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Polygon Warnings The Sharp Focus on Service. NWS Partners’ Workshop Silver Spring, MD June, 2006. Goal – Improving Warning Service. Polygon Eliminates False Alarm for this Area. Review - WFO Case Study. During two convective seasons, one CR WFO issued 46 tornado warnings covering:
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Polygon Warnings The Sharp Focus on Service NWS Partners’ Workshop Silver Spring, MD June, 2006
Goal – Improving Warning Service Polygon Eliminates False Alarm for this Area
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 - 426...a reduction of 72%!
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 Evaluation WFOs Polygon Warning Evaluation WFOs March 1 – September 30 2005
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” 72.07% (Is this the same as a similar reduction in false alarms? Yes, it meansa 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 )
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. %http://www.crh.noaa.gov/sharedoc/crh/taking%20cover.doc http://www.crh.noaa.gov/sharedoc/crh/polygon%20tornado%20warnings.doc *Author of “eco-weather” articles in Weather and Forecasting 2002 and 2005: (http://ams.allenpress.com/pdfserv/10.1175%2FWAF857.1 http://ams.allenpress.com/pdfserv/10.1175%2F1520-0434(2002)017%3C0619:TSETSB%3E2.0.CO%3B2 ).
Today - Partner Acceptance • Media • New Industry (StormCall & Emergency Communications Network) • Emergency Managers (selective siren activation) • FAA (terminal warnings) • Private Sector Opportunities (StormHawk)
Implementation – When? • Test Sites – continue as in 2005 • “Unofficial” Sites – Participation this season and/or 2007 is encouraged • National Implementation – 2008
Where were we in 2003? All Polygon Warnings Issued in 2003 (SVR, blue and TOR, red)
