As this week began, a dome of high pressure was building over the Central and Southern Plains of North America. Within that dome, sinking air and light winds have pushed afternoon highs into the 90s and low 100s (F), accompanied by oppressive humidity.
Meanwhile, clockwise winds along the outer rim of that dome, combined with counterclockwise winds surrounding low pressure over Southern California, have swept moisture northward from the Gulfs of Mexico and California, fueling the Southwest Monsoon. This copious moisture has caused extensive flooding near Phoenix and produced bands of rain and thunderstorms throughout the Rocky Mountain and Wasatch corridors; indeed, this stormy pattern continues eastward across the Northern Plains (along the northern rim of the dome) and, by tomorrow, is expected to fuel thunderstorms across the Great Lakes region. This evening, storms are igniting from Kentucky to Georgia, along the southeastern edge of the high pressure dome.
As the dome drifts eastward, bringing oppressive heat to the Midwest and Southeast, the rim of storms will move in concert, dropping rain across the High Plains, Great Lakes, Upper Ohio Valley and the Mid-Atlantic region. Here along the Front Range, just west of the dome, we'll enjoy relatively mild, sunny conditions, broken by late-day monsoon thunderstorms.
