A stubborn dome of high pressure has been sitting over the Southern Plains and Lower Mississippi Valley for the past two weeks and shows no sign of breaking down. Such atmospheric domes are characterized by sinking air which compresses, dries out and heats up as it drops. Hot sunny days with limited cloud cover result and the vegetation begins to dessicate. Furthermore, "pop-up" thunderstorms, which usually provide intermittent relief during summer heat waves, cannot develop under these conditions.
Since winds move clockwise around zones of high pressure, showers and thunderstorms that develop outside the dome are pushed along its rim, from New Mexico and Colorado across the Northern Plains and into the Upper Midwest and Northeast. Meanwhile, those of us within the dome have experienced a seemingly endless string of hot, sunny days, with highs in the upper 90s and low 100s; even the overnight lows remain in the 70s.
But the daylight is waning, the college kids are back in town and the glorious days of fall are within sight. Soon, this stubborn heat wave will be just another memory to embellish!
