The only F5 tornado ever to touch down in the northernmost part of the Lone Star State tore through the Texas Panhandle on Apr. 9, 1947 leaving death and destruction in its 100-mile-long wake.Seventy-seven years ago, “tornado” was not a word weather predictors used in their forecasts. The thinking behind this unwritten rule was that it would do more harm than good to issue ominous warnings of a…