Recap of Oct. 2 severe weather, challenges faced, and a word on siren policy

Until last night, it had been a long time since widespread severe weather (not including biblical flooding events) had affected the Memphis metro. Tornado Warnings were last issued in late April. A well-advertised, and well-forecast, squall line moved through the region during the late evening hours bringing many reports of wind damage and several areas of rotation on radar. No reports of tornado touchdowns were received in the immediate area, though possible tornado damage occurred in northeast AR.

Every county in the metro was under a Tornado Watch and Severe Thunderstorm Warning as the line moved through and several areas were also under Tornado Warnings due to radar-indicated rotation in the fast-moving line. An early recap of the night from NWS-Memphis can be found here. They also discuss areas they intend to survey for storm damage.

Severe weather reports received by NWS as of mid-morning Friday. Most were wind or wind damage, though a possible tornado struck east of Jonesboro.

There are two main issues I want to address in this blog: 1) technology challenges and 2) outdoor warning siren policy.

Technology challenges

Technology. We love it for many good reasons. It allows us to do many things quickly and more efficiently than ever before. It allows us to push specific warning information to you via your smartphone almost as soon as it is issued by the NWS. But it also has its pitfalls. Namely when it doesn't work. Fortunately our critical warnings worked flawlessly last night, but there were other issues.

MWN StormView Radar on the website and mobile apps was one such problem. Due to multiple malicious attacks on multiple weather vendors' servers yesterday, including at least one big name and ours (though not targeting MWN directly), our radar stopped updating. The timing was awful. We apologize for and sincerely regret this major inconvenience; unfortunately some idiots like to "be funny" at other's expense. We're not laughing. If they can be tracked down, they ought to be prosecuted. We will be following up with our vendor on best practices going forward, but the outage was (and remains) completely outside of our control, though we take responsibility for providing the service to you.

In addition to radar issues, MWN headquarters lost internet connectivity as the squall line was moving across the river and Tornado Warnings were being issued (it also remains down this morning). This outage hampered our ability to disseminate information (including critical social media posts and data from our Bartlett weather station), monitor incoming data (including radar), troubleshoot the ongoing issues with our web radar, and communicate with the NWS. I'm not turning this into a bash-fest on our internet provider. This is the first outage we have had in months, perhaps over a year, and the connection handles everything we throw at it on a routine basis. The point is, once again, technology is not flawless and is subject to outage.

I want to take just a minute though to recognize MWN interns Kevin Terry and William Churchill for exemplary service last night as MWN's internet feed went down. Working from Mississippi State (there are advantages to working from disparate locations during severe weather events!), Kevin and William immediately took over nowcasting responsibilities in the middle of the event and didn't miss a beat. I'm guessing that most people watching our Facebook or Twitter feeds last night didn't know a major link in the chain had failed. That is a sign of a well-oiled machine and I thank them for their awesome work and dedication to all of you! My wife loaned her laptop to the cause (thanks honey!) and, courtesy of a smartphone hotspot, I was able to re-engage on a limited basis. Sometimes it takes a team effort and I've got one of the best in #TeamMWN!

Tornado Warnings and outdoor siren policy

The other discussion that needs to be had is regarding outdoor warning siren policies. Truth be told, it's been a relatively quiet couple of years for severe weather in the metro. Sometimes that "lack of practice" results in lack of preparation and awareness. The main issue we saw last night was in Shelby County, but the general principles apply most anywhere. Recall that Tornado and Severe Thunderstorm Warnings are not issued by county. They are "storm-based polygons," meaning they are drawn to reflect the forecast path of the suspect storm. Also recall that outdoor warnings sirens are for OUTDOOR use and aren't designed to be heard inside well-insulated homes with TVs and air conditioners on and storms overhead, and definitely not while you are sleeping. That being said, we recognize that many people are close enough to a siren to hear it indoors.

