Tuesday, July 10, 2018

Haboob Season

The annual Southwestern Monsoon is beginning to intensify as high pressure over the Southern Plains and low pressure over the Baja region combine to sweep moisture into the Desert Southwest; some of this precipitation arrives from the Pacific Ocean and Sea of Cortez but even more is swept across Mexico from the Gulf of Mexico.

The heat and moisture ignite thunderstorms which often drop torrential rain on the parched landscape, leading to flash floods in the canyons and arroyos.  Cold downdrafts within these storms are forced outward when they strike the ground, producing gust fronts that race across the adjacent desert, picking up sand and dry soil to create massive dust storms, known as haboobs.

Often hundreds (if not thousands) of feet high and moving at 60 mph or more, these storms blind drivers, coat buildings and cars with debris and, of course, severely impact air quality.  The Southwest Monsoon, with its thunderstorms and haboobs, peaks in July and early August in Arizona and New Mexico; by mid August, its nourishing rains generally reach the Colorado Front Range and will be especially welcome after this hot, dry summer.