[Clough]

Hi, All!

I'm wondering if there is a set standard as to how public sirens will sound in the United States if it's a tornado or thunderstorm warning.

Is there a set standard?

Thanks!

[Wondergirl]

From Wikipedia --

Usage in the United States
Federal Signal SD-10.

Sirens began to replace bells for municipal warning in the early 1900's, but became commonplace following America's entry into WWII. Most siren models of this time were single-tone models which often sounded almost an octave higher in pitch than their European counterparts. Dual-tone sirens became more common in the 1950's, but have been used in some areas since about 1915. During the Cold War, standard signals were used throughout the country for civil defense purposes, referred to as "alert" and "attack." Volunteer fire departments generally used a different siren signal. Many towns, especially in California and New England, used coded air horns or diaphones for fire calls and reserved sirens for civil defense use.

Today, signals are determined by state and local authorities and can vary from one region to another. The most common tones produced by sirens in the United States are "Fast Attack (Fast Wail)" "Alert" (Steady), "Attack"(Wail), and "High-Low (Hi-Lo)." Only a few siren models are capable of producing the hi-lo signal.[citation needed] Other tones include Chimes, Whoop, Pulse, Air Horn, Hazard, & Scream.

The U.S. Federal standard regarding air raid signals is defined in FEMA's Outdoor Warning Systems Guide, CPG 1-17[5], published on 01-March-1980, which describes the Civil Defense Warning System (CDWS) and its warning signals. The language was slightly revised by FEMA's National Warning System Operations Manual, Manual 1550.2[6] published 2001-03-30:

* Attack Warning--A 3 to 5 minute wavering tone on sirens or a series of short blasts on horns or other devices. The Attack Warning signal means detection of an actual attack or accidental missile launch. Take protective action immediately. The Attack Warning will be repeated as often as deemed necessary by local government authorities to obtain the required response by the population, including taking protective action related to the arrival of fallout. This signal will have no other meaning and will be used for no other purpose.
* Attention or Alert Warning--A 3 to 5 minute steady signal from sirens, horns, or other devices. Local government officials may authorize use of this signal to alert the public of peacetime emergencies. Besides any other meaning or requirement for action as determined by local government officials, the Attention or Alert signal will indicate to all persons in the United States, "Turn on your radio or television and listen for essential emergency information".
* A third distinctive signal may be used for other purposes, such as a local fire signal.
* No all-clear signal is defined by either document.
* CPG 1-17 recommends that a monthly test be conducted, consisting of the steady Attention signal for no more than one minute, one minute of silence, followed by the Attack signal for no more than one minute.
* A "growl test" signal is described conceptually by CPG 1-17 for use when a siren must be tested more often than once a month. This is typically a 1-second burst of sound to verify the proper operation of the siren without causing a significant number of people to interpret the test as an actual alert.

While the tones used vary in some locations, the most common tone, the "Alert," is widely used by municipalities to warn citizens of impending severe weather, particularly tornadoes. This practice is nearly universal in the Midwest, where intense and fast moving thunderstorms occur frequently. The sound of the "Alert" is a steady continuous note. In seaside towns, the "Alert" may also be used to warn of a tsunami.

The "Attack" tone is the iconic, rising-falling sound of an air raid or nuclear attack, frequently heard in war movies. It was once reserved for immanent enemy attack, but is today sometimes used to warn of severe weather, tsunamis, or even fire calls, depending on local ordinance.

There is no standard "Fire" signal in the United States, and while the use of sirens by volunteer fire departments is still common, it is diminishing. In the dry areas of the western states, residents may be required to shut off outdoor water systems to ensure adequate pressure at fire hydrants upon hearing the signal. The fire signal can vary from one community to another. Three long blasts on a siren is one common signal, similar to the signal used by volunteer brigades in Germany and other countries. Other locales use the hi-lo signal described above, and some communities (particularly in New England and northern California) make use of coded blasts over a diaphone or air horn for fire signals, reserving the use of sirens for more serious situations. Some cities use the Attack tone as their fire call. Some communities make use of an "all clear" signal, or sound separate signals for fire calls and ambulance runs.

[cdad]

Here is a few links for you to check.

Ref:

Civil defense siren - Wikipedia, the free encyclopedia

This one you should find very interesting ;)

http://www.mycivildefense.org/

Live feeds and everything.

[Clough]

So, the steady tone around here is probably a thunderstorm warning. Have been getting those a lot, lately.

[Clough]

Oops! The electricity just went out! :eek:

I'm getting off here!

[ebaines]

Oops! The electricity just went out! :eek:

I'm getting off of here!

Hey Clough - hope all is well! Here in the Chicago 'burbs our local alert warning siren went off last night for tornado warning - it was the steady tone, just as described in the Wikipedia article that Wondergirl posted. No tornados were actually reported in the area though.

[Clough]

Hi, ebaines!

There was at least one tornado sited around here as well as a lot of tornadic(?) activity.

Thanks!