Forecast implications of regional variations in storm modes and environments that produce significant tornadoes in the United States
Each tornadic storm's convective mode is classified as a discrete supercell, MCS/QLCSs, or other. Discrete supercells and MCS/QLCSs are further subdivided into non-mergers and mergers based on whether they were isolated cells or merged with another cell or line within one hour of tornadogenesis. Interannual, seasonal and diurnal variations associated with each storm type and variability in storm structures (i.e., CL, HP, LP, or mini for supercells and TS, PS, LS, TS-AS, QS-BB, or other QLCSs for MCSs) and forcing mechanisms (i.e., dryline, outflow boundary, prefrontal troughs or confluence zones, cold front, warm front, or other) for each storm type will be investigated. In addition, variations in tornado warning lead-times (using Iowa State's archive of unofficial NWS Storm Based Warning Verifications) will be analyzed preliminarily to help forecasters and emergency managers better understand tornadic threats and warning capabilities for their respective regions when they experience specific storm modes. Finally, composite synoptic conditions for significant and outbreak (five or more EF2 tornadoes or greater) tornado events will be compared for each region if time permits.