The new Tornado Watch for parts of AL, FL, & a small part of MS is a Particularly Dangerous Situation (PDS) Tornado Watch. Many folks are not quite sure what that means. From the NOAA Storm Prediction Center’s FAQ, here’s the definition…
“2.7 I noticed the wording “THIS IS A PARTICULARLY DANGEROUS SITUATION” in some of your watches. What does this mean? What is the criteria for a PDS watch?
The “Particularly Dangerous Situation” wording is used in Tornado Watches for rare situations when long-lived intense tornadoes are likely. This enhanced wording may also accompany Severe Thunderstorm Watches for widespread significant severe events, usually produced by exceptionally intense derechos. PDS watches are issued, when in the opinion of the forecaster, the likelihood of significant events is boosted by very volatile atmospheric conditions. Usually this decision is based on a number of atmospheric clues and parameters, so the decision to issue a PDS watch is subjective with no hard criteria. However, the SPC goal is to have 3 out of every 4 PDS Tornado Watches verifying with multiple intense tornadoes. PDS watches are most often issued with a High risk in Day 1 Convective Outlooks.”
All watches, regardless of whether they’re the “typical’ Severe Thunderstorm or Tornado Watch, are something you should watch very carefully, but when a PDS watch is issued, a very active severe weather episode is expected with large hail, strong damaging straight line winds, strong to violent (EF-2+) tornadoes and, last but not least, flash flooding along with dangerous lightning are expected. Considering this PDS Tornado Watch is going into the overnight hours, make sure you have at least three ways of receiving warnings, your NOAA weather radio has fresh batteries and is set on standby, your shelter precautions are in place, and you stay very weather aware by following official sources of potentially life saving information. At night, tornadoes are often difficult to impossible to see…so if you’re in a warning, please take shelter immediately. Lastly, follow @NWSSPC, @NWSBirmingham, @NWSMobile, @NWSTallahassee on Twitter and the broadcast meteorologists/media outlets of your choice.
Stay weather aware and stay safe!