CARDINAL NEWS has discovered that the Outdoor Warning Siren activation criteria revealed by the 9-1-1 dispatch organization (Northwest Central Dispatch System), which is responsible for activating Outdoor Warning Sirens, does not match the public information guidelines set forth by an online document published on the Village of Arlington Heights official website.
According to a Facebook post with comments from the executive director of Northwest Central Dispatch System (NWCDS), the outdoor warning sirens are not only activated for a Tornado Warning, but are also activated for reported winds of 70 MPH or higher.
According to the Village of Arlington Heights “Weather Preparedness” page “the outdoor warning siren system will be activated and an alert will be sounded if a tornado is determined to be in the area – – this will be a distinctive, three to five minute continuous tone.” There’s no mention of a 70+ MPH winds as a criteria for Outdoor Warning Siren activation.
“Some people believe that the sirens only get activated for a tornado warning, however, they also get activated for reported winds of 70mph or higher.”
— Northwest Central Dispatch System (NWCDS) Executive Director John Ferraro, posting on the official Facebook page for NWCDS
When Outdoor Warning Sirens activated during threatening weather on Friday night, March 31, 2023, there was significant confusion because …
1) outdoor warning sirens were activated while there was no National Weather Service Tornado Warning activated for Arlington Heights, and
2) the Outdoor Warning Sirens were activated five times.
There is a valid reason some people believed on that stormy night that the sirens only get activated for a tornado warning, and why they became confused when there was no Tornado Warning issued for Arlington Heights, and there were five warning siren activations.
The Outdoor Warning Siren definition is improperly explained by the Village of Arlington Heights Weather Preparedness page on the village website.
SIREN ARL HTS …
“(T)he outdoor warning siren system will be activated and an alert will be sounded if a tornado is determined to be in the area – – this will be a distinctive, three to five minute continuous tone.”
In the online document from the Village of Arlington Heights (retrieved March 31, 2023 through April 15, 2023), there is no mention of the 70+ MPH reported wind as siren activation criteria, and there is no mention of an outdoor warning siren protocol for repeat activation. However, there is mention that there is no “all-clear signal due to the fact that secondary funnel systems or a microburst may follow turbulent weather.”
Compare the official Arlington Heights online document referring to Outdoor Warning Siren activation to the official online document from the Village of Palatine. The Outdoor Warning Siren document on the official website for the Village of Palatine (also in the NWDS 9-1-1 dispatch service area) clearly defines the criteria and protocol for Outdoor Warning Siren activation …
SIREN PALATINE …
The siren will cycle for 5 minutes every 10 minutes until the warning is over.
Sirens can be activated due to The National Weather Service criteria for 75+ MPH winds and 1.75 inch+ hail as part of a severe thunderstorm warning or the issuance of a tornado warning.
[NOTE FROM CARDINAL NEWS: It is possible the siren only activates for three minutes — not necessarily five minutes, as it states in the Palatine document. The siren duration may depend on specific communities.]
In an initial Facebook message regarding the March 31 storm on the NWCDS official Facebook page, the NWCDS authorities posted a siren explanation on Friday, March 31, 2023 at 8:26 PM — 34 minutes after the first of five siren activations began at 7:52 PM:
“Sirens were activated in our service area based on potential 90 mph winds with hail.”
— NWCDS 8:26 PM
The NWCDS Facebook post was apparently posted because the 9-1-1 center was inundated with phone call inquiries to the 9-1-1 center regarding the activation of outdoor sirens without a concurrent active Tornado Warning for Arlington Heights. In a comment referring to the official post at 8:26 p.m. from the 9-1-1 center, NWCDS Executive Director John Ferraro stated, “the 911 center is very busy during storms. We posted to answer some of the inquiries.”
There were no responsive Outdoor Warning Siren explanations provided from any of the official social media pages for the Village of Arlington Heights.
Notice also there is a contradiction in defining the criteria for activating the Outdoor Warning Siren for high winds in a Severe Thunderstorm from NWCDS. The official statement from NWCDS stated, “”Sirens were activated in our service area based on potential 90 mph winds with hail.” However, NWCDS Executive Director John Ferraro stated in a comment, “Some people believe that the sirens only get activated for a tornado warning, however, they also get activated for reported winds of 70mph or higher.” Were the potential 90 MPH winds indicated by doppler radar, or were the potential 90 MPH winds merely indicated as a potential in a short-term forecast? Compare this to a Tornado Watch, when the potential for a tornado exists, but there is no Outdoor Warning Siren activation because there are no tornado reports by spotters, or there are no tornados indicated by doppler radar. Outdoor Warning Sirens don’t activate for a Tornado Watch, so we should be assured that Outdoor Warning Sirens aren’t activated unless 70+ MPH winds are observed or indicated in real-time. There are actually three main inputs in making National Weather Service warning decisions for 70+ MPH winds in severe thunderstorms, and it is difficult to get adequate warning lead time while maintaining a low false alarm rate, according to the National Weather Service Office in Des Moines, Iowa.
