We have experienced excessive heat over the past few days, and there is more to come again today and Tuesday as the controlling meteorological features remain in place. A massive upper level high pressure system or ridge, has been in place since last week, and the feature will strengthen even more early this week producing a gargantuan area of subsiding air across the central United States. This subsidence generates warming through the lower levels of the atmosphere. This warming due to subsidence, warm air advection out of the Southern Plains and Lower Mississippi Valley, and nearly full sunshine will produce more record or near record high temperatures through Tuesday. Enough moisture is being pulled into the four state area on those southerly winds to create some uncomfortable humidity. The combination of those middle and upper 90 degree high temperatures and relatively high dewpoint temperatures will push heat indices up to around 100 to add a bit of misery to the heat wave. There is some relief on the way, in the form of a cold front that will be moving into the region later in the day Wednesday, or Wednesday night. Temperatures should be a few degrees cooler due to some scattered to broken clouds lifted ahead of the front, on Wednesday. Therefore, high temperatures could be about five to ten degrees cooler; with many areas ending up in the lower 90s by late afternoon. However, the real cooling relief won’t be realized until later Wednesday night into Thursday, as the main body of cool, Canadian presses southeast through the four state area. There may be a few light showers around on Thursday, as moisture is lifted behind the frontal boundary. At this time, probability of precipitation is expected to be rather low on Thursday.