Warning Sirens

[Brandon Smith]

The only way I could see using a siren for severe thunderstorm warning is using that air-horn feature I posted above. Something that sounds nothing like a wail or high - low pitch. IMO, to have steady blasts of the "air-horn" would be easy enough for outdoor events.

There are two types of tornado sirens, electro-mechanical and electronic. Electromechanical are your traditional type of sirens that have been used since the cold war era and used in many areas for severe weather warning. They use a motor to power a spinning slotted centrifuge that pulls in air and releases it through a slotted drum that surrounds it. When the slots are aligned, air is forced through at a high velocity, making a low "whistle."

The newer sirens on the market are electronic sirens that use a high-powered speaker to emit a siren like sound, along with text either spoken by a person or a computer. These sirens can be heard for a good mile. From what I've read, these type of sirens can be programmed to give out a variety of different tones, along with messages pertaining to the emergency at hand. For example, they can be told to either give off a severe thunderstorm warning or a tornado warning. This can be extremely helpful in that there is not confusion as to what event is taking place.

 

[John Wetter]

Dakota County, MN blows the sirens for SVR warnings. The greater twin cities area will blow the sirens for SVR storms producing >75mph winds. In the mid-late summer, some cities will blow sirens just for their particular city on a SVR if they have a town festival going on. This happened recently which I thought was a good use. Like most, I think it's a mistake to blow sirens for everything.

-John

 

[Danny Neal]

There are two types of tornado sirens, electro-mechanical and electronic. Electromechanical are your traditional type of sirens that have been used since the cold war era and used in many areas for severe weather warning. They use a motor to power a spinning slotted centrifuge that pulls in air and releases it through a slotted drum that surrounds it. When the slots are aligned, air is forced through at a high velocity, making a low "whistle."

The newer sirens on the market are electronic sirens that use a high-powered speaker to emit a siren like sound, along with text either spoken by a person or a computer. These sirens can be heard for a good mile. From what I've read, these type of sirens can be programmed to give out a variety of different tones, along with messages pertaining to the emergency at hand. For example, they can be told to either give off a severe thunderstorm warning or a tornado warning. This can be extremely helpful in that there is not confusion as to what event is taking place.

Around here we have the older Thunderbolts 1000's, Federal Signal 2001, and the T-135's. While I love the sound of Thunderbolts, I think it may be time to upgrade to the newer Whelen's or Federal EOWS 612 and especially the ones that can have audio displayed over them. It would make a lot of sense to have tornado sirens that actually read out the reason why they are going off....but like with everything else....do people really see it as big deal, and who would really want to pay for it?

 

[Darrin Rasberry]

The city of Wichita Falls, at least as of 2002, sounds sirens for winds in excess of 80mph (source was a TV met at the time).

 

[David Poch]

On a side note, am I the only one who becomes hypnotized by tornado sirens?

I use to go out at noon every saturday just to listen to them during the test. Now that I live out in the sticks I don't get to hear them anymore.

I have only ever heard them for tornado warnings and when I was a volunteer fire fighter they would go off for the calls. After the Plainfield tornado in 1990 they quit blowing them for fire calls.

 

[Jesse Risley]

When I was growing up, my hometown of Streator, Illinois would occasionally activate the sirens (good ol' yellow Thunderbolts) for severe thunderstorm warnings. They discontinued the practice 15-20 years ago due to not only confusion but also the eventual apathy that Mark was referring to in his post.

As far as I know most of the communities in this neck of the woods will only activate the sirens if they believe the threat of a tornado is imminent.

 

[Jim Saueressig]

Federal EOWS 612

To my knowledge Federal EOWS 612's were discontinued years ago, they could only be purchased through special order a few years ago for replacements.

 

[Danny Neal]

To my knowledge Federal EOWS 612's were discontinued years ago, they could only be purchased through special order a few years ago for replacements.

You are right, I know they had a couple in Ohio when I went there and one of them went off and it was LOUD! lol

 

[sebenste]

Great topic. This will probably stir a hornet's nest, but...

I've thought about this topic a lot, since I am responsible for 30,000 people on our Northern Illinois University Campus during bad weather.
Since our shooting here, getting safety right has been even more of a pressing concern; they're going to be hiring an EM soon.

