Situation Specific Call-To-Action Statements

Timothy W. Troutman and Richard Smith
Climate, Water and Weather Division, SRH
Fort Worth, Texas

Mark A. Rose
WFO Nashville
Old Hickory, Tennessee

1. Introduction

The National Weather Service is mandated the responsibility of issuing warnings for the protection of life and property. This is our most important job and requires effective communication of hazardous weather information to the media, emergency managers and the general public. What we say and how we say it are critical in conveying our expectations and communicating the necessary protective actions to be taken.

For many years it has been standard National Weather Service policy to include in warnings a "call-to-action" statement which is intended to do just what the term says. The NWS Southern Region Headquarters initiated the emphasis on call-to-action as part of the warning process in the early 1970s when Dr. B.F. McLuckie from Delaware University was asked to study how to improve the effectiveness of written warnings. McLuckie (1974) developed a workbook and self-study course titled "Warning-A Call to Action" which became an important tool for use by forecasters to improve the effectiveness of their warnings.

Increased demand and the ability to place more detailed information in severe weather warnings have led to the need to more specifically tailor call-to-action (CTA) statements to the specific situation. This paper will attempt to improve upon previous publications addressing this topic. The goal of the warning meteorologist is to convey specific information as concisely as possible. Individual weather offices are therefore encouraged to develop a set of CTA statements which are specific to their local regimes.

The importance of the CTA statement is often overlooked, but it serves a very important purpose in the warning message. It is the part of the warning message which prompts the public to respond, in effect saying, -we have told you where the storm is and where it is going, now here is what you need to think about as it approaches. The CTA statement should prompt listeners to put their severe weather plans into action.

Too often in the past CTA statements have been used simply to provide generic safety rules. In the age of automated crawls on television, CRS and EAS, warning messages have by necessity become shorter, while, at the same time the amount of information forecasters are able to convey to the customers has increased. Text within a warning which may have been devoted to rehashing a list of safety rules can better be used to provide specific, detailed information related to the threat at hand. Basic tornado and severe thunderstorm safety rules are vitally important, but are better suited for public information statements issued before the warnings begin.

Several papers have been published recently on tailored National Weather Service warning CTAs (Smith 1999, Sharp et al. 2000, Smith 2000). With increased demand to place more detailed information in warnings, generic (or "canned") CTAs have proven less effective. With the advent of the Automated Weather Interactive Processing System (AWIPS) and the use of interactive Warning Generation (WarnGen) software to produce warnings, the insertion of CTAs specific to the current meteorological environment has become feasible and can be done very quickly by the warning meteorologist.

This paper will attempt to augment the useful information cited above by categorizing environment-specific CTAs for tornado, severe thunderstorm, and flood/flash flood warnings. The determination of the environment for severe thunderstorm warning CTAs lies largely in mesoscale features such as the wind profile and the WSR-88D reflectivity imagery. For flood/flash flood-producing environments, the meteorologist must understand the atmospheric mechanisms that are creating heavy precipitation, as described by Troutman and Rose (1999).

2. Choosing the Most Effective CTA

Choosing the most effective CTA statement requires knowledge of what is expected to be the main threat with the storm. Given the spectrum of possibilities that may arise when dealing with severe convective storms, it is impossible to foresee every possible scenario.

Call-to-action statements should provide specific, localized information on what actions to take in response to what is to be expected in the warned area. For example, if a storm is about to cross an interstate highway, CTAs might focus on quick actions to be taken by motorists in the path. If a tornado is developing over hilly or mountainous terrain, the CTA could be used to remind people that they will likely not see the tornado coming, so they shouldn't wait for its appearance. The same concept applies when highlighting the storm's main hazards. If you're dealing with the bow echo, you would want to focus on the damaging wind potential. A potential tornadic supercell might warrant a CTA that highlights not only the tornado threat, but also the attendant hail and wind hazards. In order for the CTA to be most effective, only one (or perhaps two) CTAs should be used in each warning or statement - using more leads to a longer warning message and defeats the purpose of the concise format of the bullet warning.

Thunderstorms cover a wide spectrum and present a wide variety of hazards. The same thunderstorm warning may be used to inform the public about a marginal storm producing dime-sized hail and 58 mph winds, but a product with the same name must also make people respond when a violent storm with baseball size hail and 80 mph winds is bearing down on a location. One of the ways to differentiate between the different levels of threat associated with severe storms is by using the call to action portion of the warning. Including specific information about what is anticipated with the storm can be extremely effective.

While all severe thunderstorms are by definition dangerous in that they produce lightning, gusty winds and likely heavy rains, individual storms might not warrant over-emphasis by calling the storm "dangerous." The level of dangerous is relative, in other words. If every warning says "This is a dangerous storm...," there will be no way to highlight the more dangerous events when they occur. Offices might consider developing "emergency" CTA statements to be used only in dire circumstances when the warning or statement deserves extra special attention.

3. Environment Specific CTAs

The following sections contain CTAs which are environment-specific, but the lists are by no means exhaustive. They are intended only to provide examples. Individual offices are encouraged to develop CTAs which are specific to their local regimes (meteorological, geographical, topographical, etc.). Remember, the goals of the warning meteorologist are to convey as much useful information as possible, and be as specific as possible, while also being as brief as possible. The call-to-action statement must also reflect the degree of danger posed by the particular event. Users should know what the danger (threat) is and what to do.

