I May be the Reason You Get Woken Up

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Nyquist

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Or even started during the evening hours because of a tornado warning. I just finished my share of a technical warning decision paper with steps for detecting very transient tornadoes in certain thunderstorm systems. All in all, in some instances the critical success rate was above 90% for the write-up as a whole. That includes the detection rate, correct detection and false alarm rates. I don't know if many of you will consider that cool or not, but I've spent the past 4 years of my life working on this. To see it come full circle is nice.
 
Hey, I give you a \:\! ! I say the more info the better. I'm fascinated by the DOW program that has been collecting data on tornadoes each season. Those who complain about warnings have never seen the results of something like the Xenia Tornado of April 3, 1974.
 
I'm glad that people spend lifetimes studying this type of thing. Because tornadoes are still a mystery, they can pop up out of nowhere. The more warning the better. If everyone is huddled in the basement most likely everyone will survive.
 
Where is storm chasing Drew?? Good work in the environmental lottery last minute decision warning process (I think that's what I'm reading). I'm glad tornadoes are a very rare event here.
 
I would like to see some numbers on towns with and without those infernal sirens. Our local idiots are sounding them when ever there is a severe thunderstorm. This is to warn those out in a severe thunderstorm that there might be a tornado. They say if they wait until there is a tornado, there isn't enough time for a warning. I figure it won't be a year or 2, before everybody will ignore the frequent false alarms. Maybe our officials don't know enough to come in out of the rain, but most of us do. The systems are expensive and obtrusive. Are there figures showing they do any good? In the real world, are people getting timely warnings they will heed and take shelter?
 
 Originally Posted By: Johnny
If you live in tornado alley and have been through one, you thank God for those pesky sirens and folks like Nyquist.
Yep. We had a "little" F2 tornado skip through our town last year. A little tornado isn't so little when it's just down the block. I'm very thankful for both sirens and weather radios.
 
Passive tornado warning system: giant whistles Put them on telephone poles 50 feet apart all around the city. When a tornado hits one of them, it sucks air through and sounds the alarm. Do twisters have a recognizable acoustic signature that can be detected from miles away? There must be some kind of vibration they give off, in the subsonic range. And, it would be concentrated in one small area.
 
 Originally Posted By: Gary Allan
Where is storm chasing Drew??
Right here! I saw 4 tornadoes near Roll, Oklahoma last Sunday, and a nice rapidly rotating classic supercell near Wheeler Texas on Saturday. Good work Nyquist. So is this a system implemented by doppler radar? I have GR3 on my laptop in my car, and the storm on Sunday was nuts because the main mesocyclone which produced a large wedge to cone tornado, had a very stout velocity couplet. On the RFD gust front, 3 additional small mesocyclones each produced a tornado and only one showed up barely on radar, probably because 2 of the naders were satellites. Do you storm chase at all?
 
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 Originally Posted By: oilyriser
Do twisters have a recognizable acoustic signature that can be detected from miles away?
Yes. That of a freight train.
 
 Originally Posted By: Johnny
If you live in tornado alley and have been through one, you thank God for those pesky sirens and folks like Nyquist.
I am not going to go hide under the bed every time we have a thunderstorm. We haven't had a tornado here in over 30 years, yet they are sounding the sirens dozens of time a year. Who remembers the story of the boy that cried wolf?
 
 Originally Posted By: Drew99GT
 Originally Posted By: oilyriser
Do twisters have a recognizable acoustic signature that can be detected from miles away?
Yes. That of a freight train.
http://www.esrl.noaa.gov/psd/programs/infrasound/FAQ.html "What is the latest in tornado researching technology? ETL is currently working on a system for detecting very low frequency sounds from tornadoes as a system complementary to Doppler radar. It continues to show promise as a technique for filling detection gaps and improving prediction times. This is a "work in progress". NOAA supports or has supported a number of other technologies, including: 1. A seismic detection technique to warn of and locate tornado touchdown points. 2. An electromagnetic detection technique (with a hope that something like a low-cost tornado "smoke alarm" could evolve) 3. A pressure detector prototype suitable for large scale deployment in tornado prone areas to provide needed knowledge about the cores of tornadoes." Interesting stuff.
 
Thanks for your work! I must say that around these parts, they do sound the siren more often than they should - they're being too cautious and it's caused the public to build up a tolerance to the alert. It's tough, too when the county is big enough that a tornado is ten miles away and headed further still, the sirens still fire up all over the county.
 
I have no problem with them sounding the sirens when a tornado is in any part of the county I am in. Or even in an adjoining one. Every severe thunderstorm when there isn't a tornado in the whole state is just plain stupid.
 
Labman, you have to understand that the vast majority of tornado warnings are issued as a result of rotation visible on Doppler radar, and not an actual sighted tornado. In reality, the science behind tornado genesis is still very vague. What is it, something like 20% of supercell thunderstorms (a storm with a persistently rotating updraft) go on to produce a tornado. Doppler radar technology has come a long way - we can see the broad rotation within a thunderstorm - whether it actually goes on to produce a tornado is still largely a mystery. Now, a supercell storm that's producing a large violent tornado that truly is capable of leveling structures and killing people will show very strong rotation at the lowest levels of the atmosphere and a tornado warning is warranted (and that on average is a rare occurrence). However, weaker radar signatures have been consistent with fairly strong tornadoes, and as such, NWS meteorologists are doing their job by issuing warnings when any kind of broad based rotation, and other radar signatures, are present. It may be a nuisance when a warning is issued during the night, but it might also save your life. Best thing to do, especially if you're "tolerant" of warnings, is to have a very quick plan of action if a tornado actually hits. Lowest level of the structure you're in, and pack the outside of your body with sheets, blankets etc.
 
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There are a lot of failure mechanism dealing with tornadogenesis that we're only now discovering. Tornado warnings have improved vastly over the past 10 years. I want to thank you all for your tax dollars that helped fund the WSR-88D upgrade over 15 years ago. That has helped save more lives than you know. A classic radar signature with a bounded weak echo region (BWER), very strong and deep mesocyclone, and a tornado vortex signature (TVS) will only give you a verified tornado about 40% of the time. That means there is something else that may be missing. Studies resulting from a big experiment in 1995 have identified some new techniques, but also more failure mechanisms. One theory which I firmly believe in is that the temperature inside the thunderstorm--particularly the downdraft--has to be just right relative to other factors. If it is too cold, there will not be a tornado. Unfortunately the more answers we find, we end up with more questions. A second big experiment is going on now and again next year that deals with classic supercell tornadoes. My research area focuses on non-supercell tornadoes which are very, very hard to detect with enough lead time to warn people. My focus is on quasi-linear convective systems (QLCS) and their associated meso- and misovortices tornadoes. At times you may have 3 or 4 on the ground at once in addition to 70+ mph straightline winds. The method I have may also work nicely for very small, embedded supercells in those QLCSs. It just needs more research.
 
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