The latest data shows just two small changes to the winter storm forecast. With the storm start time getting closer the winter storm watch has been re-defined for most of Lower Michigan.
A winter storm watch is usually issued when a storm system is one to two days from starting. This long lead time is used to help you get ready if you have to make travel or work changes. Eventually as the storm gets closer, the winter storm watch either turns to a winter storm warning or a winter weather advisory.
Latest revision (3:26 p.m. Tuesday) of the winter storm watch to mostly winter weather advisories in purple. There still is a waiting game with the winter storm watch in blue for the Thumb, Oakland county, Macomb County and the northeast shoreline.NOAA
Due to the late morning model data being one inch lighter on snow, most of the winter storm watch has been turned into a winter weather advisory. There is also the thought that we are in the heart of winter in Michigan. The NWS uses six or more inches as the criteria for a solid winter storm warning.
The map above shows how the large winter storm watch area earlier today has been fine-tuned to mostly winter weather advisories. A winter storm watch still exists for the Thumb and northeast shoreline until the next round of data shows which way to go on the watch. There should be some lake enhancement of the snow totals in the Thumb and northeast shoreline, possibly putting those areas over the six inch winter storm warning criteria.
So it’s a winter weather advisory for 4 inches to 6 inches of snow for most of the southern two-thirds of Lower Michigan. The far southeast corner, including Ann Arbor, Detroit and Monroe, is expected to get some freezing rain. This will cut the measurable snow to 2 inches to four inches in far southeast Michigan.
Here’s is the latest total snowfall forecast from the model that should be the most accurate at this timeframe. I’ve actually just received this new model data and it’s back up an inch in spots. The six inch swath is more narrow, but still quite a swath from Kalamazoo to Lansing to Flint to the Thumb.
Total snow forecast from the North American Model (NAM) through Thursday afternoon.NOAA
Here are a few notes.
Grand Rapids seems to be in the transition zone from six inches southeast to four inches in the city to two inches northwest of Grand Rapids. The snow amounts also go down in the far southeast part of Michigan due to some freezing rain. The ice accumulation is expected to be around one-tenth of an inch near Monroe, the south side of Detroit and southeast of Ann Arbor.
Ann Arbor will also be in the transition zone from six inches north and west of Ann Arbor to less than four inches southeast of Ann Arbor.
The eastern Thumb will likely have widespread six to seven inch snowfall amounts.
This isn’t a mega-snowstorm for Michigan. It’s the type of snowstorm we usually have about two to three times in an average winter in southern Michigan.
The snow is still expected to start early Wednesday afternoon, be at its heaviest Wednesday night and end early Thursday morning.
Continue to watch for more updates here.
