After yet another balmy February day featuring the metro area’s fifth record high in the past six days, Minnesotans were switching back to their heavy winter coats to prepare for a major snowstorm expected to move in Thursday and last well into Friday.

Late Wednesday, a blizzard watch was in effect for those days for much of southwestern Minnesota, including Pipestone, Fairmont and Mankato. A slightly less dire winter storm watch covered a broad swath of south-central and southeastern Minnesota, including Willmar, St. Cloud, the Twin Cities, Rochester and Red Wing and moving northeast into western Wisconsin. The National Weather Service in Chanhassen said the watches could be upgraded to warnings overnight.

The heaviest snowfall — up to 18 inches — is possible southwest of the metro, including in Fairmont and Mankato, the Weather Service said. The Twin Cities will get anywhere from 4 to 12 inches, according to various forecasters.

As it often does, the Weather Service also had a caution — the area where heavy snow is forecast may narrow by early Thursday as forecast models evolve. The bands in which specific inches of snow are expected are narrow on the Weather Service’s forecast graphics, and any shifts in them could result in different amounts.

Precipitation will begin Thursday as rain, and turn to heavy snow by Thursday evening, forecasters said. It’s expected to snow heavily right into Friday night. Metro area commuters can expect some slow going both in the morning and afternoon commutes, and outstate travel may be dangerous or impossible as winds pick up and reduce visibility.

The storm will come on the heels of some very rare February warmth. Wednesday brought the sixth day in a row of record highs in the Twin Cities, where the temperature got up to 58, breaking a record of 57 from 1930. In St. Cloud, Wednesday’s high of 55 tied the 1961 record for that date, and in Eau Claire, Wis., a high of 57 tied a 1930 record.