Special Weather Statement issued February 11 at 4:06AM EST by NWS

…Patchy Dense Fog and Black Ice Expected Through Mid Morning… Patchy dense freezing fog and black ice have been observed across the area overnight. Visibilities locally under one half mile along with patchy slick spots on area roads will persist through mid morning. Conditions may change quickly due to ice and fog, therefore motorists should exercise caution this morning.

Source: National Weather Service Alerts for Vermont