Everything is lined up for deep snow in the southeastern half of Lower Michigan. In fact, the highest snow area continues to expand slightly to the north and west.
Two climatic conditions will help to really accumulate snow. We expect a period of three to six hours tonight, when large fluffy flakes fall. Light, fluffy flakes can add up more easily than small, heavy wet flakes.
The second climatic condition that is now apparent is a perfect direction of the flow of the wind towards the humidity of Lake Huron. This is not a common situation, it can happen once every one or two years. See the wind flow forecast below. The wind is blowing straight from Lake Huron. Although western Michigan is known for lake-effect snow, this time it is the eastern side of Lower Michigan that receives the most snow due to a Great Lake.
The wind flow forecast at 3 am on Tuesday, February 16, is blowing across Lake Huron and Lower Michigan.
This morning, it looked like a bunch of six and seven inch amounts in southeastern Lower Michigan. The upper end looked like isolated quantities of 23 centimeters. Now I would say there will be an abundance of snow totals of seven and eight inches, with some isolated amounts of 10 inches.
Here is the latest preview of the best model in this situation, called High Resolution Fast Update.
Total snow forecast of what must be one of the best models.
A big reason the model above is the best is that it can accurately predict the snow-to-liquid ratio of a given snow. In this case, we have what I call a “cold snow storm”. Generally, when it gets too cold, the air doesn’t have enough moisture for heavy snow. But remember, this time the air will be continuously fed by the moisture that evaporates from Lake Huron. An average ratio of snow to liquid is 10 inches of snow to an inch of water. This storm will have 15 inches of snow per inch of water.
The Lansing area and the Jackson area have been added to the Winter Storm Warning. This is a sign that the snow of more than 15 centimeters is expanding to the north and west.
So call 20 to 25 inches of total snow in the Ann Arbor area, Detroit area and now across the Thumb. Flint, Lansing, Jackson and Kalamazoo are expected to have between 15 and 20 centimeters of snow by the end of Tuesday’s midday storm. Saginaw and Bay City should expect 15 to 18 inches of snow. The Grand Rapids area is still in the 10 to 15 cm range. Muskegon is probably in the three to five inch range.
I hesitate to call it heavy snow, because the snow will be very soft and light. I think it’s better to call it deep snow.
Another climatic condition that can make driving dangerous is blown snow. The fluffy snow blows easily. Below is the forecast for surface gusts for Tuesday at 6am.
Forecast of gust of wind at 6:00 am on Tuesday, February 16, 2021
The yellow and orange areas will have gusts of more than 30 mph, producing a moderate to severe drift. The Torregrossa Drift Index calculates for 55 in Oakland County from 7 am to 8 am on Tuesday. A value of 55 in my drift index is in the category I call severe drift, although it is at the bottom end of severe drift.
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