A large ridge of high pressure will persist over the central U.S. promoting continued heat and humidity for the central and southern states. Well above normal temperatures are expected from the central Plains eastward to the Ohio Valley and southward to the southern Plains and lower Mississippi Valley. As the ridge expands eastward over the next few days much of the eastern third of the country will see a resurgence of the heat experienced last weekend.
A cold front moving along the top of the ridge will continue to trigger convection as it pushes through the upper Mid-West on Tuesday and into the northeastern U.S. by Wednesday evening. Given the abundance of moisture and instability available, some of the developing storms may be quite strong or even severe. In addition, scattered showers and thunderstorms are expected Tuesday and Wednesday across a very large warm sector stretching from the Great Lakes to the southeast.
This image shows the average maximum temperature from July 3 through July 7, 2012 from the North American Model forecast.