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Polygon Warnings

Polygon Warnings . Mike Coyne National Weather Service Southern Region. Overview. Background Information The advantages of polygon warnings What are the issues concerning the polygon? What is currently being done Future Plans. Background.

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Polygon Warnings

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  1. Polygon Warnings Mike Coyne National Weather Service Southern Region

  2. Overview • Background Information • The advantages of polygon warnings • What are the issues concerning the polygon? • What is currently being done • Future Plans

  3. Background • National Weather Service issues four types of short-fused warnings: • Tornado Warnings (TOR) • Severe Thunderstorm Warnings (SVR) • Flash Flood Warnings (FFW) • Special Marine Warnings (SMW) • Issued normally for one county at a time • Can lead to a large false-alarm area, especially in the case of large or irregular-sized counties

  4. Background • Verification has been strictly county-based • Legacy dissemination methods all tied to counties: • NOAA All-Hazards/Weather Radio • Uses SAME alert code based on counties • Internet displays – again, based on counties

  5. What is the Polygon?

  6. What is the Polygon? • Allows forecaster to graphically highlight the area of greatest threat • Creates a template text product for the warning, including proper headers, issue/expiration times, county UGC codes • ALSO: includes latitude/longitude vertex points for the pathcast, or polygon warning --- LITTLE USED by NWS, partners, and public

  7. What is the Polygon?

  8. Polygon Advantages • Shows specifically where the threat is located • More accurately shows warning area on systems displaying warnings graphically • Reduction of risk area to public • Better graphical description capabilities • Wider local distribution via cell phones, PDAs, etc. • Increase NWS role in the confirmation part of the warning process • Private sector starting to turn to polygons • Allows NWS to refine warnings to true threat area • Allows us to track and set goals for false alarm area • Better warning quality • Keeps NWS in technological step

  9. Polygon Advantages Polygon Eliminates Area False Alarmed

  10. One WFOs Study (2004) • In 2004, issued tornado warnings that covered: • 31,990 square miles (494 individual towns) • Utilizing the polygon approach, the polygons covered: • 9,500 square miles (152 individual towns) • If the polygon approach were in place: • Would have reduced our total warning area by 22,490 square miles • Would have unnecessarily warned 242 fewer towns • That's a reduction of 70%!

  11. Better Warning Information

  12. Better Warning Information

  13. Better Warning Information

  14. Polygon Issues • How should NWS treat these warnings? • Is the polygon the area of maximum threat? • Is the polygon the warning area? • What does our customers/partners wish to see? • What are the internal and external education issues with polygon warnings? • Do we need to reexamine the entire warning process?

  15. Other Issues • Training: • Software (e.g. Warngen, WWA, Storm Data) • How to train at the operation interface (scientific, technical, cultural) • Dissemination: • Education/public outreach • Interoperability of dissemination systems • How to handle cross-CWA boundary issues (polygons crossing from one CWA to another)? • Customer concerns over potential increase in number of warnings (broadcast interruptions, etc.) • Verification: • How to measure skill w/respect to polygon warnings? • Consider and understand potential impact on GPRA goals • Operations: • Workload (keeping track of multiple polygons; multiple small polygons, or few large polygons? – situation dependent?) • Do we restrict to short-fuse warnings or extend to long-fused warnings

  16. No Issue is Trivial 2 maps of all Polygon Warnings Issued in 2003 Can you see the counties?

  17. Polygon Team • NWS Polygon Team formed in 2004 • Purpose: Define issues associated with the polygon approach to the warning process and recommend solutions. • Test will be run in 2005 with some NWS forecast offices • De-emphasis on county borders • Focus on location of severe threat • Test alternate measures of verification that are polygon-based • Will open the door for dissemination using current technologies (e.g., cell phones, pagers, GPS-enabled devices)

  18. Team Members • Mike Looney, CRH (facilitator) • Mike Coyne, SRH • Steve Naglic, WCM WFO Columbia SC (ER) • Pete Wolf, SOO WFO Jacksonville, FL • Jeff Lorens, WRH • Ken Waters, PRH • Brent MacAloney (OCWWS) • Rich Okulski (OCWWS) • Noreen Schwein, CRH (Hydrology) • Joe Schaefer, SPC

  19. Questions Mike.Coyne@noaa.gov (817) 978-1100 x. 153

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