Particularly dangerous situation

In weather forecasting in the United States, "particularly dangerous situation" (PDS) is the wording used by the National Weather Service to convey special urgency in watch or warning messages for unusually extreme and life-threatening severe weather. It is used in the format "This is a particularly dangerous situation..." at the discretion of the issuing forecaster. A watch or warning bearing the phrase is referred to as a PDS watch or PDS warning.

First used by the Storm Prediction Center (SPC), a national guidance center of the National Weather Service, for tornado watches, the phrase was later applied to other severe weather watches and warnings by the agency's regional forecast offices. It is most commonly used for major tornado outbreaks or long-lived, extreme derecho events, and has been used for non-convective weather hazards such as exceptional flash flooding, or a wildfire.^[1][2]

PDS watches and warnings are uncommon. From 1996 to 2005, the SPC issued an average of 24 per year, less than 3% of all watches.^[3] 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.