The strongest heat dome on the planet right now is sitting over Tennessee. Not the Sahara. Not the Middle East. Tennessee. Heat makes air swell. Over Tennessee the halfway point of the atmosphere is 19,665 feet up, higher than anywhere else on Earth. Nashville hit 100 on September 15. In 153 years of records it has only been this hot this late one other time. The dome starts shifting this weekend. I'll tell you when a cold front finally breaks it.