Particularly dangerous situation

In weather forecasting in the United States, "particularly dangerous situation" (PDS) is wording occasionally used by the National Weather Service in their watch and warning messages to convey heightened urgency for a severe weather event that is unusually and particularly extreme and life-threatening compared to the norm for the type of event. It is used in the format "This is a particularly dangerous situation..." at the discretion of the issuing forecaster.

Source: Wikipedia — Particularly dangerous situation (CC BY-SA 4.0)