Houston's mayor said at least four people died in a severe windstorm that caused widespread damage Thursday, as the National Weather Service warned of "dangerous and life-threatening flash flooding" in eastern Texas and western Louisiana. The big picture: The NWS' Storm Prediction Center had warned of possible tornadoes and issued a high risk (Level 4 of 4) of excessive rainfall for portions of western Louisiana and eastern Texas as widespread thunderstorms struck the already-saturated...