A persistent dome of high pressure has dominated the Southern Plains and lower Mississippi Valley for the past several months, shunting storm systems to the north and exacerbating the severe drought that plagues the region; indeed, its presence deprived Texas of tropical moisture from the season's first Atlantic storm, which was deflected westward across Mexico. Combined with a deep atmospheric trough that covered most of the West throughout the spring and early summer, this dome has also contributed to the flooding across the Central Rockies and Northern Plains as Pacific moisture was swept north and east along its rim.
Over the past two days, this blocking ridge has dropped further to the south, allowing a cold front to ease conditions across the Midwest; here in central Missouri, we should stay in the 80s (F) for the next couple of days before the dome inches northward once again. Meanwhile, to our south, the intense heat and drought continue, with highs above 100 degrees and no relief in sight.
A dome of high pressure over the Southern Plains is typical in mid-late summer and is partly responsible for the Southwest monsoon that brings Gulf and Pacific moisture to the Four-Corners region and the Southern Rocky Mountains. However, this year, it has been in place since late winter and shows no sign of breaking down; until it does, perhaps under assault from a potent tropical system, the drought will continue.
