(St. George, UT)  –  An excessive heat warning goes into effect today for Saint George with a red flag warning for other parts of southern Utah.  Both warnings will last through tomorrow night with high temperatures expected to get near 110 through the first half of the weekend.  Forecasters with the National Weather Service say isolated thunderstorms tomorrow could whip up high wind speeds along with lightning strikes.  A slight chance of thundershowers remains in the forecast for much of the first part of next week. Â