Thursday, April 19, 2012

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 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."

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

1 comment:

Lisa said...

Thanks for the info. Until alerts become storm based, we will have problems with people taking them seriously when they need to.