These conditions involve …
1.) fast movement of thunderstorms,
2.) a significant damage swath that is small compared to the thunderstorm system, and that
3.) a good percentage of these severe events start out at 70+ mph, according to NWS Des Moines.
Keep in mind that the speed of a storm cell traveling across counties is not the same as the wind speed produced by the storm cell. A storm cell could be moving across a county at 54 MPH, but the wind speed in the storm cell could be higher. Also realize a storm cell that is traveling almost 60 miles per hour will travel almost five miles in five minutes.
How is the Decision Made to Include Winds of 70 mph or Greater in a Severe Thunderstorm Warning? (There are 3 Main Inputs)
“National Weather Service meteorologists make warning decisions based upon three main inputs, but in reality, there are a myriad of factors. Input number one is Doppler radar data (emphasis added) alongside other observations like satellite, lightning activity and surface observations. Number two is the temperature, moisture and wind shear environment through which the storms are moving — this helps the meteorologist narrow down which outcomes are the most likely. Third, but certainly not least are spotter reports (emphasis added). These help the meteorologist know if the severe radar “signature” is actually producing damage, if the storm is intensifying or weakening. Spotter reports also help to calibrate how severe an event is or might become compared to other observations and radar. The decision to include 70 or 80 mph wind tags is not made lightly, knowing that such events are uncommon to rare. Intensity of all factors, including radar data and reports, are weighed and reweighed against classic shapes and conceptual models of wind storms, elevations of features, interaction with neighboring storm cells, speed of movement and acceleration. Sometimes the speeds, shapes and radar intensities evolve in a classic fashion matching previous storms or idealized models of high wind producers. Sometimes long swaths of severe damage are produced, like the derechos of 11 July 2011 and 29 June 1998 in Iowa, and the 29 June 2012 in the eastern U.S. In those events, advance lead time can be provided in NWS Severe Thunderstorm Warnings or Severe Weather Statements. In other events, the high winds develop much more suddenly or unconventionally. In such cases warning lead time may be short, or the warning could be based upon spotter reports. As a result, it is essential that spotter information is relayed quickly to the NWS in order to warn people downstream.”
An apparent tornado was captured on a security video (Facebook post) at an Addison Fire Protection District fire station at 8:15 p.m., according to Addison Fire Protection District. At the very beginning of the video, a tornado moves from left to right in the upper-left corner of the video. The video was posted on the official Facebook page for Addison Fire Protection District on April 1, 2023 fat 8:47 a.m. Several people expressed concern that they didn’t here a “warning siren” in Addison. There was no Tornado Warning for Addison issued on March 31, 2023. Although there were about 70 Tornado Warnings in Illinois counted from around 6:00 p.m. and later on Friday, March 31, 2023, the closest Tornado Warning to Addison was near south suburban Chicago Heights and Park Forest, and was activated about 8:35 p.m. and the warning was valid until about 8:45 p.m.
The new criteria for Outdoor Warning Siren activations have been in the works the past 10 to 15 years. The 70+ MPH wind criteria and 1.75″ hail criteria are each relatively new criteria upgraded from Tornado Warning only criteria from older protocols, which still exist in some communities. There is research published (Severe Weather Data for Siren Activation National Weather Service Des Moines Iowa July 2013 [PDF]) that supports decisions to activate Outdoor Warning Sirens for 70+ MPH winds and 1.75″ hail.
Compare 70+ MPH winds to The Enhanced Fujita Scale for tornados …
An EF-0 tornado is rated by a 3 second wind gust damage of 65 to 85 MPH.
An EF-1 tornado is rated by a 3 second wind gust damage of 86 to 110 MPH.
An EF-2 tornado is rated by a 3 second wind gust damage of 111 to 135 MPH.
An EF-3 tornado is rated by a 3 second wind gust damage of 136 to 165 MPH.
An EF-4 tornado is rated by a 3 second wind gust damage of 166 to 200 MPH.
An EF-5 tornado is rated by a 3 second wind gust damage over 200 MPH.
