* WHAT...Heavy snow expected. Total snow accumulations of 11 to 17 inches. Winds gusting as high as 35 mph.

* WHERE...Upper Koyukuk Valley.

* WHEN...From 3 PM this afternoon to 3 PM AKST Wednesday.

* IMPACTS...Travel could be very difficult to impossible. Areas of blowing snow could significantly reduce visibility. The cold wind chills as low as 20 below zero could cause frostbite on exposed skin in as little as 30 minutes.