Information on County Tornado Sirens
A little information on how tornado siren's in Marshall County are activated and why:
Marshall County Communications Center (911) is in charge of activating the city of Marshalltown and those cities in Marshall County with remote radio controlled tornado warning sirens. They are only activated in two cases (1) for testing every Tuesday and (2) for an actual tornado warning. The tornado warning can be two things (1) a tornado spotted by radar from the National Weather Service in Johnston or other areas working with the Johnston (DM) office and (2) storm spotters spotting a tornado or funnel cloud in Marshall County and reporting it to the Marshall County Communications Center (this is sometimes confirmed then by law enforcement or other storm spotters that are sent near the area to locate the cloud formation and confirm rotation).
There has been some confusion by citizens in recent events because of two reasons (1) some other counties in the state of Iowa have chosen to also sound sirens when there are winds predicted to be over 70 mph (example is Polk County), Marshall County does NOT sound sirens for high winds, only tornado warnings, and (2) for the past couple of years there has been a change by the National Weather Service on how tornado warnings are given to an area. In the past, when a tornado warning went out, it went out for the entire county it was predicted to be heading into, but now with radars being better at spotting and tracking storms, there are polygons of prediction for tornado and thunderstorm warnings. The warning sirens will ONLY go off in the areas that the National Weather Service polygon is encompassing (the area it is over on the mapping).
The new apps for phones are a great way of getting information at your fingertips, but remember, these are general county warnings and will not be as specific as the tornado sirens or the actual radar can show and tell you.
Tornado sirens are for OUTDOOR warning ONLY! These are not intended for indoor warning and not intended for citizens to hear inside their homes. NOAA Weather Radios are the best way to get warnings indoors and get complete information.
Another question is about how does one know if the storm is passed and is there an "all clear" sounding of the tornado sirens. There is not an "All Clear" sounded. The best way to know if it is okay to be out of the storm shelter area you are in, is to monitor the weather radio information on where the storm is located and also to wait about 20 minutes after a storm warning is set for your area. Radar is a great way to know if the storms have passed or not.
If you have any questions, please feel free to call or contact my office by e-mail or on this page. Thank you for your questions and concerns.