Siren policy differs by county, and in Shelby County it varies by municipality. The best siren policy is one that limits the activation to times when the community in the path of the storm is the only one alerted. To review, these are the policies in place in Shelby County as of October 2:

• Bartlett, Collierville, and Germantown sound sirens for their cities (the entire city) only if the warning polygon intersects their respective municipal boundaries.
• Shelby County sirens (including Millington, Arlington, Lakeland, and unincorporated areas of the county) sound for the entire county when any part of the county is warned.
• City of Memphis sirens also sound for the entire city when any part of the county is warned.
• However, Memphis is nearing implementation of a brand new system (the change should probably occur in November) that will activate sirens in Memphis only for those areas that are within the warning polygon, plus any sirens outside the polygon that can be heard within the polygon. Details on this policy change can be found here.

A Tornado Warning was issued at 11:13pm last night (shown below) that clipped the eastern side of Collierville. No other part of Shelby County was affected. In fact, the storms had exited all but the southeast corner of the county. However, given the above-stated current policies, sirens should have sounded in Memphis, Shelby County, and Collierville.  Bartlett and Germantown were not affected.

This was a case in which, under Memphis' new policy, sirens would NOT have sounded for any part of Memphis, which is exactly the way it should be. In our opinion, Shelby County should also move to a policy that allows segmentation of the sirens. There really was no reason to warn Shelby Forest, Millington, Arlington, or Lakeland about the storm in Collierville. I checked with Bartlett officials and sirens were not sounded in their city - well done! I also heard multiple reports last night that Collierville siren activation may have been delayed, and then continued after the warning for Shelby County was cancelled at 11:23pm (10 minutes after issuance). We can't corroborate that firsthand however.

Despite the sometimes untimely pitfalls of technology and some initial setup, the best way to receive warning information specific to YOUR location is smartphone weather apps with location-based warning technology. They can be set to warn specific points, regardless of county, and provide the most pertinent information to your location. Because of potential for technology issues, we also strongly advise a secondary means of receiving warning information that will wake you. The best secondary source is NOAA Weather Radio. Despite being county-based (all radios in Shelby County would have alarmed with the Collierville warning above), it's better than nothing, especially when you're asleep and local media is turned off in your home. Outdoor sirens are not to be relied on to wake you up.

We appreciate those who have trusted MWN and our StormWatch+ technology to provide the precision warnings described above. If you're interested in checking it out, click the appropriate link below. It's a fraction of the cost of a weather radio and only alerts you when necessary - plus it will wake you up in the event of the most severe storms. The precision is best demonstrated by an individual who lives on the west side of Collierville and indicated that StormWatch+ did not sound last night. As it turns out, he was less than a mile west of the warned area and not in harm's way. The technology worked as advertised.

To conclude, we thank you for your patronage and support of MWN, we apologize for the radar issues, and we greatly appreciate the dedication of #TeamMWN! If you have any questions, comments, or issues to raise, we would love to hear from you! Comment on this blog, hit us up on social media, or drop an e-mail via our contact form.

Erik Proseus, MWN Meteorologist

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Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!

New siren activation policy coming to the city of Memphis

In Shelby County, there are five entities responsible for outdoor warning sirens to alert the populace that a Tornado Warning has been issued for Shelby County. Those are the cities of Memphis, Collierville, Bartlett, and Germantown, plus Shelby County. Each of the four cities are responsible for warning systems within their municipal jurisdiction, while the Shelby County Emergency Management Agency covers unincorporated Shelby County outside the aforementioned 4 cities, plus the towns of Arlington, Lakeland, and Millington.

Municipal boundaries within Shelby County. Bartlett, Germantown, Collierville, and Memphis all activate their own outdoor warning sirens. Shelby County is responsible outdoor sirens in unincorporated areas, as well as Millington, Lakeland, and Arlington city limits (grey).

As has been discussed on this blog before, Bartlett, Germantown, and Collierville all sound their outdoor sirens based on an imminent threat to their particular municipality, using the Tornado Warning polygon (or warmed area) issued by the National Weather Service. The city of Memphis and Shelby County have warned their entire area of responsibility for a Tornado Warning that includes any part of Shelby County. That policy will be changing in the city of Memphis.

