A particularly dangerous situation (PDS) tag is enhanced wording first used by the Storm Prediction Center (SPC), a national guidance center of the United States National Weather Service, for tornado watches and eventually expanded to use for other severe weather watches and warnings by local NWS forecast offices. It is issued at the discretion of the forecaster composing the watch or warning and implies that there is an enhanced risk of very severe and life-threatening weather, usually a major tornado outbreak or a long-lived, extreme derecho event, but possibly another weather hazard such as an exceptional flash flood or wildfire. PDS watches are quite uncommon; less than 3% of watches issued by the SPC from 1996 to 2005 were PDS watches, or an average of 24 each year. When a PDS watch is issued, there are often more PDS watches issued for the same weather system, even on the same day during major outbreaks, so the number of days per year that a PDS watch is issued is significantly lower. Background The short history of the origin of the option of issuing a tornado watch with the enhanced PDS wording occurred during the winter of 1981–82 when the Severe Local Storms (SELS) unit transitioned to a more flexible method of issuing weather products. Ed Ferguson, Deputy Director of the National Severe Storms Forecast Center (NSSFC), suggested to Lead Forecaster Jack Hales that the guidance center could provide an opportunity to give more resolution to the tornado watch product. Hales suggested the PDS option to identify areas where, a few times each year, conditions are most likely to aid in the development of large and intense tornadoes. The first PDS tornado watch was issued by Robert H. Johns for the April 2, 1982 tornado outbreak across the southern and central Great Plains. While historically applied only to severe thunderstorm, tornado and flash flood watches (i.e., severe local storm "polygonal" events), PDS wording could theoretically be applied to other types of weather watches (such as winter storm, high wind, hurricane, or fire weather watches) when an enhanced threat for such conditions exists. These watches have generally (but not always) been issued during a high risk or an upper-end moderate risk either of severe storms from the SPC's convective outlooks or of flash flooding from the Weather Prediction Center (WPC)'s excessive rainfall outlooks. On April 24, 2011, the National Weather Service Weather Forecast