Activating sirens for severe winds

[James Hilger]

If there was a way to change the sound-pitch of the siren to distinguish the two, then i would be all for it.

 

[James Hammett]

If there was a way to change the sound-pitch of the siren to distinguish the two, then i would be all for it.

Some municipalities do this if their sirens support it. Not all sirens do, though.

 

[Jeff Snyder]

Interesting topic - and one that I'm fairly passionate about. I grew up in Dakota County, MN and they sound the sirens for everything. Everyone I know that lives there hears the sirens and ignores them because of this. One of these days, a large tornado will bear down in Dakota County and I get the feeling that people won't react to the sirens.

Small world -- I also grew up in Dakota County, MN (southeastern Twin Cities metro for those who aren't familiar). The "sound the sirens for every severe thunderstorm warning" was, IMO, ridiculous. Like you, everyone I knew essentially ignored the sirens as a result of the high frequency of their activation compared to the threats that verified. Sounding the sirens for a storm with 0.75" hail (this was well before the 1" hail severe criterion change) that was NOT a threat to life and only a very small threat to property only added to the "overwarning" issue.

I strongly support using the sirens only for short-term weather events that are a significant threat to life and property. Certainly, I think we all agree that sirens should be sounded for tornado-warned areas (and bonus points to the EMs that selectively activate sirens based on meso location instead of for an entire county, though I'm not sure how polygon warnings are used by EMs in their 'siren activation' decision making). I also think that storms with winds >80-90 mph also pose an enhanced threat to life and property; certainly, a bow echo with 90-100+ mph winds can do much more damage and pose a greater risk to life than a weak, short-lived tornado. I'd also say that >2.5" hail can also pose an enhanced threat to life and property, but, aside from ground observations, it's not particularly easy to anticipate max hail size. As such, I support using sirens for tornado threats and high-end wind events.

 

[Ryan Pfeifer]

Sirens absolutely should be sounded for 80mph winds. I don't think anyone in Omaha has died from a tornado the past decade, but I know there's been at least one death from straight line wind events, and I think more. It seems to me more often than not that if 80mph winds go through a city someone dies from a tree branch falling on their car. Winds only kill about 30% less people a year than tornadoes. And as for psychology of it all, I think lay people could very easily feel like they're going through a tornado with winds that strong, and at very the least be impressed/understand why the sirens would be sounded. I know when I was in a 90+mph wind event it got reported as a tornado. Plus, it's a going to be a much more accurate warning and have larger coverage of people that actually experience what the warning was issued for. Anything less than 80mph doesn't quite seem dangerous or impressive enough for these things to hold true though, so I wouldn't do it for any less than 80 like many have mentioned. Omaha sounded the sirens for the last wind event and it seemed silly because the winds were only in the 70mph range. But a few years ago when we had a 80-90mph event it was the talk of the town for days and there was a fatality.

http://www.weather.gov/om/hazstats.shtml

 

[Kate Pfeister]

For anyone that remembers the durecho/inland hurricane that went through parts of missouri and illinois in May 2009...

When the durecho came through Jackson County, Southern Illinois University took a big hit. SIU is a very heavily wooded college campus in the middle of Shawnee National Forest, lots of huge trees scattered about the campus, with a larger forest in the middle of campus with paths heavily travelled by students.

Although our county wasn't under a tornado warning, the sirens did start about 2 minutes before the storm hit. We lost power before the storm hit, and the sirens cut out at the same time.

Ironically, it was also the weekend of everyone moving out, so there we lots of people outside, walkng around. The sirens sounded, and most people took cover in the dorms.

After the storm passed, there was widespread damage across campus. We lost something like 10% of the trees on campus. There were many damaged cars, many totalled by trees or branches falling on them. A few cars were completely engulfed by trees, to the point you couldn't even see them through the leaves.

I'm convinced that if our sirens hadn't sounded, someone would have been hurt or killed taking cover in their cars, or just walking around campus.

I'm not sure what the laws are in Illinois regarding sirens, but I'm torn. I'm really glad they did go off when the durecho came through, but I do fear that people will take them with even less care then they do now...

 

[MatthewCarman]

I talked to a friend at school who was sound asleep Sunday Morning untill a tree fell on top of his house and did $20,000 of damage to his home. Thankfully he is alright and he had insurance so his home will be fixed. The tree he said was about 40 feet so this was a big tree. Had it come into his bedroom he could have been injured or killed. I am not sure if the sirens went off in west Des Moines where he lives but if the winds are strong enough to knock down big trees then maybe they should be sounded for 70 MPH winds. I still think it is better to sound them for 80 MPH winds but I also don't want to see anyone get killed.

 

[Robert Dewey]

Why not just sound the sirens for 58 mph winds then?

I think there's a significant difference between 58MPH and 80MPH.

 

[Jeff Duda]

I think there's a significant difference between 58MPH and 80MPH.