Our city (DeKalb) did not have a good tornado policy when I started here nearly 10 years ago. We are on the west side of our city--DeKalb---and back then, the city policy was not to ring the sirens until NIU got hit. And, only sound the alarm on the Civil Defense radio...if there's time. At the time, they didn't want to change policy, so I junked the CD radios for those new NOAA Weather Radios with this weird thing called "SAME" on it.

Well, time and technology and attitudes have greatly changed here. Now, the city-operated sirens and policy for severe weather for them is this...hit the sirens:

1. If any part of DeKalb is in the tornado warning polygon. I hooked them up with GRLevel 3 to make that a reality. They love it, and it's monitored 24/7 in the fire station; they're the guys in charge of "the button".

2. If a tornado is sighted by a TRAINED spotter; officers and fire departments can see across the city and can quickly verify/debunk the report. This is regardless if a tornado warning is in effect.

3. Any winds seen that are causing tornado-like damage. In other words, if lives are threatened by the damaging winds of a tornado or microburst/straight line winds of 80+ MPH, hit the sirens!

4. If Gilbert says "hit the sirens". Thankfully, that will theoretically never come to pass due to #1-#3 being in effect.

This increases the false alarm ratio above zero, but of course it also gives what I believe to be the best balance of warning time and false alarm levels.

Now, having said all that, sirens cost up to and higher than $20,000 PER SIREN. And, they can only be heard outdoors due to noise from A/C units, TV's, Ipods, etc. My suggestion (gulp): dump the tornado sirens except where there is a considerable amount of outdoor activity, and get $30 SAME-equipped NOAA All-Hazards radios instead. We have 3 stations covering our city, including a transmitter in town. We have no reception problems, to say the least, within the city that I know of.

 

[Danny Neal]

Gilbert I would tend to agree with you about the sirens being dumped in principle(everyone SHOULD have the NWR regardless), however, with so many people always outdoors, either working or for sports or recreation, I don't know if this will ever happen.

Wow 20,000 per siren? I didn't know they would be THAT expensive. I guess that could be a reason why most rural communities/poor areas do not have them. It was kind of shocking to hear that only recently Nashville, Tennessee, put in reliable sirens.

 

[Dann Cianca]

Haha, growing up in Butte, Montana, I only heard the sirens for two reasons:

1. The 9PM siren. Every night at 9PM, the siren rang once ... my parents always used it as a curfew reminder for me when I was playing outside.

2. Volunteer firefighter call-up.

While not impossible, the tornado threat there is very low. I saw a cold-air funnel once along with a summer supercell that had a weak wall cloud... that was in 23 years.

 

[Josh Murfield]

Here in Lincoln, NE they only sound the sirens when this part of the county- including the city of Lincoln- are in an actual tornado warning. Whether it be a spotter verified tornado or just a doppler indicated tornado they will sound the sirens. However they are good about not crying wolf- if a TOR warned storm is in another part of the county and not a threat to the city of Lincoln they do not sound the siren, and they never sound it for any other reason. Heck, if they sounded it for SVR warned storms for the threats of high wind or large hail we'd be hearing that siren so often that nobody would take it seriously anymore.

 

[Kem Poyner]

sirens

With the advanced technology today, I am suprised that each home in tornado alley is not equipped with a personal alarm. Sirens do little for rural areas and heavy sleepers. A weather radio has its issues. Like dead batteries, needed to carry it from room to room and not being turned on during a suprise tornado.
A home wired for devises simular to smoke detectors would be best. They could be activated by phone lines or something.

 

[Danny Neal]

Usually my areas policy is if a tornado is reported with 20 miles of the district I am in they will set off the sirens. I was in the polygon on June 7th, but the storm was still 40 miles away so we remained silent. Once the storm was about at I 57, the district set off their warning sirens because it was within the 20 miles. I know some towns set them off regardless, because even when I was driving south to get to the storm I was passing by tornado sirens (different district)

 

[rdale]

With the advanced technology today, I am suprised that each home in tornado alley is not equipped with a personal alarm.

Smoke alarms are nearly 100% accurate. Tornado Warnings are nearly 75% INaccurate. When that numbers gets higher, then we can talk about mandating them in houses...