SR SSD 2000-12
5/2000

Technical Attachment

Communicating the Threat in Warnings and Statements:
Call to Action Statements

Richard Smith
National Weather Service Southern Region Headquarters
Meteorological Services Division

1. Introduction

The National Weather Service is charged with the responsibility of issuing warnings for the protection of life and property. This is our most important job and one that requires that we effectively communicate 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 necessary protective actions.

The call to action statement (CTA) is often overlooked, but serves a very important purpose in the warning message. The CTA is the part of the warning message that prompts response - we've told you where the storm is and where it's going, now here's what you need to think about as it heads your way, and to put your severe weather plan into action.

In the past, call to action statements were used to provide basic 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 that forecasters need to convey to the customers has increased. Space taken up rehashing a list of safety rules is space that might be better used providing some specific, detailed information related to the threat at hand. Basic tornado and severe thunderstorm safety rules might be better suited for public information statements issued before the warnings begin.

2. Choosing the proper CTA

Choosing the proper call to action 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. However, given the knowledge of the most common type of storms and the most common threats associated with those storms, local offices can develop a substantial list of CTA's that will cover most every situation in their respective warning areas.

Call to action statements should provide specific, localized information on what is to be expected in the warned area. For example, if a storm is about to cross an interstate highway, CTA's 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 not see the tornado coming. The same concept applies when highlighting the storm's main hazards. If you're dealing with a 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 maybe two) 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 severe thunderstorm warning used to inform about a marginal storm producing dime size hail and 50 mph winds must also make people respond when a violent storm with baseball hail and 80 mph winds is bearing down on them. One of the ways to differentiate between the different levels of 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.

Some call to action statements should be reserved for those situations when storms present a genuine threat to the lives and property of those in the storm's path. While all thunderstorms are dangerous in that they produce lightning, gusty winds and heavy rains, most situations do not warrant defining a storm as "dangerous." If every warning says "This is a dangerous storm . . . ," there will be no way to highlight those truly dangerous events when they occur. Offices might consider developing "emergency" call to action statements to be used ONLY in dire circumstances when the warning or statement deserves extra special attention.

3. Setting up CTA's in WarnGen

One of the nice things about call to action statements is that they, in most cases, can be set up well in advance and are available with one mouse click when composing a warning or statement. WarnGen call to action statements can be customized to meet local office needs quite easily. CTA's can be developed to cover situations common to a local office's warning area, and may be written to encompass a wide variety of cases.

The character string "!** **!" can be used in WarnGen templates to prompt the forecaster for input. For example, in the following CTA, the character string must be replaced before the product is transmitted.

DAMAGING WINDS MAY OCCUR UP TO !** **! MILES AHEAD OF THE RAIN....

4. Examples

The collection below contains examples of call to action statements for use in tornado and severe thunderstorm warnings. Most of these fit the desired format of the CTA: short (two lines or less) and specific (threat, location, event). This is not an exhaustive list - it is designed to provoke thought and give some ideas on how call to action statements might be composed.

Tornado/Waterspout Call to Action Statements

THIS STORM SHOWS STRONG ROTATION AND MAY PRODUCE A TORNADO AT ANY TIME. DO NOT WAIT...GO TO A SAFE PLACE NOW! PUT AS MANY WALLS BETWEEN YOU AND THE OUTSIDE AS POSSIBLE.

A TORNADO MAY FORM AT ANY TIME - TAKE COVER NOW! ABANDON MOBILE HOMES AND VEHICLES FOR MORE SUBSTANTIAL SHELTER. AVOID WINDOWS

RADAR SHOWS STRONG SIGNS THAT A TORNADO IS DEVELOPING - TAKE COVER NOW!

IN ADDITION TO THE THREAT OF A TORNADO...DAMAGING HAIL AND STRONG WINDS CAN BE EXPECTED. GO TO A SAFE PLACE NOW!

LARGE HAIL AND STRONG STRAIGHT LINE WINDS ARE ALSO EXPECTED.

DOPPLER RADAR INDICATED A TORNADO MAY FORM AT ANY TIME. TAKE COVER NOW. ABANDON MOBILE HOMES AND VEHICLES. MOVE TO AN INTERIOR ROOM OR HALLWAY ON THE LOWEST FLOOR.

THIS IS A VERY DANGEROUS STORM. IF YOU ARE NEAR ITS PATH YOU SHOULD BE READY FOR DESTRUCTIVE HAIL...VIOLENT WINDS AND POSSIBLY A TORNADO. MOVE TO A SAFE PLACE NOW!

IN ADDITION TO THE THREAT OF A TORNADO...LARGE HAIL AND DAMAGING WINDS CAN BE EXPECTED. GO TO A SAFE PLACE NOW.

MOTORISTS SHOULD LOOK FOR SHELTER IN A SUBSTANTIAL BUILDING. AS A LAST RESORT...TAKE COVER IN A DITCH OR LOW SPOT. OVERPASSES ARE NOT SAFE!

DO NOT STOP UNDER BRIDGES OR HIGHWAY OVERPASSES. THEY OFFER NO PROTECTION FROM VIOLENT WINDS. BLOCKING THE ROAD WILL PREVENT OTHERS FROM REACHING SAFE SHELTER.

