Metro Detroit weather: Wintry mix, accumulating snow on the way

Snow develops overnight

Paul Gross with the Dec. 17, 2021, weather forecast. (WDIV)

DETROIT – We had a beautiful Friday, as expected, with plenty of sunshine that is gradually being replaced by high clouds that will then thicken through the evening hours.

Then, snow and a wintry mix will develop, but probably not until around midnight, in our South Zone and spread northward through the overnight hours. This is what we’ll wake up to Saturday morning.

It’s nearly impossible in these types of weather situations to nail down exactly where the dividing line between the snow and the mix will be, but based on extensive review of the afternoon computer model data, as well as forecast upper air data, I think that transition will be somewhere between I-94 and 8 Mile Road.

North of there, most of what falls should be snow, with accumulations for most in the 1-2 inch range, and perhaps a small area that gets between 2 and 2.5 inches. That band would roughly be orientated from Jackson, to north of Ann Arbor, to Novi, to Bloomfield Hills, to Sterling Heights.

Farther south, everything is in play: snow, sleet, freezing rain and rain, which means that snow accumulation will be considerably less -- well, under an inch, and probably nothing near the state line.

Lows Friday night will be near freezing (adding to the complexity of the forecast), with highs Saturday reaching the mid-30s (1 to 2 degrees Celsius). This means it should be good packing snow for the kids. Let’s hope some of us get enough to go out and play in!

Friday evening’s sunset is at 5:03 p.m., and Saturday morning’s sunrise is at 7:57 a.m

Weekend forecast

Wind Saturday will start from the northeast and slowly become northwest by later in the day, at 5 to 10 mph.

The snow and wintry mix will taper off by Saturday afternoon, with just little spits of precipitation here and there -- nothing of any consequence. We’ll be mostly dry for our Saturday evening plans.

Clouds begin breaking up Saturday night, with lows in the mid-20s (-4 degrees Celsius).

Partly cloudy on Sunday, with highs in the low to mid-30s (0 to 1 degrees Celsius).

Christmas week

I don’t see any big storms on the horizon for us. That’s great news for travel around the Great Lakes. It appears a system passing just north of us will spread some snow across northern Michigan on Wednesday, with lake-effect snow developing behind the system.

After that, the long-range outlook for Christmas Eve gets interesting, as one model (the GFS) suggests some snow, while another model (the ECMWF) suggests that it’ll be rain instead. Stay tuned!

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About the Author:

Local 4 meteorologist Paul Gross was born in Detroit and has spent his entire life and career right here in southeast Michigan. Paul has researched, written and produced eight half-hour documentaries for WDIV, as well as many science, historical and environmental stories.