numerous super-typhoons have lashed Southeast Asia.
