Impact Based Warnings
- Experimental Product -

Home Warning Example 2012 Examples Descriptive Handout Contact Us

What Is This Experiment About?




An experimental National Weather Service warning enhancement will be used across much of the central U.S. this thunderstorm season (beginning April 1).  This is an expansion of a smaller NWS experiment that began in Kansas and Missouri in 2012. 

The Impact Based Warning (IBW) experimental product is an effort to better communicate severe weather threats within National Weather Service warnings.  While the basic function of Severe Thunderstorm and Tornado warnings will remain the same, additional enhanced information will be provided within the warning to provide additional expected "impact" information.

The goals are to provide more information through the warnings in order to facilitate improved public response and decision making, and to better meet societal needs in the most life-threatening weather events.  This effort is in response to key findings from recent service assessments of devastating tornadoes in 2011, particularly the EF-5 tornado in Joplin, MO. 

Please refer to the video below, as well as the information provided throughout this web page for additional information regarding the IBW experiment that begins April 1, 2013

To provide input on the IBW demonstration, please visit

Informational Video

Presentation Slides Presentation Script

Locations Using Impact Based Warnings


  • Provide additional valuable information to media and Emergency Management officials
  • Facilitate improved public response and decision making
  • Better meet societal needs in the most life-threatening weather events

  Intended Outcomes

  • Optimize the convective warning system within the existing structure
  • Motivate proper response to warnings by distinguishing situational urgency
  • Realign the warning message in terms of societal impacts
  • Communicate recommended actions & precautions more precisely
  • Evaluate ability to distinguish between low impact and high impact events

  Enhancing Warnings Through

  • Improve communication of critical information
  • Make it easier to quickly identify the most valuable information
  • Enable prioritization of key warnings in your area of interest
  • Indicate different levels of risk within the same product
  • Enable the National Weather Service to express a confidence level of potential impacts


 is the U.S. government's official web portal to all federal, state and local government web resources and services.