Effective storm-based warning strategies (Formerly P6.9)

On 1 October 2007, the National Weather Service changed its severe local storm warning strategy and verification procedures from county-based to "storm-based". Ideally, this means warnings are issued for the expected path of the hazardous weather without regard to geopolitical boundaries. Some text-based dissemination systems are still county-based, complicating efforts to provide effective storm-based warnings. Convective systems and storm clusters with varying motion vectors and rapid evolution have posed a particularly significant challenge to forecasters.

This presentation will refer to radar data from several severe storm events to provide effective ways to issue storm-based warnings with these primary goals:

* Focus on specific threat area

* Minimize false alarm area

* Minimize the number of alerts for a single county

* Anticipate rapid storm evolution and variable storm motion

* Cover all reports with as much lead time as feasible