Alerting Best Practices

Criteria for Issuing Warnings

Deciding whether to issue a public warning can be a difficult decision.  Ultimately it will be a matter of local judgment; however, it will be helpful to have an outline of decision criteria to assist you with the process and ensure that a timely decision is made.

When deciding whether to issue a public warning, the following criteria can be applied:

  • Does the hazardous situation require the public to take immediate action?
  • Does the hazardous situation pose a serious threat to life or property?
  • Is there a high degree of probability that the hazardous situation will occur?
  • Are other means of disseminating the information adequate to ensure rapid delivery of urgent information?

Your State emergency plans may provide criteria for issuing public alerts, including activating IPAWS; if so, they should be incorporated into your local procedures.

Characteristics of Effective Alert Messages

You learned about the characteristics of effective alert messages in detail in IS 247.a-IPAWS WBT. We have summarized them below for your reference. Select each signboard to learn more.

  • Type of Threat: What is/are the hazards that are threatening? What are the potential risks for the community?
  • Location: Where will the impacts occur? Is the location described so those without local knowledge can understand their risk?
  • Duration: When will it arrive at various locations? How long will the impacts last?
  • Source of Message: Who is issuing the warning? Is it an official source with public credibility?
  • Magnitude: A description of the expected impact. How bad is it likely to get?
  • Likelihood: The probability of occurrence of the impact.
  • Protective Behavior: What protective actions should people take and when? If evacuation is called for, where should people go and what should they take with them?

  • Specific: If the message is not specific enough about the "Who? What? When? Where? Why? How?," the public will spend more time seeking specific information to confirm the risk. If necessary, be specific about what is or is not known about the hazard.
  • Consistent: An alert/warning should be internally consistent, that is, one part of the message should not contradict another part. It should be consistent with messages that are distributed via other channels. To the extent possible, alerts/warnings should be consistent from event to event, to the degree that the hazard is similar.
  • Certain: Avoid conveying a sense of uncertainty, either in content or in tone. Confine the message to what is known, or if necessary, describe what is unknown in certain terms. Do not guess or speculate.
  • Clear: Use common words that can easily be understood. Do not use technical terminology or jargon. If protective instructions are precautionary, state so clearly. If the probability of occurrence of the hazard event is less than 100%, try to convey in simple terms what the likelihood of occurrence is.
  • Accurate: Do not overstate or understate the facts. Do not omit important information. Convey respect for the intelligence and judgment of your public.

  • Clear and Simple Language: A general guideline to follow is to use clear and simple language whenever possible, with minimal use of abbreviations. The most important information should be presented first.
  • Text-to-Speech Conversion: Care must be taken in composing text that is converted to audio by text-to-speech equipment. Consult your NWS Weather Forecast Office for local guidance regarding NOAA Weather Radio requirements.
  • Consistent Audio: IPAWS and CAP can accommodate pre-recorded audio files that may be used by Emergency Alert System participants (e.g., broadcasters) and that assist the blind or those with low vision. The audio should be as consistent as possible with the text and should ensure that any abbreviations are spoken as full words.
  • Ample Text and Audio to Explain Images/Maps: Since IPAWS OPEN provides the capability to deliver multimedia messages, ample text and audio should be provided to explain images or maps, so that message recipients can understand the meaning of what is being conveyed graphically.
  • Screen Reading and Text-to-Speech Devices: Some mobile devices and currently available software provide screen reading and text-to-speech conversion capabilities for alerts delivered via Internet technologies. When considering these and other translation technologies, craft messages that avoid non-standard language formats and terminology.

CFR 2010 Title 47 Volume 1 Part 11


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