MINNEAPOLIS (WCCO) – Heavy fog settled Thursday morning over southern Minnesota, reducing visibility to well below a mile, including in the Twin Cities metro.

The National Weather Service has issued a dense fog advisory for all of southern and central Minnesota, and it’s expected to last until the early afternoon hours.

Before sunrise, visibility in the Twin Cities was down to a 1/8 of a mile. Weather officials say fog this thick rarely happens in the metro, usually about once a year.

Motorists are advised to make sure their headlights are on and drive slow, as the fog may mask slick spots on wet roads.

The dense fog comes as Minnesota’s heavy snowpack continues to melt amid spring temperatures. Early Thursday morning, the mercury was above 40 degrees. However, temperatures are expected to fall throughout the day.

As the temperatures steadily drop, a low pressure system will move into Minnesota, bringing rain to the southern and central parts of the state. Later in the evening, the rain could turn to snow as temperatures drop below freezing.

Meteorologist Matt Brickman says that if snow does fall on the Twin Cities, it won’t likely stick to the wet ground. However, all the meltwater puddles on the sidewalks and streets will re-freeze.

Meanwhile, in northwestern Minnesota, the situation will be different, as a blizzard warning is in effect until early Friday morning.

The low pressure system is expected to bring light snow and strong winds, up to 60 mph to the area. Drivers are advised to stay home, as blowing snow and even whiteout conditions will make travel dangerous.

Indeed, a no travel advisory was issued Thursday morning in extreme northwestern Minnesota, west of Thief River Falls.

Looking ahead to next week, there’s some good news (for those who like spring weather). Brickman says there’s a chance Minnesota could see temperatures hit 50 degrees next Friday.