Particularly dangerous situation
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A particularly dangerous situation (PDS) is a type of enhanced wording used by the National Weather Service's Storm Prediction Center in Norman, Oklahoma on certain weather watches. It implies that there is an enhanced risk of very severe and life-threatening weather, usually a major tornado outbreak or an extreme derecho.[1] PDS watches are quite uncommon; less than 3% of watches issued by the SPC from 1996 to 2005 were PDS watches, or an average of 24 each year.[2]
PDS tornado watches are issued when there is a greater risk of strong or violent tornadoes in the watch area, in addition to significant wind and hail damage. They are usually issued when the potential exists for a major tornado outbreak. They represent about 90% of PDS watches issued.[3]
PDS severe thunderstorm watches are issued when there is a greater risk of severe wind damage capable of major structural damage (in addition to large hail and perhaps a few isolated tornadoes), usually due to a strong derecho. They are very rare (an average of only two each year[4]) as the tornado risk has to remain low enough to only warrant a severe thunderstorm watch.
[edit] References
- ^ http://www.spc.noaa.gov/faq
- ^ http://ams.confex.com/ams/23SLS/techprogram/paper_115252.htm
- ^ http://ams.confex.com/ams/23SLS/techprogram/paper_115252.htm
- ^ http://ams.confex.com/ams/23SLS/techprogram/paper_115252.htm
