* WHAT...Heavy snow expected. Total snow accumulations 12 to 18 inches. The highest amounts are expected along the Lake Ontario shore and southeast of Lake Ontario due to lake enhancement. * WHERE...Monroe, Wayne, Northern Cayuga, Oswego, Jefferson, and Lewis Counties. * WHEN...From 7 AM this morning to 7 AM EST Tuesday. * IMPACTS...Travel will be very difficult. The hazardous conditions will impact the Monday morning and evening commutes. * ADDITIONAL DETAILS...The bulk of the heavy snow is expected this afternoon through tonight, with moderate snow continuing along the southern and southeastern shores of Lake Ontario through Monday night, especially from Wayne to Oswego counties .