SWAW Side Note: Siren Activation and Thursday's Tornado Drills

Once again, it's Severe Weather Awareness Week here in Minnesota and Wisconsin, brought to you by the National Weather Service along with the Divisions of Homeland Security and Emergency Management. Each day a new topic of severe weather is covered, but we thought that we would bring you additional information on siren activation and tomorrow's tornado drills. We hope you find this information informative and helpful as we enter severe weather season and remember to stick with this blog for the very latest on severe weather throughout the season.


Siren Activation Information

Counties and cities own the sirens, and therefore decide how and when to activate them. The National Weather Service does not sound them.
There are many different policies regarding siren activation that are used by the various cities and counties. Some will activate sirens across the entire county for tornado warnings only.  Others will activate sirens countywide for tornado warnings and all severe thunderstorm warnings. Some will activate sirens across the entire county for tornado warnings and severe thunderstorms that have winds of at least 70 or 75 mph. Others will activate sirens only for portions of counties.  Local officials may also sound the sirens anytime they believe severe weather is a threat, even if there is no warning from the National Weather Service.
Sirens normally sound for about three minutes, and then go silent.  It is very rare to keep the sirens sounding for the entire warning, since that would cause the backup battery to run out, which would be critical in the event that power goes out.  Furthermore, the siren motor will fail much more quickly if the siren sounds continuously.  Some jurisdictions may repeat siren activation every few minutes.
There is no such thing as an "all-clear" for storms.
Please check with your local public safety officials for details on when warning sirens are sounded in your community.

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Tornado Watch/Warning Drills 
The National Weather Service, Wisconsin Emergency Management, the Minnesota Division of Homeland Security and Emergency Management, and other state, county and local agencies have come together to host Severe Weather Awareness Week activities. On Thursday, April 22nd, simulated tornado watches and warnings will be issued to test the statewide warning and communications systems. The schedule for April 22nd is as follows (all times CDT):

1:00 PM:  The National Weather Service will issue a simulated tornado watch for Minnesota and Wisconsin.

1:40 PM:  The National Weather Service will issue a simulated tornado warning for 9 counties of western Wisconsin (Barron, Chippewa, Dunn, Eau Claire, Pepin, Pierce, Polk, Rusk and St Croix). Note that most cities and counties will activate outdoor warning siren systems.

1:45 PM:  The National Weather Service will issue a simulated tornado warning for Minnesota counties (except those in the northwestern part of the state). Note that most cities and counties will activate outdoor warning siren systems.

2:00 PM: The National Weather Service will issue an "End of Test" message using the Severe Weather Statement product. It should be stated that outdoor warning sirens will not be sounded again for this all clear, nor will there be any warning tone on NOAA Weather Radio.

6:55 PM:  Another simulated tornado warning will be issued for 73 participating counties in Minnesota. Those counties not participating are: Aitkin, Carlton, Hubbard, Itasca, Kanabec, Kittson, Lincoln, Otter Tail, Pennington, Pipestone, Sibley, St. Louis, Watonwan and Wilkin. A graphic of the counties participating in the evening drill is available at http://www.severeweather.state.mn.us/Documents/Participating_Counties_Drill_Map_2010.pdf
The 6:55 PM warning will be issued by the six National Weather Service offices that serve Minnesota. It will be issued as a test of family preparedness in the home and for second shift workers.