Indeed there is. An 80 mph wind applies 1.9 times as much force to an object as does a 58 mph wind. The comparison involving 70 mph is:

70 to 58: 1.46x as much force
80 to 70: 1.31x as much force

I don't think sirens should be necessary for 70 mph winds as I already stated in my first post, but when you get up to 80 or more, I start to think that sirens would be warranted due to the possibility of widespread destruction. Thus I must have some sort of line I draw between 70 and 80 mph (or somehwere near 80). What thresholds do you all think should surely warrant sirens (for severe straight line winds only)?

 

[Darren Addy]

Penny makes a good point, but one that goes to the heart of the problem: Communication. When the sirens go off, people assume "tornado warning" but the sirens can be used for multiple purposes. When the same sign or signal has multiple messages the result is (most-likely) miscommunication. However, if the ACTION required for each of those messages is the same (get yourself inside and/or in the basement) or at least "turn on your radio to find out what is going on" then the message signal has served its purpose.

Kate's point goes to the heart of why sirens should sound in the event of high wind. Saturday night near Kearney a storm complex with high wind moved through at about 10 PM. The streets and yards were filled with (a lot of inebriated) revelers for our annual "Cruise Night". The wind was powerful enough to flatten 32 miles of 230-kilovolt high transmission power lines. A house SE of Pleasanton had its roof torn off by the straight line winds. Winds that strong can snap significantly large tree limbs (a threat to life and limb) and even getting hit by windblown debris (like lawn furniture) could cause a painful injury.

If we have the technology to see such threats coming, then it certainly makes sense to warn citizens of them. Whether citizens heed the warning or not is their problem, and doesn't make the warning any less useful to those who do.

http://www.kearneyhub.com/news/local/article_9c317006-9356-11df-98f5-001cc4c002e0.html

 

[Robert Dewey]

What thresholds do you all think should surely warrant sirens (for severe straight line winds only)?

I'm thinking 75-80MPH.

Our county activates at 70MPH, which they've already used twice this year for severe events. That's fine if those verified, but they didn't. The highest gusts I saw reported for a particular event was 65MPH (although there were several reports of 60-65MPH count-wide). Upstream reports didn't indicate the 70MPH threshold either, and the storm certainly wasn't strengthening (most reports were 40-60MPH, with a few 65MPH gusts noted).

As a side note, our county's policy is new (enacted after a widespread 80-90MPH event occurred a couple years back). However, it does in fact cause confusion... and our TV meteorologist was confused as well, stating [paraphrased] "I'm getting reports that sirens are going off in Oakland county. I'm not sure why, but let me re-iterate that there is NO tornado warning."

 

[Charles Loring]

I could see a town sounding the alarm for winds of >75 since that is the same as a weak tornado and also hurricane force winds and also blaring it for hail the size of golf balls. If out in that, both of those could do serious damage to you. I'm not sure what our towns siren criteria is, I will have to find out though.

 

[Darren Addy]

re: 70mph threshold

That's fine if those verified, but they didn't.

By that logic we should also regret all tornado warnings unless they "verify". I think that most people would rather be able to take action if one was likely or eminent.

 

[Robert Dewey]

By that logic we should also regret all tornado warnings unless they "verify".

...and we do, it's called a FAR.

Also, there was nothing to indicate widespread >70MPH winds. The reports were consistently 40-60MPH (a good case for sub-SVR reports being important). The storm wasn't strengthening. There was nothing to warrant the >70MPH warning IMO.

 

[James Hammett]

Also, there was nothing to indicate widespread >70MPH winds. The reports were consistently 40-60MPH (a good case for sub-SVR reports being important). The storm wasn't strengthening. There was nothing to warrant the >70MPH warning IMO.

The wind speed figure given in the warnings always seems to be worst-case and it isn't updated as the storm winds down. While giving the worst-case wind speed is understandable (given microbursts and such) it's another reason to be sure that the siren-sounding criteria is sufficiently high.

As far as verification goes, I have to wonder if false alarms for wind are less acceptable to the public than for tornadoes as people are more familiar with the graphic destruction a tornado can cause (though localized).

 

[Justin Wiley]

I think there's a significant difference between 58MPH and 80MPH.

Of course there is. Why do we have warnings for 58mph then?

My whole point is this will create confusion. Severe Thunderstorm warnings that don't require sirens (58-79 mph) and those that do (80+ mph). In essence, it will devalue the Severe Thunderstorm warning below the siren threshold. That's fine I guess but then you might as well up the Severe Thunderstorm criteria then.

What about non-thunderstorm type wind events? High Wind Warnings? Wind Advisories? Granted the risk of death may appear less (namely because these events are more rare than thunderstorm events) but you can still get injured outside in 60 mph non-thunderstorm related wind gusts by flying objects and possibly decent sized limbs that may fall down.

Common sense is the key. I think the system now is just fine. Unless I'm missing elevated numbers on severe thunderstorm-related deaths or something.

Let's also remember that lightning kills more people per year than tornadoes or straight-line wind events. Do we need to sound the sirens when lightning is imminent as well?