Under an agreement with American Signal (an outdoor warning siren manufacturer), a brand-new state-of-the-art warning system has been developed and is in a test phase at the Memphis Office of Emergency Management (OEM), a division of Memphis Fire Services, which is responsible for activation of the city's 108 outdoor warning sirens. This new system, with multiple layers of redundancy and the ability to be triggered manually from multiple locations including via mobile by key personnel, will allow the city to modify its policy such that only the portions of the city that are under a threat of a tornado will be warned. Using software automation, polygon notification to specific areas of the city will be possible, thus reducing over-stimulation and siren fatigue of the public and ensuring that those that hear an outdoor siren during inclement weather in or very near the warned area as defined by the National Weather Service (NWS). (Note that the new system has not been implemented and no date has been set at this point for implementation.)

Location of the city of Memphis' outdoor warning sirens on Google Maps.

So how will the new system work? The software will ingest weather alerts as soon as they are issued by NWS-Memphis. When a Tornado Warning is issued that intersects any part of the city of Memphis, sirens will be automatically activated by the software. The sirens that sound will be those within the NWS polygon/warned area, as well as those that can be heard within a portion of the warned area, even if they are outside of the warned area. This "buffer" will mean that some areas that are just outside the warned area could hear the sirens, but it will significantly cut down on the overwarning of the entire population when a small section of the city is affected.

In addition to the software-driven activation, sirens can also be sounded (in whole or in part) manually. All activities of the system are also logged and displayed on the user interface so that key personnel will know when and which sirens activated and whether each siren is in a functional state.

The approach taken by Memphis is a bit different from those in Bartlett, Collierville, and Germantown. In the new Memphis system, parts of the city may be warned, while other areas are not, due to the large geographic area within the city limits. In the other three municipalities, the entire municipality is alerted if any part of their city limits are within the warned area. This approach, while it may still result in some overwarning, is certainly satisfactory given the smaller geographic area that these cities cover.

At this time, we are unaware of any planned modifications to the Shelby County policy, which warns all of their area of responsibility for any threat to the county (meaning a Tornado Warning for Collierville would result in sirens sounding countywide). Shelby County is responsible for sounding sirens for areas outside Memphis, Bartlett, Collierville, and Germantown, including Arlington, Lakeland, and Millington.

Our take

I am strongly in favor of the more modern, and conservative, approach to warning that is now being developed by Memphis and is in place in the other three municipalities. It has been nearly 7 years since the National Weather Service transitioned from county-based warnings to storm-based polygon warnings for Tornado, Severe Thunderstorm, and Flash Flood Warnings. The goal was to offer more clarity on areas the storm would affect and warn fewer people, only those most likely to be in harm's way.

While media outlets and, more recently, smartphone apps like StormWatch+ properly warn only those who are within the storm's path (polygon), there are several warning methods that a vast majority of the public still rely on that do not have this capability, including NOAA Weather Radio and many outdoor warning siren systems. These systems MUST be upgraded to produce a consistent message across warning methods. While the NWS has done their part to attempt to reduce overwarning, technology must now catch up or the efforts of the NWS will be moot. Too many warnings, whether from true false alarms or "perceived" false alarms due to poor communication, result in complacency by the public who are then put in greater jeopardy of injury or death. We say "bravo!" to those communities who are addressing the issue with modified outdoor warning siren policies.  (Now it's time to get NOAA Weather Radio on board.)

Erik Proseus, MWN Meteorologist

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Bartlett changes outdoor warning siren policy

As of June 1, Bartlett officials have modified the city's outdoor siren warning system policy to sound less often during adverse weather, just as Germantown did last fall and Collierville did previously. The primary reason for the change is an increase in complacency caused by perceived overwarning of residents, while still letting Bartlett citizens know when their community is threatened. Emergency Management Officials with the City of Bartlett feel that better public response to tornado warnings can be achieved by only sounding tornado sirens in the City Limits of Bartlett if the city is directly threatened by a storm capable of producing a tornado.

A new siren next to the water tower at Rivercrest Elementary School

As with Germantown and Collierville, Bartlett officials will only sound their outdoor sirens when a Tornado Warning (issued by the National Weather Service) intersects or overlays the Bartlett corporate limits, rather than anytime any portion of Shelby County is warned. Bartlett operates twelve (12) sirens with an effective radius of about 1 mile (or 3.5 square miles coverage) to warn their 58,000+ residents in the city limits. (Read the Press Release describing the change.)

