Polygon Warnings The Sharp Focus on Service The Sharp Focus on Service NWS Partners’ Workshop Silver Spring, MD June, 2006

Polygon Watch and Warning Team Polygon Eliminates False Alarm for this Area Goal – Improving Warning Service

Polygon Watch and Warning Team Review - WFO Case Study During two convective seasons, one CR WFO issued 46 tornado warnings covering: –38,280 square miles –Included 595 towns Utilizing the polygon approach, the polygons covered: –10,374 square miles –Included 169 towns If the polygon approach were in place, when compared with the county approach: –Reduction in total area warned - 27,906 square miles –Reduction in total number of towns warned a reduction of 72%!

Polygon Watch and Warning Team Review – 2005 Case Study April through mid June 2005: an SR WFO issued 52 convective warnings covering: –41,733 square miles –Included 636 towns Utilizing the polygon approach, the polygons covered: –11,291 square miles –Included 198 towns Number of events which occurred outside the polygon but within the county: 2 If the polygon approach were in place, when compared with the county approach: –Reduction in total area warned - 73% –Reduction in total number of towns warned - 70%

Polygon Watch and Warning Team Polygon Warning Evaluation WFOs March 1 – September Polygon Evaluation WFOs

Polygon Watch and Warning Team Falsely Alarmed Area Polygon Evaluation test sites, 1 March – 30 September 2005, all warnings: Reduction of area warned, by polygon when compared to the area of the county, or the reduction of “Falsely Alarmed Area” Reduction of area warned, by polygon when compared to the area of the county, or the reduction of “Falsely Alarmed Area”72.07% (Is this the same as a similar reduction in false alarms? Yes, it means a person in a given location, on average, would be falsely alarmed 72% less. Note: This should not be confused with FAR as used in GPRA metrics )

Polygon Watch and Warning Team Value of reduced area warned Dr. Daniel S. Sutter*, Associate Professor of Economics, University of Oklahoma estimates that… If the typical polygon tornado warning was about 1/4 the size of the typical warned county, the value of reduced time under tornado warnings would be almost $100 million per year; % Reducing the area of the typical tornado warning to 1/4 of the current county size would produce about the same increase in value of the warning as reducing the false alarm rate to zero. Reducing the area of the typical tornado warning to 1/4 of the current county size increases warning credibility and, thereby, the value of the warning. % *Author of “eco-weather” articles in Weather and Forecasting 2002 and 2005: ( ).

Polygon Watch and Warning Team Today - Partner Acceptance Media New Industry (StormCall & Emergency Communications Network) Emergency Managers (selective siren activation) FAA (terminal warnings) Private Sector Opportunities (StormHawk)

Polygon Watch and Warning Team Today – Partner Acceptance

Polygon Watch and Warning Team Douglas County, CO. Flash Flood Warning

Polygon Watch and Warning Team Implementation – When? Test Sites – continue as in 2005 “Unofficial” Sites – Participation this season and/or 2007 is encouraged National Implementation – 2008

Polygon Watch and Warning Team Where were we in 2003? All Polygon Warnings Issued in 2003 (SVR, blue and TOR, red)