Also Paul K. I think Greensburg got a tornado emergency but Parkersburg did not. The tornado in Parkersburg was not easily identifiable because it was rain-wrapped. Even though Parkersburg did not receive an actual TE, the NWS in Des Moines mentioned it being rain-wrapped and that this storm was extremely dangerous and life-threatening and capable of producing strong or violent tornadoes. Those words seem to be just as serious as the word tornado emergency.
NWS in Des Moines actually has a department-specific policy to not issue Tornado Emergencies, but they did tell Craig that they were considering ending that policy on May 25 until they came up with the strongly worded warning you mentioned.
One point they raised on the phone to me was that they did not know where the tornado would track, as it appeared on radar that it could have potentially taken an even greater right turn than it did. It actually ended up occluding near the Waterloo Airport, even though the Dunkerton wedge formed only a mile or two northeast of the same exact position about fifteen minutes later (it turns out this is the one we witnessed behind the edge of the raincore from our vantage in Jamestown).
I think TE's may be overused by some stations, especially in the Southeast, but the way that, say, Norman uses them is a valid way. IMO, a TE storm should be a very rare condition for which normal safety procedures may not hold, i.e. like OKC '99 when Gary England asked residents in reasonable advance of the storm to abandon their homes for neighbors that had underground shelters, or like in Wichita '91 when police well in advance of the Andover F5 were going through trailer parks instructing residents to abandon them completely for sturdier shelter (I think this is S.O.P. for all TOR warnings now, though).
Severe thunderstorm warnings ought to have some stronger wording, too, because some people - especially in tornado alley - tend to dismiss them unless there's an outdoor event. They already have instructions to keep an eye out for possible tornadoes within those warnings on days which they are expected, but in case of rotation or sighting this can be upgraded; however, in the case of extremely destructive straight-line winds, I'm afraid not many people will heed even the stronger wording of an SVR. A derecho is often a killer storm, especially on and near lakes, and 80-90+ MPH winds can disrupt driving or make it dangerous especially for semi's. I've noted that the NWS website has some public information about derechos - maybe they could spread the information a little more by working with local forecast offices and especially news offices, and issue warnings and even watches for these very fast-moving, very destructive storms (EDIT: derecho warnings and derecho watches, that is. I think that a derecho watch could be valid especially for boaters, who may ignore an SVR or PDS SVR box but who may think twice about boating in the almost assured case of the inescapably sweeping, wide-ranged, and fast-moving path that late summer derechos exhibit).
