Subsiding air underneath a persistent upper level ridge is the reason for the hot weather this month across Middle Tennessee. The 6 to 10 day outlook...shown above has much of the eastern two thirds of the U. S. with above normal temperatures through the end of the month.
Above chart showing the upper ridge that is responsible for the hot weather as dipicted at 500 millibars (18,000 feet) sprawled across the southeastern U. S. from Texas into the mid atlantic states. The upper ridge has remained well entrenched for much of June.
Above chart showing the upper ridge at 200 millibars (about 40,000 feet up in the atmosphere). Summertime upper level highs can build to great heights and often are referred to as warm anticyclones.
Above chart shows the maximum temperatures for June 21st 2010. Notice the hotter temperatures are underneath the upper level ridge. The high at Nashville was 96 degrees.
NWS NASHVILLE TN