Summer Sizzles As Heat Dome Caps Most Of The U.S.

From North to South and East to West, much of the nation feels like a steam bath because of a heat dome and other principles at work in our atmosphere.

Huge amounts of warm air and moisture are trapped under a vast "heat dome," bringing record-breaking temps and heavy tropical air to many cities not familiar with extreme heat and humidity.  

The system is moving east from The Plains and Ohio Valley spreading misery to some of the nation’s most densely populated metropolitan areas.  The heat dome is expected to remain in place throughout the weekend.

A heat dome forms when high pressure develops in the upper atmosphere. This causes the air below to sink and compress because it’s top heavy. As a result, temperatures rise in the lower atmosphere.

The high pressure heat dome also pushes the jet stream and its drier, cooler air, further to the north. That cool dry air is now in Canada. The combination of mostly clear skies and the high angle of the summertime sun make it mighty hot and steamy!  

Record breaking heat index readings combined with humidity in extreme cases are ranging from 115 to 129 degrees.

The formation of the heat dome explains why conditions in places like North Dakota are similar to summer conditions in Louisiana. The major difference is that people in the Deep South know how to deal with hot weather. Those in the north do not and they are not equipped to handle extreme high temperatures and humidity.