VERY HEAVY RAIN MAY MAKE THIS TORNADO INVISIBLE - TAKE COVER NOW! IF YOU WAIT UNTIL YOU SEE OR HEAR IT COMING IT MAY BE TOO LATE TO GET TO A SAFE PLACE.

THIS TORNADO IS WRAPPED IN RAIN - IF YOU WAIT UNTIL YOU SEE OR HEAR IT COMING IT MAY BE TOO LATE TO GET TO A SAFE PLACE. TAKE COVER NOW!

THIS TORNADO IS LIKELY OBSCURED BY RAIN AND MAY NOT BE VISIBLE. TAKE COVER NOW

TORNADOES AT NIGHT ARE ESPECIALLY DANGEROUS. DO NOT WAIT UNTIL YOU SEE OR HEAR THE TORNADO - IT MAY BE TOO LATE. TAKE COVER NOW!

TORNADOES IN HILLY OR MOUNTAINOUS TERRAIN ARE HARD TO SEE. DO NOT WAIT TO SEE OR HEAR THE TORNADO - GO TO A SAFE PLACE NOW!

IF NO UNDERGROUND SHELTER IS AVAILABLE...GO TO AN INTERIOR ROOM ON THE LOWEST FLOOR. MOBILE HOMES AND VEHICLES ARE NOT SAFE.

DO NOT RUN OUTSIDE TO FIND THE TORNADO - TAKE COVER NOW! IF YOU CANNOT GET UNDERGROUND...GO TO AN INTERIOR ROOM ON THE LOWEST FLOOR. AVOID WINDOWS!

A TORNADO HAS BEEN CONFIRMED! TAKE COVER IN A STURDY BUILDING NOW. MOBILE HOMES AND VEHICLES ARE NOT SAFE.

IF YOU ARE NEAR THE PATH OF THIS TORNADO...TAKE COVER IN AN INTERIOR ROOM ON THE LOWEST FLOOR. PROTECT YOUR HEAD AND BODY FROM FLYING DEBRIS.

THIS IS AN EXTREMELY DANGEROUS AND LIFE THREATENING SITUATION. IF YOU ARE NEAR THE PATH OF THIS LARGE AND DESTRUCTIVE TORNADO..TAKE COVER NOW!

THIS IS A DANGEROUS STORM - TAKE COVER NOW! IF YOU CANNOT GET UNDERGROUND... SEEK SHELTER ON THE LOWEST FLOOR IN AN INTERIOR ROOM. MOBILE HOMES AND VEHICLES ARE NOT SAFE.

A WATERSPOUT IS A TORNADO OVER WATER THAT CAN BE DANGEROUS AND EVEN DEADLY. SMALL CRAFT CAN BE SWAMPED OR OVERTURNED BY A WATERSPOUT. STAY AWAY FROM THEM AT ALL TIMES!

WATERSPOUTS THAT MOVE ONSHORE BECOME TORNADOES. SHORELINE RESIDENTS SHOULD BE ALERT AND SEEK SHELTER IF THREATENING WEATHER APPROACHES.

BLOWING DUST OR DEBRIS AND SUDDEN WIND CHANGES MAY MEAN A TORNADO IS APPROACHING. TAKE COVER INSIDE A STURDY BUILDING AND STAY AWAY FROM WINDOWS.

Severe Thunderstorm Call to Action Statements

A TORNADO WATCH IS ALSO IN EFFECT. TORNADOES CAN DEVELOP SUDDENLY FROM SEVERE THUNDERSTORMS.

RADAR INDICATED SOME ROTATION WITH THIS STORM. PEOPLE NEAR THE PATH SHOULD GO TO A SAFE PLACE NOW!

SEVERE THUNDERSTORM WINDS CAN BE AS DESTRUCTIVE AS A TORNADO. FOR YOUR SAFETY...GO TO A SAFE PLACE IMMEDIATELY.

THIS THUNDERSTORM MAY PRODUCE WEAK...SHORT-LIVED TORNADOES ALONG ITS LEADING EDGE. HOWEVER...THE MAIN THREAT IS DAMAGING WINDS. SEEK SHELTER INSIDE A STURDY BUILDING AND AVOID WINDOWS.

VERY SMALL...BRIEF...BUT DANGEROUS TORNADOES ARE POSSIBLE WITH THIS STORM. STAY INDOORS AWAY FROM WINDOWS UNTIL THE STORM HAS PASSED.

SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES SUDDENLY. BE ALERT FOR RAPIDLY CHANGING WEATHER CONDITIONS AND BE READY TO ACT QUICKLY.

GO INSIDE A STURDY BUILDING AND STAY AWAY FROM WINDOWS! A TORNADO WATCH IS IN EFFECT. SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES.

WIDESPREAD WIND DAMAGE IS EXPECTED WITH THESE STORMS. WINDS MAY KNOCK DOWN TREES AND POWER LINES AND DAMAGE BUILDINGS. TAKE COVER NOW.

