Warning sirens will be activated if a tornado has been sighted near Norwalk. A steady 3-minute tone will indicate a tornado warning and that you should immediately seek shelter in your basement or an interior room in your house. The Weather Bureau uses the term tornado watch to mean conditions are such that a tornado is possible. The sirens will not be sounded for a watch but will be for a tornado warning (a funnel cloud has been sighted in the area either by radar or an observer). The sirens are tested the first Saturday of the month at 1:00 p.m.