Each time SkyScan detects a lightning stroke, it emits an audible warning tone (if this feature has been turned on by the user; see Section 5 in Basic Operation) and lights the Range indicator column. The full column stays lit for approximately 3 seconds. The single indicator corresponding to the range of detected stroke will then blink for approximately 25 seconds. This feature allows you to quickly see the distance to the last, closest detected stroke without waiting for SkyScan to detect a new stroke. VERY IMPORTANT! Because the average stroke of lightning is 6 miles long, and because thunderstorms can move at speeds of up to 25 mph or more, you are in immediate danger any time there is detected lightning activity within 8-10 miles of your location. You must also remember that SkyScan does not predict where the next lightning stroke might occur. Thunderstorms are unpredictable and should be considered extremely dangerous. BE AWARE THAT STORMS CAN FORM DIRECTLY OVER YOUR LOCATION, OFFERING LITTLE OR NO ADVANCE WARNING, EVEN WHEN USING A SKYSCAN.