Verification of Proxy Severe Weather Reports from Updraft Helicity

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Thursday, 6 February 2014: 2:00 PM
Room C201 (The Georgia World Congress Center )
Mallory Paige Row, Valparaiso University, Valparaiso, IN; and J. Correia Jr.

Data collected from the operational Storm Scale Ensemble of Opportunity (SSEO) run during the Hazardous Weather Testbed (HWT) is used to create proxy storm reports derived from updraft helicity (UH) track objects. Daily probabilistic forecasts are created from the model reports allowing for a direct comparison to the observed storm reports for that day. The forecasts will be verified at various thresholds (5%, 10%, 15%, etc.). Previous findings from verifying the 2012 forecasts at the 15% threshold revealed two distinct groups amongst the members of the SSEO. One group showed tendencies to overforecast (bias > 1), while the other members showed tendencies to underforecast (bias < 1). The ensemble mean had a bias near 1 and exhibits the best skill (highest CSI). In 2012, a majority of the days at the verifying threshold took place in March to August. The ensemble mean showed better skill in the March through June, while July and August showed a less skill. Further look into verification will be looked at by using reliability diagrams, as well examining the role the individual members play in maximizing the ensemble skill.