Tuesday, July 19, 2011

May in July

Were it not for the high temperatures and the season's first crop of prairie sunflowers, one would think it is May along the Front Range of Colorado. Due to a chilly spring, which delayed melting of the winter snowpack, and to the recent monsoon rains, the South Platte and its tributaries are bank-full and greenery dominates the landscape, usually dull brown by late July.

The monsoon thunderstorms, firing up again this evening, are gifts of the high pressure dome that has brought drought and scorching temperatures to West Texas and the Southern Plains. Moisture from the Gulf of Mexico and the Gulf of California is swept northward between this atmospheric dome, with its clockwise winds, and the seasonal low over southeastern California, which produces a counterclockwise flow. A swath of monsoon thunderstorms, drifting NNE, generally develops by late June in the Desert Southwest and peaks in Colorado by August; needless to say, we are well ahead of schedule this year.

As often occurs with weather patterns, one region's bonanza comes at the expense of another geographical area. This summer's May-like landscape along the Colorado Front Range is directly tied to the record heat and drought that has plagued our neighbors to the southeast.