Update (4:07 p.m. Sunday, Jan 22):

The National Weather Service in Des Moines has extended the winter weather advisory for Ames. The advisory will now continue until noon Monday.

System wide snow predictions have also increased to 2-4 inches. Winds are also expected to be a little stronger, with sustained speeds of 20-30 mph and gusts of 35-40 mph. Visibility is expected to be less than one half mile in open areas, and whiteout conditions may exists from time to time on Monday morning.

The Ames forecast calls for rain before 9 p.m., a mix of snow and sleet between 9 p.m. and midnight and snow after midnight. Total accumulation of snow and sleet is forecast at 1-3 1/2 inches.

Update (11:39 a.m. Sunday, Jan. 22):

The National Weather Service in Des Moines has adjusted the timeline for Sunday’s wintery mix to chance over to snow, and increased snow accumulation totals.

Freezing drizzle is expected to continue throughout the afternoon and evening hours and chance to snow overnight.

Ice accumulation estimates remain at less than 1/10 of an inch, but system wide snow totals have increased to 1-3 inches.

With a forecast high of 35 Ames may avoid some of the freezing drizzle in the afternoon hours, but it is expected later in the evening. The chance to snow if forecast for around 9 p.m., with less than an inch of accumulation expected.

A wintry mix of precipitation headed toward Ames will trigger a winter weather advisory for Sunday into Monday morning.

The National Weather Service in Des Moines has set the advisory to go into effect at 9 a.m. Sunday and continue until 6 a.m. Monday.

Freezing rain is expected throughout the day Sunday before turning to snow and blowing snow Sunday night.

Patchy freezing drizzle will develop Sunday morning before becoming more widespread and mixing with sleet by mid morning. A gradual transition to snow is expected by Sunday evening.

The freezing rain is expected to be light and produce only a glazing of ice. Snow accumulations are expected around one inch. Ames is on the southern edge of the advisory, and the local forecast predicts less than 1/10 inch of ice and 1/2 inch of snow.

Winds will be an issue throughout the day. Southeast winds of 15-30 mph could cause drifting snow Sunday morning. Winds will shift to the northwest and increase to 20-30 mph Sunday night, causing more blowing and drifting snow. Visibility may be reduced to less than 1/2 mile in open areas.