AccuWeather.com

By Kristina Pydynowski, Senior Meteorologist

Jul 18, 2010; 10:06 AM ET

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The dome of heat baking the Southwest and southern Plains will become situated over the South later this week. Not only will temperatures rise across the South, but cooling thunderstorm activity will also get suppressed.

The dome of heat is actually a large area of high pressure. Underneath that high, temperatures are on their way to sizzling values across the Southwest and southern Plains this afternoon. The same will occur on Monday.

Highs this afternoon and Monday will approach or crack the 110-degree mark in Phoenix and Las Vegas. Temperatures will exceed 100 degrees both days in Fresno, Calif., El Paso, Texas, and Dodge City, Kan.

The heat has also expanded to Denver, which set a record high on Saturday when temperatures soared to 102 degrees. That marked the city's first 100-degree reading since Aug. 2, 2008.

Residents who must endure the blazing heat are urged to follow preventive measures to safeguard against heat-related illnesses.

Later in the week, both the heat dome from the Southwest and the Bermuda high from the western Atlantic will take up residence over the South.

The combination of the two areas of high pressure will cause temperatures to approach the century mark across most of the South. This includes Raleigh, N.C., Augusta, Ga., and Montgomery, Ala.

The temperatures forecast for later this week are not much greater than highs that the South will record in the short term. The main difference is that the heat dome later in the week should also work to suppress the development of thunderstorms.

The natural tendency of thunderstorms is to provide brief cooling in their wake. For example, a thunderstorm Saturday afternoon in Jackson, Miss., caused temperatures to fall from 89 degrees to 78 degrees in one hour.

Worsening the situation is that high humidity will remain present across the South later in the week, causing AccuWeather.com RealFeel® temperatures to exceed actual temperatures.

It should be noted that not all of the South will become free of thunderstorms. A persistent flow of moisture should keep South Florida, including Miami, unsettled.

While the high should suppress thunderstorm development across the South, the opposite will take place over the Four Corners region. An influx of moisture is expected to increase thunderstorm activity later this week.

The additional cloud cover should also slightly ease the extreme heat in Phoenix and Albuquerque.

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