* WHAT...For the Dense Fog Advisory, visibility less than half a mile in dense fog. For the Extreme Heat Watch, dangerously hot conditions with heat index values up to 106 possible. * WHERE...Portions of east central and northeast Kansas and central, north central, northeast, northwest, and west central Missouri. * WHEN...For the Dense Fog Advisory, until 10 AM CDT this morning. For the Extreme Heat Watch, from Sunday afternoon through Tuesday evening. * IMPACTS...Heat related illnesses increase significantly during extreme heat and high humidity events. Low visibility could make driving conditions hazardous.