I drove out of my community and when I came up to the stop light and was about ready to turn north bound. I got a ka alert 1 to 2 bars. As I kept heading more northbound it slowly started to ramp up very slowly. At first I thought something was wrong with it slowly ramping like it was. Then I crossed a intersection it got to about 3 to 4 bars. I eventually came to a stop sign and kept going. Then finally it started to ramp all the way. Low and behond their was a leo behind a tree in a parking lot. clocking northbound traffic. When I had the chance I retraced the mileage it was 2.5 miles on pretty much flat terrain. It would have probably alerted further then that if their was more road going south bound. I was nothing short of shock at the distance pickup. I would have had way more then enough time to slow down if i was traveling down that road without turning onto it.