In addition, the updated siren policy states that sirens will be sounded for 3 minutes, followed by a 2 minute pause, with the cycle repeated until the Tornado Warning is no longer in effect. This cycle will prevent the siren's mechanical parts from "burning up" that sometimes occurs when they have been running for tens of minutes with no break.

Background on polygon warnings

In 2007, the National Weather Service ceased warning entire counties for tornadoes, severe thunderstorms, and flash floods. Instead, these warnings are now issued on a storm basis. As we've described before, a polygon is drawn around the area in the path of these events, irrespective of county or state boundaries. However, many warning systems including NOAA Weather Radio still send alerts on a county-wide basis, resulting in larger areas being warned than the NWS intended via their polygon system. County-wide alerting result in "perceived overwarning" because people using those warning systems perceive a threat, when oftentimes they are not actually in the warned area. In the cases of Germantown and Bartlett, software designed by Earth Networks will show the polygon warning and the city limits and make the decision whether or not to sound the sirens straight-forward.

A Tornado Warning polygon issued for parts of Shelby County on January 23, 2012, is an example of one that would NOT require the sounding of Bartlett sirens, as the polygon does not touch the city limits. All other sirens in Shelby County would sound if this warning were issued again.

Caveats of outdoor warning sirens 

We cannot have a discussion of sirens though without talking about the main drawback of sirens. They are called OUTDOOR warning sirens for a reason! Sirens are to alert people outdoors that may be away from a news or weather source that dangerous weather is nearby and to seek additional information. They are not designed to wake you up in the middle of the night or be heard in a well-insulated structure over television, air conditioners, heavy rain or wind.


When indoors or asleep, ALWAYS have other sources of severe weather alerts that will grab your attention, such as our MWN mobile apps with StormWatch+ precision weather alert technology or a NOAA Weather Radio. In fact, everyone should have MULTIPLE ways of receiving life-saving severe weather bulletins, as any one can fail at any time.

Bottom line for those in Bartlett and Germantown - if sirens are sounding, you can expect that it is because your towns are within the tornado warned area and you should seek shelter immediately!  (Sirens in both communities are tested on Saturdays at noon, weather-dependent.)

Additional links/info:
Outdoor Warning Sirens page on MemphisWeather.net
Bartlett Fire Department page on City of Bartlett website
Bartlett Fire Department on Facebook

Outdoor warning sirens series on the MWN Blog:

• Part 1 (Role of the EMA)
• Part 2 (Role of warning sirens)
• Part 3 (The warning process & the future of warning systems)

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Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!

Germantown residents to hear outdoor sirens less often

Residents of Germantown, TN will be hearing outdoor warning sirens less often, but it's not necessarily a bad thing.  A couple of weeks ago, Germantown flipped the switch on new software and an updated siren policy that allows the city to make their own decisions about warning their residents and visitors during severe weather episodes. [Media release from the city of Germantown]

Background and warning policy

Using a $77,000 grant from the Department of Homeland Security, Germantown installed a complete weather system from Earth Networks (the company that owns WeatherBug) that includes a professional weather station, an HD camera, and Streamer RT software.  The weather station, located on top of fire station #3 adjacent to the Germantown Municipal Center, and HD camera, mounted on top of the city's tallest water tower, provide realtime local conditions and a great view of the sky to Germantown officials and anyone else who visits the WeatherBug website or mobile app. However it is Streamer RT that allowed Germantown to modify their tornado warning policy.

The city of Germantown and it's 17.6 square miles and 38,000+ residents are well-covered by 15 outdoor warning sirens with overlapping coverage. (On average, each siren has an audible range of just over a 1 mile radius, or 3.5 square miles.)  Until recently, Germantown followed the siren policy used by the rest of Shelby County and it's municipalities, which required that all sirens county-wide be sounded when any part of the county was affected by a Tornado Warning.

Now, using the graphical overlays available in the software, city dispatchers (whose duties include activating the city's sirens) will look at the display that depicts the Germantown city limits and the warning polygon issued by the National Weather Service (example below) and determine whether to activate the sirens. If the warning polygon does NOT include a portion of the city, sirens will not be sounded.  If any part of the city IS in the warning, sirens will be sounded. And once the warning is lifted for all of Germantown (even if it still encompasses other parts of Shelby County), sirens can be shut off.