Criteria and protocols for activation of Outdoor Warning Sirens are decided by local authorities. While the National Weather Service provides the weather alerts and the scientific support for activation of Outdoor Warning Sirens, the National Weather Service does not have authority over Outdoor Weather Sirens, and does not activate the sirens. The local authorities have control of criteria and protocols for their Outdoor Warning Sirens.
Local governments and 9-1-1 centers acquire a wealth of information about the status of their communities, and have the raw data and resources to develop a significant and valuable understanding of the risks and risk reduction behavior to enrich lives of citizens in their respective service areas.
The Outdoor Warning Siren contradiction between the Village of Arlington Heights and NWCDS points to important questions …
1) How well do authorities prepare with integrity for proper notification of citizens and their own employees in emergency situations?
2) How well do authorities prioritize and understand the importance and moral duty to provide citizens and employees with information that saves lives and enriches lives by providing the proper measure of risk avoidance notifications?
3) How well do authorities respect the obligation to reduce workload and unnecessary stress on their own employees by having a robust notification system and coherent information system that minimizes unnecessary tasks and workload on front-line public safety personnel?
4) How well do authorities communicate to assure citizens and employees that executives and administrators are working to achieve these goals?
When do Outdoor Warning Sirens activate in a storm?
Outdoor warning sirens, sometimes known as tornado sirens or severe weather sirens, are typically activated in the following severe weather circumstances:
Tornado Warning: Outdoor warning sirens are activated when a tornado warning has been issued by the National Weather Service (NWS) for the specific area where the sirens are located. A tornado warning means that a tornado has been detected by radar or reported by a trained spotter, and is considered imminent or already occurring. Sirens are used to alert people who are outdoors to seek shelter immediately and take appropriate precautions.
Severe Thunderstorm Warning with Damaging Winds: Outdoor warning sirens may also be activated when a severe thunderstorm warning has been issued by the NWS that includes the threat of damaging winds. This typically means that winds of 70 miles per hour or higher are expected, which can cause significant damage to structures and pose a threat to people outdoors.
Severe Thunderstorm Warning with Hail 1.75″ + in Diameter: In some areas, outdoor warning sirens may be activated when severe thunderstorms with hail of a certain size or larger is expected. The National Weather Service does not issue a specific “hail warning” but a Severe Thunderstorm Warning with the inclusion of large hail advises people to seek shelter. Large hail can cause death, injury and damage to property — especially vehicles and crops. In the United States, large hail is more common Kansas, Nebraska, Oklahoma, and Texas.
The National Weather Service does not activate Outdoor Warning Sirens. The specific criteria for activating outdoor warning sirens may vary depending on the location and jurisdiction. The weather safety best plan is to stay informed about the local guidelines and instructions from local authorities, and to have multiple reliable sources of weather information, such as a NOAA weather radio, local news, and weather apps or websites with forecasts, alerts and radar for a smartphone or computer.
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Why Didn’t My Outdoor Warning Siren Activate or Did It Activate Improperly?
Malfunction or Maintenance: Outdoor Warning Sirens are mechanical or electronic devices that require regular maintenance and can malfunction. A siren undergoing maintenance might not function properly at the time the tornado warning occurs. Tornados can also activate inadvertently for a variety of reasons.
Limited Coverage Area: Outdoor Warning Sirens are typically installed in specific areas, such as neighborhoods or municipalities, and may not cover the entire region. If the tornado occurred outside the coverage area of the siren, it may not have been activated, but you may hear it in the distance.
Lack of Tornado Warning: Outdoor Warning Sirens are usually activated based on tornado warnings issued by the local National Weather Service (NWS) office. If there was no tornado warning in place at the time of the tornado, the siren would probably not activate. Certain types of clouds look like a tornado or look similar to tornado-producing clouds to the untrained eye.
Human Error: Outdoor Warning Sirens are often activated by human operators who may make mistakes or face technical difficulties in the activation process. Human error, miscommunication, or technical issues could potentially prevent the siren from being activated, or cause the siren to be activated by mistake. Decades ago there was a dispatcher that looked out a window and saw clouds that made her panic. She activated the “tornado siren” when there was no tornado warning.
System Failure: Outdoor Warning Siren systems can have complex infrastructure involving communication networks, control centers, and activation mechanisms. If there was a failure in any part of the system, such as a power outage, communications failure, or equipment malfunction, an outdoor warning siren could fail to activate.
Keep in mind it is possible that you might hear an Outdoor Warning Siren in the distance that does not apply to your location.