(Portland, OR) -- An Ice Storm Warning is in effect for the Willamette Valley and parts of Southwest Washington. The National Weather Service has issued a warning from 10 o'clock this morning through 4 a.m. Wednesday. The Portland area could see up to one inch of snow and ice accumulations from two-tenths to half-an-inch. The Central and Southern Willamette Valley could get between two-tenths and four-tenths of an inch of ice. Temperatures are expected to warm above freezing on Wednesday.