A Particularly Dangerous Situation (PDS) is special wording the National Weather Service (NWS) adds to certain watches and warnings when forecasters expect a hazard well beyond the usual for that product. It is best known from Storm Prediction Center (SPC) tornado watches, where it marks rare days when forecasters have high confidence in multiple strong or violent tornadoes.
PDS watches
SPC can attach the label to both tornado and severe thunderstorm watches. An SPC study by Andrew Dean and Joseph Schaefer ties PDS tornado watches to that high confidence in multiple strong or violent tornadoes within the watch area.
The same study says PDS severe thunderstorm watches are issued for the threat of a high-end derecho with widespread wind damage. Both are uncommon. Of 3,058 tornado watches from 1996 to 2005, 216, about 7 percent, carried the label, and only 22 severe thunderstorm watches did over the same years.
PDS wording in tornado warnings
Local NWS offices use the phrase too. Under the national directive for severe weather warnings, a Tornado Warning with a CONSIDERABLE damage threat tag adds a line stating that this is a PARTICULARLY DANGEROUS SITUATION and telling people to take cover now.
NWS describes that tier as rare situations with a considerable threat to life and property from a strong, ongoing tornado. The tier above it, CATASTROPHIC, is the Tornado Emergency.
New for blizzards and ice storms
NWS Service Change Notice 26-52 set operational use of PDS wording in Blizzard Warnings and Ice Storm Warnings on or about 10/01/26. The notice reserves it for high confidence in a blizzard or ice storm of extreme and historic severity, an exceptional threat beyond the typical event.
What the label does not tell you
PDS reflects forecaster confidence in a high-end event, not a guarantee for any one place. In the 1996 to 2005 study, 44 percent of PDS tornado watches contained at least one tornado rated F2 or stronger, compared with 15 percent of other tornado watches.
That cuts both ways. Many PDS watches do not produce a strong tornado at a given town, and ordinary watches still produce strong tornadoes. Treat the label as a reason to settle shelter plans early, then follow the warnings for individual storms.