* WHAT...Heavy snow. Additional snow accumulations between 3 and 7 inches for a storm total of 7 to 16 inches, locally up to 18 possible along the southern spine of the Greens. * WHERE...All of northern New York and Vermont * WHEN...Until 1 AM EST Tuesday. * IMPACTS...Roads, and especially bridges and overpasses, will likely become slick and hazardous. Travel could be very difficult to impossible. The hazardous conditions will impact the morning and evening commutes. * ADDITIONAL DETAILS...Wind chills in the St. Lawrence Valley will remain about 15 below much of the night and early this morning. With the potential for locally 18 inches, like in southern Vermont, ensure adequate ventilation when heating homes or using generators to avoid carbon monoxide risks.