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The "particularly dangerous situation" (PDS) is a rare and urgent designation used by the U.S. National Weather Service (NWS) to highlight severe weather events that are unusually extreme and life-threatening. First introduced by the Storm Prediction Center (SPC) for tornado watches—with the inaugural PDS watch issued by Robert H. Johns during the April 2, 1982 tornado outbreak—the phrase has since been expanded to cover other hazards like flash floods, derechos, and wildfires. These watches and warnings are highly uncommon, comprising less than 3% of all watches issued between 1996 and 2005. Notable milestones include the first PDS flash flood watch issued by the NWS office in Memphis on April 24, 2011, and the first PDS red flag warnings for fire danger issued by the Reno, Nevada office in December 2017 and August 2018. However, the PDS flash flood watch category was eventually retired and replaced by the standard flood watch in 2021. Because they are reserved for the most exceptional threats, PDS alerts signal to the public and emergency managers that conditions pose an imminent, potentially catastrophic risk to life and property.