Prolonged mega-moisture storm will have 3 zones in Michigan: Ice storm, heavy snow and possibly severe t-storms

We have a long-duration precipitation event heading toward the Great Lakes. Get ready for significant amounts of precipitation. Here are some of the basic details on this storm.

I would call this a meaningful or even a memorable storm for some of us, as it will likely have a zone of very heavy snow, an ice storm zone and maybe a line of severe thunderstorms.

Two pieces of strong upper-level energy are going to merge right over Michigan. When this happens, precipitation can last two days. This will be the case with the coming storm.

The precipitation starts Saturday night and early Sunday morning, then continues, often times heavy, through Monday night. The storm should be over around sunrise Tuesday.

Here is the surface weather forecast from 1 a.m. Sunday to 7 a.m. Tuesday. Yes, the purple color will likely end up as a stripe of heavy freezing rain and sleet, resulting in an ice storm.

Surface weather forecast from 8 p.m. Saturday, March 14 to 1 a.m. Tuesday, March 17.NOAA

Here are the zones of weather.

For the southern half of Lower Michigan, you stay in the warm sector of the storm until Sunday night. Occasional showers and thunderstorms will occur Sunday and Sunday night, then snow showers will fall Monday and Monday night. There could be a line of severe thunderstorms as the strong cold front moves through Sunday night or Monday morning. The Storm Prediction Center (SPC) already has an area targeted for possibly severe thunderstorms. The graphic below gives us a great idea of where the rain-to-freezing rain line may set up, from around Ludington to Alpena. All areas south of that line could warm into the 60s Sunday, and have thunderstorms. It’s the kind of set-up that can produce tornadoes.

Severe thunderstorm chances from 8 a.m. Sunday to 8 a.m. Monday. The black diagonal hatching denotes significant severe weather possible.NOAA

Unfortunately, there looks to be a significant ice storm zone, where one-half inch of ice to as much as one-and-a-half inches of ice could accumulate. This amount of ice accumulation will cause widespread power outages.

Here’s the total freezing rain accumulation forecast as of this Friday afternoon. The zone could still shift north 15 to 25 miles. If that happens, the southern edge, to just rain, shifts north, and the northern edge with its heavy ice, would also shift north. So still monitor MLive.com/weather for updates and changes. These changes could still be very significant at any location.

I’m showing you the most reliable model for placement and precipitation type. It might be an inch too heavy on ice accumulation. Let’s hope so. This storm also has the ability to do as this forecast shows, accumulating over one inch of freezing rain.

Total freezing rain accumulation forecast through Monday morning.NOAA

This means a zone from the Traverse City area to Charlevoix to Grayling and Gaylord and into northeast Lower Michigan could have a devastating ice storm with over one inch of ice accumulation. The models may be combining sleet with freezing rain, which certainly would be better than all freezing rain. This is the zone that will have to be watched.

In the far northern part of Lower Michigan and the Upper Peninsula, the precipitation should be all snow, and very heavy. The National Weather Service in Marquette is starting to talk about a “record snow.” I don’t have a number of inches for that record snow, but it’s heavy.

Here’s the total snow forecast. Ignore the exact numbers at exact locations for now. If some rain and sleet and freezing rain mix in on the southern edge of the snow(likely), those areas will get lesser snows.

Total snow forecast through Monday morning. There would still be three to six inches left to fall over northern Michigan Monday and Monday night.NOAA

The entire Upper Peninsula should get between 20 inches and 30 inches of snow. Far northern Lower Michigan should get 10 inches to 20 inches of snow.

It may be hard for Traverse City to get 11 inches of snow, just based on the idea that Sunday and Sunday night should be freezing rain, sleet and rain.

How do you respond to this storm system? Travel on Saturday, before the precipitation gets started. The southern half of Lower Michigan will even be okay to travel Sunday, except for the chance of a line of severe thunderstorms. Temperatures will soar into the 60s Sunday from Saginaw southward.

Sunday, Sunday night, Monday and Monday night will not be safe to travel in northern Lower Michigan and the Upper Peninsula. Southern Lower Michigan will get into the snow showers by Monday, and roads could get slick.

Tuesday will have improving road conditions, as the precipitation should end around sunrise.

It will take until Wednesday afternoon before northern Michigan warms above freezing, getting rid of any ice on the back roads.

This is a complex storm system that is still just developing. Do expect some shift possibly in the zones of weather I just wrote about. I don’t expect a shift south, but there could be a slight shift north.

Stay updated at MLive.com/weather.

Here’s a short video explainer of the coming storm.