Records are falling across the American Midwest this week as the first major heat wave of the season invades our region. High pressure over the Southern Plains, combined with a high pressure dome over the Southeast, has ushered in the hot, dry air; afternoon highs should top 100 degrees F in most areas.
In part, the extreme heat reflects the dryness of the air, as Gulf of Mexico moisture is kept at bay by the blocking high across the Southeast. Dry air is more dense than humid air and is thus capable of reaching higher temperatures. Indeed, winds are from the west-southwest and it feels more like Phoenix than Miami across the Heartland.
This heat wave will be slow to break as cloudless skies permit the intense sunshine to heat up the roofs and roadways in our towns and cities; this heat radiates into the air overnight, keeping the morning low well above average. In addition, it will likely take a strong cold front to displace this high pressure ridge and none are forecast over the coming week. For now, we'll confine our outdoor activities to the early morning and evening hours, hide from the afternoon sun and dream of October.
