If I'm headed someplace that is 4 hours NE on back roads, and I'm driving NE but come to a T intersection, I can turn right or left and know to turn the opposite direction to go back to my NE direction. But not all roads are straight. By having a compass I'll know whether that long curved road I drive on turned me back to NE, or if I need to make a turn at the next intersection. It's a great way to enjoy a ride and find new roads and scenery.
The Weather Channel will give me a forecast for an area, but that's not what I'm looking for. I like to monitor the temperature. More for curiosity, but also because if the roads are wet, and it near 0ºC, the temperature is and indicator for the possibility of black ice. Black ice doesn't have anything to do with your highway speed because it's stationary.
The temperature can change 1ºC for every linear foot. The Weather Channel measures temperature at 4ft above ground level. That means if the temperature, according to the Weather Channel, is 4ºC than it could be 0ºC at ground level which has the possibility for black ice.
If I had a thermometer on the bike that wasn't exposed to wind or engine heat, and it was 3 ft from the ground, I could estimate at a 3ºC reading that the road water could freeze and adjust my driving accordingly. Of course, there's ground temperature, wind, sun/shade and surface material that all factor in as well so I'm not looking for certainty with regards to black ice, but if I left work with a 3ºC reading and half way home it changed to 5ºC I could be reasonably sure the roads won't have ice.
