* WHAT...Heavy snow expected. Visibility one quarter mile or less at times. Total snow accumulations 7 to 15 inches. * WHERE...Northern Susitna Valley, including the Parks Highway corridor through Broad Pass. * WHEN...From 1 PM Thursday to 2 PM AKDT Friday. * IMPACTS...Travel could be very difficult, with low visibility and rapidly accumulating snow along the Parks Highway. * ADDITIONAL DETAILS...Light snow will fall overnight tonight through Thursday morning, with 3 to 6 inches accumulation. Snowfall intensity will then increase during the afternoon hours. The heaviest snow will fall Thursday night through Friday morning. Snow could then mix with or change to rain Friday afternoon as temperatures warm above freezing. A Winter Storm Warning for snow means severe winter weather conditions will make travel very hazardous. If you must travel, keep an extra flashlight, food and water in your vehicle in case of an emergency. For the latest road conditions call 5 1 1 or visit 511.alaska.gov.