Stop signs are a part of everyday traffic for drivers around the world. However, due to their smaller size, lack of lighting and the fact that they can become visually obscured from the road, stop signs have a tendency to be much less effective than traffic lights. To solve this problem, we developed an Android application: Stop Watcher, which is designed to alert a driver when they are approaching a stop sign using a Voice Notification System (VNS). We conducted a field test in a snowy environment. The test results demonstrate that the application can correctly detect all stop signs, even when some of them were obstructed by the snow.