NWS to Officially Implement Storm Based Warnings Oct 1st

September 19, 2007 -- Realizing the continuing need to improve the specificity and accuracy of warnings for tornadoes, severe thunderstorms, floods and marine hazards, the NWS will implement Storm-Based Warnings (SBW) on October 1, 2007.

Storm Based Warnings will show the specific meteorological or hydrological threat area and are not restricted to geopolitical boundaries. By focusing on the true threat area, warning polygons will improve NWS warning accuracy and quality. Storm Based Warnings will promote improved graphical warning displays, and in partnership with the private sector, support a wider warning distribution through cell phone alerts, pagers, and web-enabled Personal Data Assistants (PDAs). The media will be able to display the polygons showing the public at large where the area of maximum threat is, and better depict who or what is at greatest risk.

Instead of issuing warnings by county, the local NOAA NWS Weather Forecast Office will be able to narrow its focus on a portion of a county (or counties) that have the greatest threat for being impacted by severe weather. The warned area is defined by latitude and longitude coordinates and depicted by polygons. Utilizing Doppler radar algorithms, the calculated movement of severe storms can be indicated through this technique as well. All of this information will be appended to the bottom of NOAA NWS Storm Based Warnings. SBW polygons will be available for download in GIS format.

Distribution of NOAA Weather Radio or EAS alerts will not initially be impacted, although the warning messages are expected to contain more specific geographic information. According to the SBW FAQ Page, "There will be no change in the NOAA Weather Radio coding and dissemination of warnings with the implementation of storm-based warnings. Long-term there may be limited use of the partial county codes, but that is at least a year away."