A significant heat wave is occurring underneath an upper level high in the American southwest desert areas. During July and August, this area becomes one of the hottest areas of the planet, and today is a great example why. Particularly hot area are the valley floors, where air sinks and warms adiabatically. This is also known as compressional heating.

Perhaps the most extreme example of this is in Death Valley, where the lowest elevation in the country is recorded at 282 ft below sea level! Temperatures in this area today will be unbelievable, perhaps fatal if prolonged exposure occurs. Temperatures above 120 F will be common and it wouldn't surprise me to see some recordings above 125 F! Excessive heat warnings have been issued out of the Las Vegas NWS.