The dome of high pressure that has parked itself over the Heartland for the past two weeks shows no sign of abating. Rather than drifting off to the east, it has backed into the Southern Plains; unfortunately, those of us in the lower Missouri and Mississippi Valleys remain within its grip.
Beneath this atmospheric ridge, the air is sinking and drying out, producing excessive heat and retarding cloud formation. Storm systems are shunted along its outer rim, exacerbating drought within the dome while fueling violent weather at its periphery (as we saw in the Upper Midwest and Mid-Atlantic region last week). On the positive side, this stubborn ridge may ignite the Monoon Season across the American Southwest, pulling in moisture from both the Gulf of California and the Gulf of Mexico as clockwise winds stream along its western rim.
Those of us caught within its boundaries can expect another week of hot, dry weather, with afternoon highs near 100 degrees F. Beyond prolonging our personal discomfort, this dome of drought is taking a toll on forests and crop fields across the Heartland, stressing natural ecosystems and posing a serious challenge for farmers and ranchers. Unless relief arrives in the form of a potent Canadian front, it may take a hurricane to dislodge this ridge.