Streamer RT software by Earth Networks provides Germantown dispatch and fire with current weather info, as well as warning polygons and the city limits, making the decision to warn the city, or not, an easy one.  In this case, sirens would not be activated. Image courtesy Germantown FD.

Fewer sirens = more trust in the system

In 2007, the National Weather Service ceased warning entire counties for tornadoes, severe thunderstorms, and flash floods.  Instead, these warnings are now issued on a storm basis.  As we've described before, a polygon is drawn around the area expected to be impacted by these events, irrespective of political boundaries (such as the red polygon in the image above).  However, many warning systems, including the NWS' own NOAA Weather Radio, still send alerts on a county-wide basis, resulting in larger areas being warned than the NWS intended via their polygon system.

County-wide alerting result in "perceived overwarning" because people using those warning systems perceive a threat, when oftentimes they are not in the warned area.  Besides weather radio, some commercial radio and TV stations still warn based on counties (though most are moving away from county-based warning), and in most places sirens still warn entire counties, including in Shelby County.  Because the cities of Germantown, Bartlett, and Collierville (as well as Memphis) activate their own sirens, they are able to break away from county-based siren activation simply by changing their internal policies.  Germantown is the first to do so.  Bottom line: going forward, when sirens sound in Germantown, residents can be certain that all or some part of their city is under a direct threat.

The process to transition to this policy actually began two years ago with a search by Germantown Fire officials for companies that would provide the tools to allow them to sound their own sirens.  When asked why Germantown decided to change their siren policy, Chief John Selberg summed it up this way: "I believe in being prepared without over-sensationalizing the emergency."  Ultimately, he expects the change in philosophy to "reduce complacency" since the sirens will only sound for actual threats to the city.

Caveats

Of course, we can't have a discussion of outdoor warning sirens without discussing the caveats.

First and foremost, never rely on sirens when indoors! It's very important to remember that outdoor warning sirens are called that for a reason - they are intended to alert people who are OUTDOORS to go inside and seek additional information on the threat.  Though Germantown's sirens have excellent coverage, if you are asleep with the air conditioner running and it is raining outside, it is doubtful that you will hear the sirens and you place yourself at risk.

Have a programmed NOAA Weather Radio with good batteries and, if you have a smartphone, install a severe weather app that will alert you (and wake you) in case of severe weather.  It should have a feature that will wake you for the most intense storms, allow you to program multiple locations, and preferably have a "follow me" feature for when you are traveling. We highly recommend our MWN app with StormWatch+, which fits the bill perfectly.

One of these methods in and of itself is not sufficient.  Always have multiple ways of receiving severe weather information.  Any one of them can fail at any time and you need a backup or two.

NOTE: Germantown sirens are tested on Saturdays at noon (unless the weather is threatening) and the sirens are all equipped with two-way communication which means the Germantown Fire Department knows, without activating the sirens or being on-site during a test, when a siren is not working properly.

Additional links/info:
Outdoor Warning Sirens page on MemphisWeather.net
Germantown Fire Department page on City of Germantown website
Germantown Fire Department on Facebook
"Weather system to limit siren sounds in Germantown" - Commercial Appeal

Outdoor warning sirens series on the MWN Blog:

• Part 1 (Role of the EMA)
• Part 2 (Role of warning sirens)
• Part 3 (The warning process & the future of warning systems)

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Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!

Outdoor warning sirens - part 3: the warning process and future of severe weather warning systems

This part of the series is a long time coming, but here it is!

In the first two posts of this series on outdoor warning sirens, we examined the role of the Emergency Management Agency during severe weather (including the activation of warning sirens) and the role of outdoor warning sirens themselves, which was to warn people who were outdoors of adverse weather.  In this post, the final in our 3-part series, we take a look at the future with regards to dissemination of severe weather warnings.

Background on the current warning process

In 2007, the NWS changed policy with regards to issuance of Tornado, Severe Thunderstorm, and Flash Flood Warnings to one based on the actual area threatened versus alerting entire counties. The NWS draws storm-based warnings, or "polygons," to highlight the expected path of the storm, with little regard for political boundaries (see the example from March 15, 2012 below).  This policy change had several intentions, one of which was to limit the area being warned, thereby hopefully reducing the perceived false alarm rate created by warning an area that the NWS is fairly certain will not be affected.


