Week begins with excessive heat and severe weather

(TULSA, Okla.) Excessive heat Monday followed by the threat of strong to severe thunderstorms Monday evening are the main forecast concerns. Afternoon dew point values Monday are expected to rise to oppressive levels, in the upper 70s to lower 80s, across much of northeast Oklahoma and the Arkansas river valley, with only slightly lower dew points across the rest of the forecast area. With temperatures warming into the low to mid 90s across much of the area, the result will be afternoon heat index values ranging from 105 to 113, except a bit lower in far northwest Arkansas. Thus NWS has issued an excessive heat warning for parts of northeast Oklahoma and also the Arkansas river valley, with a heat advisory for the rest of eastern Oklahoma. The Excessive Heat Warning is in effect from noon to 8 PM CDT Monday. HEAT INDEX: Afternoon heat index values from 110 to 113 degrees expected. TEMPERATURE: Low to mid 90s. IMPACTS: The combination of hot temperatures and high humidity will create a dangerous situation in which heat illnesses are possible. As a cold front enters the area late Monday afternoon or early evening, strong to severe thunderstorms are expected to develop near the front given very strong instability, with large hail and damaging winds being the main severe weather hazards. The severe threat will likely diminish after midnight as the storms move into the southern part of the forecast area and weaken some. Shower and thunderstorm chances may persist Tuesday and Wednesday across southern parts of the forecast area, with cooler and drier air to the north providing some welcome relief from the very humid conditions we have seen recently. Another frontal boundary will move into the area by Friday night and Saturday bringing additional chances of showers and thunderstorms, and keeping temperatures a few degrees below the seasonal normals. Monday Mostly sunny, with a high near 94. Heat index values as high as 110. South wind 10 to 15 mph, with gusts as high as 20 mph. Monday Night Showers and thunderstorms likely, mainly before 1am. Mostly cloudy, with a low around 68. South wind 5 to 10 mph becoming north in the evening. Chance of precipitation is 70%. New rainfall amounts between three quarters and one inch possible. Tuesday Partly sunny, with a high near 82. Northeast wind around 5 mph. Tuesday Night Partly cloudy, with a low around 62. Northeast wind around 5 mph. Wednesday Sunny, with a high near 85. Northeast wind around 5 mph. Wednesday Night Mostly clear, with a low around 65. East wind around 5 mph. Thursday Mostly sunny, with a high near 88. South wind 5 to 10 mph. Thursday Night Partly cloudy, with a low around 70. South wind around 5 mph. Friday Mostly sunny, with a high near 90. South wind around 10 mph. Friday Night A 30 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 68. South wind 5 to 10 mph becoming east after midnight. Saturday A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 83. Northeast wind 5 to 10 mph. Saturday Night A 20 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 67. Northeast wind 5 to 10 mph. Sunday A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 82. Northeast wind around 5 mph.