4. Tornado Warning Call-To-Action Statements

a. Tornado indicated by radar:

b. Tornado is difficult to see:

c. Confirmed tornado:

d. Waterspout:

e. Multiple threats:

f. For Motorists:

g. Blowing dust:

5. Severe Thunderstorm Warning Call-To-Action Statements for Supercell Environments

a. For a severe thunderstorm warning with a tornado watch in effect:

b. For a hail storm:

6. Severe Thunderstorm Warning CTAs for Bow Echoes or Squall Line Damage

7. Severe Thunderstorm Warning Call-To-Action Statements for Weak Shear Environments

a. Downburst:

b. For a dry microburst:

c. For excessive lightning:

8. Flood/Flash Flood Warning Call-To-Action Statements

a. For synoptic events- Heavy rainfall produced by synoptic weather system with a strong 500 millibar jet stream (50 knots or greater), primarily from the southwest (Troutman and Rose, 1999). An El Niño winter pattern would be conducive to this situation.

b. For frontal events- Heavy rainfall produced by a quasi-stationary front moving south or southeast (Troutman and Rose, 1999). Another example is a "backdoor" frontal boundary moving slowly southward along the east coast.

c. For mesoscale events- Heavy rainfall occurring primarily during the warm season. Heavy rainfall is produced by the slow movement and training of thunderstorms (Troutman and Rose, 1999).

d. For tropical events- Heavy rainfall typically influenced by a tropical system (Troutman and Rose, 1999).

9. Discussion

The preceding lists of call-to-action statements are not exhaustive. Some offices will not require each example provided here; some will have use of categories that have not been mentioned. The goal of this paper is to simply outline a methodology to allow each office to tailor its own database of CTAs. Therefore, the warning meteorologist can quickly choose the call-to-action which best represents the severe weather potential.

For a storm expected to produce marginally severe weather, the statement "Take cover now! Hail the size of dimes and wind gusts up to 60 mph can be expected" would be much better suited than, say "This is a very dangerous storm. Take cover now. Violent straight line winds and large hail can be expected." The second example exhibits a more generic and less specific use of a call-to-action in relation to the level of threat being faced. The constant abuse of such statements, where the warning far outweighs the threat, may very well decrease the effectiveness of the warning content.

Conversely, a spotter report indicating a large tornado might warrant the more urgent statement "A tornado has been confirmed! Take cover in a sturdy building now. Mobile homes and vehicles are not safe," which is much more effective than "Radar shows strong signs that a tornado is developing. Take cover now!" The difference in the two statements is obvious. The call-to-action must reflect the specific threat and urgency of the situation.

If all National Weather Service offices adopt a situation specific philosophy regarding warning composition, the benefits would far outweigh those from using generic statements, when inserting the call-to-action was almost an afterthought. Situation specific CTAs could mean the difference between an overused statement that is ignored by the media and public and a tailored and specific call-to-action which catches the attention of the listener.

10. Conclusions

With the improved technology enjoyed by National Weather Service meteorologists using the AWIPS system, we now have the ability to apply technological advances to the products we issue, from warnings to forecasts. The warning meteorologist is now able to view radar imagery and other data and compose warnings using the same workstation. This allows the meteorologist to make the decision to warn, plot the warning, and generate the warning text in less than two minutes. Recent automation has allowed the inclusion of specific location and pathcast warning information, which has greatly improved the value of the severe weather warnings we issue (Fig. 1). It only follows that our CTA statements reflect the same detail and precision as the remainder of the warning. Meteorologists are strongly encouraged to transfer their increased abilities to such applications. Situation specific call-to-action statements, when used appropriately and carefully, may prove invaluable to the public and can be included in a warning message in just a few seconds. It is well worth the effort.

11. Acknowledgments

The authors thank Dan Smith, SRH Scientific Services Division Chief and Judson Ladd, Meteorological Services Branch Chief for their reviews. Special thanks go to all the WFOs who provided excellent call-to-action statements for this project. Thanks also go to Michael Murphy, service hydrologist, WFO Nashville, Tennessee, for his assistance in the development of the flood/flash flood warning call-to-action statements.


McLuckie, B.F., 1974: Warning-A Call to Action: Warning and Disaster Response- A Sociological Background. NWS Southern Region Headquarters, 85 pp.

Sharp, D., P. Blottman, and T. Troutman, 2000: Tornado warning situations for east central Florida. Preprints, 20th Conference on Severe Local Storms, Amer. Meteor. Soc., Orlando, FL.

Smith, R., 2000: Communicating the threat in warnings and statements: Call to action statements. Technical Attachment SR/SSD 2000-12, NWS Southern Region Headquarters.

Smith, R. and S. Piltz, 1999: Situation specific tornado warnings at the National Weather Service Forecast Office, Tulsa, Oklahoma. Natl. Wea. Dig., 23, 41-44.

Troutman, T. and M. Rose, 1999: A precipitation climatology for the hydrologic service area of NWSO Nashville, Tennessee. NOAA Tech. Memo. NWS SR-202.

Figure 1. AWIPS WarnGen template showing how Call-To-Action statements can be organized for quick selection during the warning composition process.