It'll be a memorable Thursday and Friday in parts of Minnesota.

The first significant snow of the season is arriving in northwestern and north-central Minnesota. The snow spreads into northeastern and central Minnesota Thursday evening, then expands southward.

The Twin Cities metro area could see rain turn to a rain-snow mix overnight, then to all snow in parts of the metro area for a while Friday morning. The snow or rain-snow mix would taper off later in the day.

Big picture

The National Oceanic and Atmospheric Administration's North American Mesoscale forecast model shows the potential rain/snow pattern Thursday through Friday evening:

NOAA NAM simulated radar from Thursday through Friday evening, via tropicaltidbits

Green areas in the simulated radar loop indicate rain, blue areas are snow.

Temperatures in the lowest few thousand feet in the atmosphere will be marginal for snow at times, so blue areas could be a rain-snow mix at times especially near the Twin Cities metro area.

How much snow?

The heaviest snow is expected to fall over northern Minnesota, where some spots could see over 6 inches:

Parts of southern Minnesota, and areas just to the west of the metro area could see several inches of snow.

The snow and strong winds arrive earliest in northwestern Minnesota:

NWS Grand Forks, ND

Notice the 6- to 10-inch snow potential in the Roseau, Minn., area from this storm.

NOAA's North American Mesoscale forecast model shows the heaviest snow bands:

NOAA NAM snow totalsi from Thursday through Friday evening, via tropicaltidbits

You can see that the NAM has some 4 inches-plus snow for the far western edge of the seven-county Twin Cities metro area, with much lighter amounts for the east metro.

Snow forecasts aren't easy when dealing with a rain to mix to snow event.

Here are the snow projections for Minneapolis-St. Paul International Airport, using NOAA's various forecast models:

NOAA model snowfall meteogram for MSP via Iowa State University

There's a range among the forecast models from less than 1 inch to about 5 inches.

NOAA's Weather Prediction Center shows the odds of four or more inches of snow from this storm at various spots in Minnesota and Wisconsin:

NOAA/NWS/WPC probability of 4 or more inches of snow

We'll be watching for later model runs and observe the timing of the changeover from rain to mix to snow as this winter storm evolves.

Warnings and advisories

A winter storm warning is already in effect for heavy snow and blowing snow in northwestern Minnesota, and the warning runs to 1 a.m. Friday.

A winter storm warning starts at 3 p.m. Thursday and continues until 7 a.m. Friday in north-central and parts of northeastern Minnesota:

NWS Duluth

Here are details, from the NWS:

URGENT - WINTER WEATHER MESSAGE National Weather Service Duluth MN 1012 AM CDT Thu Oct 26 2017 MNZ011-012-270315- /O.UPG.KDLH.WW.Y.0021.171027T0000Z-171027T1700Z/ /O.EXA.KDLH.WS.W.0005.171026T2000Z-171027T1200Z/ North St. Louis-Northern Cook/Northern Lake- Including the cities of Ely and Isabella 1012 AM CDT Thu Oct 26 2017 ...WINTER STORM WARNING IN EFFECT FROM 3 PM THIS AFTERNOON TO 7 AM CDT FRIDAY... * WHAT...Heavy snow expected. Plan on difficult travel conditions. Total snow accumulations of 4 to 6 inches are expected. * WHERE...North St. Louis and Northern Cook/Northern Lake County. * WHEN...3 PM today to 7 AM Friday. * ADDITIONAL DETAILS...Be prepared for significant reductions in visibility at times. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Winter Storm Warning for snow means severe winter weather conditions are expected. If you must travel, keep an extra flashlight, food and water in your vehicle in case of an emergency. The latest road conditions for Minnesota can be obtained by calling 511 in state, or 1-800-542-0220. For Wisconsin, call 511 in state, or 1-866-511-9472

Much of the remainder of northern Minnesota is in a winter weather advisory from this afternoon into Friday morning.

Advisories cover much of central and southern Minnesota Thursday night into Friday.

A winter weather advisory includes Carver and Scott counties of the western Twin Cities metro area from 1 a.m. Friday to noon on Friday:

Here are the details:

National Weather Service Twin Cities/Chanhassen MN 1112 AM CDT Thu Oct 26 2017 MNZ055>059-064>069-270015- /O.CON.KMPX.WW.Y.0012.171027T0600Z-171027T1700Z/ Swift-Chippewa-Kandiyohi-Meeker-Wright-Yellow Medicine-Renville- McLeod-Sibley-Carver-Scott- Including the cities of Benson, Montevideo, Willmar, Litchfield, Monticello, Granite Falls, Olivia, Hutchinson, Gaylord, Chaska, and Shakopee 1112 AM CDT Thu Oct 26 2017 ...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 1 AM TO NOON CDT FRIDAY... * WHAT...Snow and blowing snow expected. Plan on slippery road conditions, including during the morning commute on Friday. In addition, significant reductions in visibility are expected. Tree branches could fall as well. Total snow accumulations of 2 to 4 inches are expected. * WHERE...Portions of central Minnesota, east central Minnesota and west central Minnesota. * WHEN...1 AM to noon Friday. * ADDITIONAL DETAILS...Winds gusting as high as 45 mph will cause widespread blowing and drifting snow. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Winter Weather Advisory for snow and blowing snow means periods of snow and blowing snow will cause primarily travel difficulties. Be prepared for snow covered roads and limited visibilities, and use caution while driving. The latest road conditions for the state you are calling from can be obtained by calling 5 1 1.

In addition to this blog, you can get winter storm updates on the Minnesota Public Radio Network, and on the MPR live weather blog.