Tropical moisture, swept into the Desert Southwest by Tropical Depression Ivo (now off the Baja Peninsula), has been caught in the Southwest Monsoon flow. As a result, heavy rains are falling from southeastern California and western Arizona, northward and northeastward across the Great Basin and Colorado Plateau. Precipitation is expected to reach 2-3 inches in many areas and flash flooding is likely, especially in desert canyons and across mountainous terrain.
Checking the radar this evening, the moisture plume extends from the Sea of Cortez to southeastern Wyoming; while the heaviest rains will fall west of the Continental Divide, a few thundershowers have dropped across the Colorado Front Range, bringing more rain to our Littleton farm.
High pressure over the Southern Plains, a vital component of the monsoon flow, produced clear skies over southeastern Colorado today, pushing afternoon highs near 100 degrees F. Over the next few days, that high pressure dome is forecast to shift westward; in turn, the monsoon flow (which parallels its western rim) will shift westward as well, leaving the Front Range urban corridor with sunny, dry weather. After four days of welcome precipitation, we have little reason to complain.