This is a strong indication that a tornado is likely. There is often a strange quiet during, or immediately after a thunderstorm, this also can be an indicator of a possible tornado. The funnel cloud may be obscured by heavy rains, or it may not appear to reach the ground. Debris being pulled upwards is a sure sign a tornado is present. Most tornadoes do occur during the months from March to June and from 3 to 9 PM, However tornadoes have been recorded in every month and at all times of the day and night.
Tornadoes only occur in the central and southern states.
Opening windows allows violent winds to enter the building. Do not waste time with windows if a tornado warning is issued, seek shelter immediately. The low pressure a tornado creates will cause buildings to explode. Scientific evidence shows this is not true. In fact violent winds and debris slamming into buildings cause the most damage.