Upper level high pressure will continue to hold over the southern plains today. Very warm temperatures and high humidity will once again result in heat index values between 105 and 110 degrees across much of eastern Oklahoma, northwest and west central Arkansas. A heat advisory will be in effect for these locations from 1 pm to 9 PM this evening. The airmass will shift a little by the weekend, resulting in slightly cooler temperatures across the area. Low end thunderstorm chances will return over the weekend for parts of the area in conjunction with an approaching upper level wave and frontal boundary. Upper level high pressure will strengthen some for the first part of the work week that will yield dry conditions and slightly warmer temperatures.