HAIL...DAMAGING WINDS AND TORRENTIAL RAIN ARE EXPECTED WITH THIS STORM. TAKE COVER IN A SUBSTANTIAL SHELTER WHILE THE STORM PASSES.

DAMAGING WINDS AND TORRENTIAL RAINS ARE LIKELY. GO INSIDE A STURDY BUILDING AND STAY AWAY FROM WINDOWS.

DESTRUCTIVE HAIL CAN BE EXPECTED WITH THIS STORM - TAKE COVER NOW. GO TO THE LOWEST FLOOR OF A STURDY BUILDING AND AVOID WINDOWS!

DESTRUCTIVE WINDS CAN BE EXPECTED. IF YOU CANNOT GET UNDERGROUND... GO TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A STURDY BUILDING. AVOID WINDOWS!

DESTRUCTIVE WINDS CAN BE EXPECTED - TAKE COVER NOW! VEHICLES AND MOBILE HOMES ARE NOT SAFE.

LARGE HAIL BLOWN BY VIOLENT WINDS WILL CAUSE EXTENSIVE DAMAGE - TAKE COVER NOW! FIND SUBSTANTIAL SHELTER. AVOID WINDOWS...VEHICLES AND MOBILE HOMES!

HAIL TO THE SIZE OF !** **! AND WIND GUSTS TO !** **! MPH CAN BE EXPECTED.

THIS IS A VERY DANGEROUS STORM - TAKE COVER NOW! VIOLENT STRAIGHT LINE WINDS AND LARGE HAIL CAN BE EXPECTED.

THESE STORMS WILL PRODUCE EXTENSIVE PROPERTY DAMAGE - TAKE COVER NOW! IF YOU CANNOT GET UNDERGROUND GO TO AN INTERIOR ROOM ON THE LOWEST FLOOR. VEHICLES AND MOBILE HOMES ARE NOT SAFE.

MOTORISTS ON !** **! WILL ENCOUNTER DAMAGING HAIL...STRONG WINDS AND BLINDING RAIN. FIND SUBSTANTIAL SHELTER NOW. BRIDGES AND OVERPASSES ARE NOT SAFE!

DAMAGING WINDS CAN BE EXPECTED. GO TO A SAFE PLACE NOW AND REMAIN PROTECTED UNTIL THE STORM HAS PASSED

IN ADDITION TO DAMAGING WINDS...LARGE HAIL CAN ALSO BE EXPECTED.

IN ADDITION TO DESTRUCTIVE HAIL...DAMAGING WINDS CAN ALSO BE EXPECTED.

DAMAGING WINDS MAY OCCUR UP TO !** **! MILES AHEAD OF THE RAIN. GO TO A SAFE PLACE UNTIL THE STORMS HAVE PASSED.

STAY AWAY FROM WINDOWS.

DAMAGING WINDS...HEAVY RAIN AND HAIL ARE LIKELY. SEEK SHELTER IN A STURDY BUILDING AND STAY AWAY FROM WINDOWS.

HIGH WINDS AND LARGE HAIL CAN SPREAD QUICKLY ACROSS OPEN RANGELAND. MOVE TO PROTECTED AREAS WHEN BLOWING DUST...SUDDEN WIND CHANGES OR LIGHTNING APPROACH.

HAIL UP TO THE SIZE OF !** **! AND WIND GUSTS TO AT LEAST !** **! MPH ARE LIKELY.

THESE STORMS WILL LIKELY PRODUCE PARTICULARLY DAMAGING WINDS. MOBILE HOMES AND VEHICLES ARE ESPECIALLY SUSCEPTIBLE TO HIGH WINDS AND MAY BE OVERTURNED.

THIS THUNDERSTORM IS CAPABLE OF PRODUCING EXTREMELY LARGE HAIL WHICH MAY CAUSE INJURY AND DAMAGE PROPERTY. TAKE SHELTER IN A STURDY BUILDING. AVOID WINDOWS.

DOPPLER RADAR INDICATED THIS STORM MAY CONTAIN DESTRUCTIVE HAIL TO THE SIZE OF BASEBALLS OR LARGER.

STRONG AND DAMAGING WINDS ARE LIKELY WITH THIS STORM...BUT THERE WILL BE LITTLE RAIN. TAKE COVER IN A STURDY BUILDING UNTIL THE STORM PASSES.

VERY LARGE HAIL AND DAMAGING WINDS ARE EXPECTED WITH THIS DANGEROUS STORM. A TORNADO COULD ALSO FORM WITH LITTLE WARNING. SEEK SHELTER NOW!

THIS STORM WILL PRODUCE DAMAGING HAIL...CAPABLE OF CAUSING EXTENSIVE PROPERTY DAMAGE AND SERIOUS INJURY. TAKE COVER NOW! AVOID WINDOWS.

THESE STORMS WILL PRODUCE HURRICANE FORCE WINDS AND WILL LIKELY CAUSE WIDESPREAD DAMAGE. IF YOU CANNOT GET UNDERGROUND...GO TO AN INTERIOR ROOM ON THE LOWEST FLOOR. AVOID WINDOWS.