A Comparison of Select High Risk Outlooks for Severe Weather and Excessive Rainfall

On average, the National Weather Service (NWS) Storm Prediction Center (SPC) issues about four High Risk outlooks for widespread severe thunderstorms and potentially violent tornadoes annually. In many instances, these outlooks receive widespread distribution and attention from both local and national media. As these high-end events unfold, the SPC usually issues “Particularly Dangerous Situation” Tornado Watches, that are also highly recognized by media, emergency management, and the public. The NWS Weather Prediction Center (WPC) also issues outlooks with a High RIsk category, for extreme rainfall events that can result in catastrophic flooding. The NWS, however, does not issue flood or flash flood watches using the “Particularly Dangerous Situation” wording within these High Risk situations.

This presentation will compare and contrast the meteorology and impacts associated with High Risk outlooks for severe weather versus excessive rainfall outlooks for flooding. While anecdotal, there is evidence to suggest the SPC High Risk outlooks for severe weather garner considerable notoriety compared to High Risk outlooks for excessive rainfall. This dichotomy between different hazardous weather outlook products will be explored by summarizing losses for a few select events. These comparisons may result in a greater appreciation for the potentially devastating impacts that may unfold in High Risk excessive rainfall outlooks.