Updraft Helicity Forecasts for Targeted Impact-Based Decision Support Services
Chauncy Schultz, NOAA/NWS, Bismarck, ND
Patrick Ayd, NOAA/NWS
Convection-allowing models and the storm attribute fields that they produce have become vital forecasting tools. However, little guidance exists on the distribution of fields such as updraft speed and updraft helicity relative to model climatology, or on their association with the magnitude and coverage of severe convective hazards. An initial investigation of storm attribute fields from the Storm Prediction Center Storm-Scale Ensemble of Opportunity (SPC SSEO) in the northern plains revealed a statistically significant correlation between event-total severe weather reports and updraft helicity forecasts. This study expands that climatology to a more robust exploration of updraft helicity signatures from the SPC SSEO across the entire continental United States from January 2014 through June 2017. The results of that analysis provided forecasters with useful guidance from which targeted and enhanced impact-based decision support services were operationally provided ahead of severe thunderstorm events in 2016 and 2017. This presentation will share the results of the SPC SSEO updraft helicity analysis, discuss specific cases and lessons learned where its results were used in operations, and will share early plans to utilize machine learning methods to further leverage signals in updraft helicity output. In particular, it will be shown that 20% or greater neighborhood probabilities of updraft helicity over 100 m2/s2 from the SPC SSEO can serve as a trigger for providing enhanced messaging and decision support.