A Severe Thunderstorm Warning polygon ("storm-based warning") that identifies a small section of eastern Fayette Co. and a larger portion of Hardeman Co. as having a threat of large hail and damaging wind.  There is no threat of severe weather in Moscow or Middleton, even though there is in other parts of their counties.

Unfortunately, some 5 years after changing to storm-based warnings, NOAA Weather Radios, many outdoor warning siren systems, and even some local broadcaster's warning plotting software - the top 3 ways that citizens get severe weather information - still alert based on the COUNTIES affected, rather than the actual AREA affected. In the example above, the storms are moving northeast and, based on the yellow polygon, there is no threat to Moscow, Macon, or Middleton.  However, for those with Weather Radios in those locations, the alert tone would sound for all three towns.

Another example is below - this one even closer to home for many of you.  A Tornado Warning was issued shortly after 10pm on January 22, 2012 for southern Shelby County and northern DeSoto County. A squall line (not depicted) was approaching the river and a possible tornado was detected in the portion of the line that would affect the areas inside the red box.  Sirens sounded and weather radios alerted across Shelby County (excluding DeSoto County for this example).  Except for the southern part of the city and the eastern suburbs, there was no imminent threat from a tornado.  It could be said that although the NWS intended to only warn 242 sq. mi. of Shelby County, the sirens and weather radios ended up warning 754.5 sq. mi. or more than three times the area.  (In this example, there was sporadic wind damage reported, including a 105 mph gust that lifted a large roof from a commercial structure, all within the confines of the warned area.)

Outdoor warning sirens and the polygon warning

Now that the warning process is better defined, what is the future of weather warning dissemination?  Perhaps from these examples you can already start to see it: storm-based warning dissemination, rather than county-based.  While NOAA Weather Radio and some progressive county governments are beginning to make strides in this area, it will be some time before these systems are fully taking advantage of the benefits of the current storm-based warning program.

In Shelby County, TN, EMA Director Bob Nations indicates that they are "taking a serious look at new technology" and "exploring all the options" as they work towards system upgrades mandated by the Federal Communications Commission (FCC).  The FCC program, called "narrowbanding," opens up additional radio frequencies by essentially squeezing all of the current frequencies closer together in the radio spectrum. Narrowbanding will require a significant purchase of new hardware or upgrades to current infrastructure to meet a federally mandated January 1, 2013 deadline.  How does this affect the siren program?  The sirens are activated by radio frequencies that will change under the  narrowbanding program.

Part of the infrastructure upgrade will include new siren controllers on 111 warning sirens under the purview of the City of Memphis, which will be replaced with equipment that allows individual sirens to be sounded should a change in siren policy be made.  In addition to hardware, new storm-based warning software would also be required to activate individual, or banks, of sirens.  Nations is quick to point out that, while a change to siren policy might be possible with the new infrastructure, there would have to be agreement from policymakers who may not be willing to take the risk of storms remaining within the warned area.  Any changes to public policy will require the approval of those who write the policy.  Due to potential liability issues, any change to the current methodology of warning the entire county "would have to work every time," according to Nations.

So while (and until) the infrastructure upgrade and public policy process plays out (should there be a decision to move in that direction), citizens are strongly encouraged to consider all means of protecting themselves in the event of severe weather.  As discussed in part 2 of this blog series, outdoor warning sirens are not the "end all, be all" and are simply not designed to alert you if you are anywhere but outdoors, no matter what strategy is employed to sound them.

The future of weather warning systems

The best solution is that we move to faster-pace, more technological solutions that are available today. With the preponderance of smartphones and the capability of these devices to use GPS to determine your precise location,  it's no wonder their worth in targeted warning information is being utilized more and more.  There are several mobile apps that are available to warn you, in your specific location, to the threat of impending weather.  Of course, we highly recommend ours, but any will likely fit the bill depending on the features you are looking for.

The MemphisWeather.net app for Android and iPhone includes StormWatch+, a push notification system that will warn the user of severe weather watches and warnings that are issued for 2 pinpoint locations of their choosing.  It includes an audio alert that is loud enough to wake you up at night provided the phone is nearby and not silenced.  There are other services available as well, including some phone services that will call your registered numbers should severe weather threaten.

It is vitally important that you have multiple ways of receiving severe weather information, for your location if possible (or for your county if not), that will alert you at any time of day or night.  Outdoor sirens are one way, but they CANNOT be the only way.  NOAA Weather Radio is highly recommended as the baseline, but for even more pinpoint warnings that take advantage of the storm-based warnings issued by the NWS, you should add another service like StormWatch+ to your severe weather toolkit.  Severe weather can strike in any month and at any time of the day in the Mid-South.  "An ounce of prevention is worth a pound of cure."

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or follow us on Facebook or Twitter.

Outdoor warning sirens - part 2: the role of outdoor warning sirens

In part 1 of this MWN Blog series on outdoor warning sirens, we examined the role of the Memphis/Shelby County Emergency Management Agency (MSCEMA) with respect to severe weather, specifically the process by which outdoor sirens are sounded.  In it, you learned that the EMA is responsible for sounding all sirens in Shelby County except those in Bartlett, Collierville, and Germantown, who activate their own sirens. In part 2, we will focus on the purpose of the sirens, what they are intended to do, and more importantly, what they are NOT intended to do.

To recap, outdoor warning sirens are sounded continuously countywide whenever any portion of the county is included in a Tornado Warning issued by the National Weather Service (NWS). These outdoor warning sirens are NOT referred to strictly as tornado sirens for a reason: it is not fully descriptive of the mission they serve. From the MSCEMA website (http://www.mscema.org - emphasis added): "[Outdoor warning] sirens are designed to be an early warning device primarily for persons who are outside away from the television and/or radio."

As stated above and repeated many times by MemphisWeather.net, these are OUTDOOR sirens. They can be extremely useful if one is working or recreating outside and severe weather threatens. When sirens sound, you should seek out additional information on the threat.  This can be done in a number of ways, but the most common are to tune into local radio or television, check local weather websites or properly-equipped smartphone apps, and/or turn on NOAA Weather Radio (which should have also sounded an alarm when the sirens sounded).  If none of these additional information sources is available, you should take adequate cover until the sirens cease.

Photo credit: MWN
Smithville, MS warning siren

Sirens are NOT designed to A) wake you up at night, especially if storms are in progress with wind and rain creating additional noise or you are a heavy sleeper; B) alert you if you are indoors, especially in newer, more energy-efficient, and better-insulated homes with additional electronic noise (like air conditioners running, music playing, or television on); or C) reach every square mile of the county.  In fact, even outside, environmental factors such as the direction and speed of the wind, relative humidity, and air stability can affect where sirens are heard on any given day.

The bottom line is this: sirens are designed to alert those outdoors to the threat of severe weather and encourage them to seek additional information.  Do NOT call local authorities, including the EMA, if you aren't woken up by a siren or you didn't hear it inside, UNLESS you are fairly certain that a nearby siren that you have heard under those circumstances before is not operating properly (i.e., fails to sound).  Click here for a list of all sirens and the person to contact in case of siren failure ONLY.

In the third installment of this series, we will examine the future of warning technology - from sirens to smartphone apps - in an age of polygon warnings.

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Outdoor warning sirens - part 1: the role of the EMA during severe weather

Recently I had the honor and pleasure of sitting down with several individuals from the Memphis/Shelby County Emergency Management Agency (MSCEMA), including Mr. Bob Nations, Director; Mr. Levell Blanchard, Deputy Director; Mr. Tommy Thompson, Outdoor Warning Siren Coordinator; and Mr. Keith Butler, Dispatcher and "technical guy" for the EMA's many electronics and communications systems.  I also was fortunate to tour the EMA's Emergency Operations Center in Midtown. The purpose of the meeting was to discuss the outdoor warning siren system in Shelby County, learn more about how their systems and processes work during severe weather, and perhaps find out if any changes to the warning process were in the works.  I came away impressed with both the responsibility and recent accomplishments of the EMA personnel.

This is the first in a 3-part blog series on the outdoor warning sirens in Shelby County.  This first entry examines the role of the EMA during severe weather, including the sounding of the sirens.  The second installment will focus on the intent of outdoor warning sirens, what they are designed to do, and NOT to do. The answers may surprise you. We'll conclude with a look at the future of warning technology, including sirens, in part 3.

Photo credit:
MSCEMA.org

One of the most visible (or audible perhaps) roles of the EMA is the sounding of outdoor warning sirens. I've discussed the policy of sounding the sirens previously on this blog, but the bottom line is this: currently, all sirens in Shelby County sound continuously throughout the duration of a Tornado Warning if any part of Shelby County is included in a National Weather Service-issued Tornado Warning.  That means if Millington is under a tornado warning, Collierville's sirens sound (more on how this works below).  Click here for a map of siren locations in Shelby County or click here for a list of all sirens..

Though the siren system was originally designed to warn the public of air raids during World War II, then nuclear fallout during the Cold War, the practice of using sirens to warn of severe weather dates back decades, well before the NWS began issuing polygon warnings that didn't encompass entire counties. That NWS policy change occurred in 2007.

The EMA Emergency Operations Center (EOC) is staffed by dispatchers around-the-clock, handling all sorts of calls for emergency response.  Their busiest period is typically during severe weather. In the EOC, a computer running weather messaging software is constantly ingesting bulletins from the Memphis NWS office via satellite (with internet backup) and processing them for any watches and warnings.  (Backup systems are also in place in case of a failure of the primary computer, including Weather Radio, statewide emergency communications, and local broadcast television.)  In the event of a watch or warning, a pop-up on the dispatcher's terminal immediately displays the text of the alert.

Photo credit: metrolic.com

If the alert received by the dispatcher is a Tornado Warning for any part of Shelby County, the dispatcher will then activate the sirens throughout Shelby County - except Bartlett, Collierville, and Germantown - using two different systems.  The three municipalities named are responsible for activation of the sirens in their own jurisdictions. Telephone calls are placed from EMA to dispatchers in each of these three suburban cities to make them aware of the warning.  Bartlett, Collierville, and Germantown will typically also sound their sirens based on the information they receive.  The sirens sound countywide until the expiration time of the warning or the cancellation of it, should the NWS cancel the warning prior to the original expiration time.  All of Shelby County must be clear of any Tornado Warnings before the sirens will be shut off.

Stay with us later this week as we examine the use of outdoor sirens in part 2 of this 3-part blog series.

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A word on Tornado Warnings and outdoor warning sirens

There is always a lot of confusion regarding the sounding of "tornado sirens" during severe weather.  Here is some information that might help:

1. Tornado Warnings are not issued by county, they are issued by polygon, meaning that the track of the storm is identified and a box is placed around the track.  Whatever counties that box intersects (no matter how much or what part of the county), the county is considered "warned."
2. In most areas, including Shelby County, outdoor warning sirens are activated by Emergency Management Agency officials or other designated agencies, such as area fire departments.  The sirens are almost always sounded COUNTY-WIDE when a polygon/warning touches that county, even if the entire county is not in the path of the storm.
3. The sirens will continue until the warning expires or is cancelled (sometimes even continuing until the original expiration time, even if the warning is cancelled early).  They do not stop when the threat has passed the immediate area if the warning is still in effect.
4. The sirens are OUTDOOR warning sirens.  They are meant to alert people outdoors to go inside and find out where the threat is then take cover.  Please don't complain that "I didn't hear the sirens" when you are inside with the TV or entertainment system on, etc.  If you are inside and there is a threat, be tuned in to local media or other information trusted sources, especially if you know you can't hear sirens well inside your home.

There has been a great deal of confusion on the subject and a sense by the public of "overwarning," however this is the way it works (for now). If a warning is in effect for Collierville and you are in Millington, your sirens will sound.  Do NOT become siren-weary or start ignoring the sirens because "the storms are never in my area" or "those things always go off for nothing."  The next one could be for a storm approaching your home!

In the meantime, hopefully city and county officials will understand the issues that county-wide warnings pose and come up with a reasonable solution.  They are out there, but some are very costly to implement.  For more information on the warning sirens in Shelby County, check out MWN's new Outdoor Warning Sirens page.

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