Several inches of lake-effect snow are forecast to start piling up in Michigan’s Upper Peninsula late on Wednesday, Nov. 11, and the Weather Prediction Center puts the chance of at least 4 inches in the Huron Mountains above 70% through early Saturday, Nov. 14. The estimate rose from a Nov. 10 call of better than 50% that ran only through Friday, Nov. 13.
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Forecasters Fracasso and Miller wrote the newer discussion, issued at 2:26 a.m. EST on Nov. 11 and valid from 7 a.m. EST that day to 7 a.m. EST on Saturday. Their language is plain for a probabilistic product: multi-banded snow on northerly winds will likely accumulate several inches across the Upper Peninsula, with surface temperatures below freezing, and lighter snow is expected over much of the rest of the peninsula and the northern Lower Peninsula.
From 50% to 70%: how the forecast moved
The first call came from the center’s heavy-snow discussion of Nov. 10, issued at 2:55 a.m. EST that Tuesday and valid through 7 a.m. EST Friday. Fracasso wrote that the probability of at least 4 inches of snow was above 50% over the Huron Mountains, and that multiple bands would likely drop several inches Thursday into early Friday, with snow continuing beyond that. A probability above 50% is a better-than-even bet, not a promise, and the discussion does not give an expected total.
A read of the Weather Prediction Center’s front page on Nov. 11 showed the successor product. Its window ran a day longer, to Saturday morning, and its probability for the same 4-inch threshold in the Huron Mountains was above 70%. The extension matters because lake-effect snow does not stop when a window closes; the bands the forecasters describe were expected to begin late Wednesday evening and continue into Saturday. The discussion adds that the heaviest accumulation is favored away from the warmer lakeshore.
Earlier discussions are kept in the center’s public archive, where each file name carries the issuance date and time.
The product is the center’s Probabilistic Heavy Snow and Icing Discussion, written at College Park, Maryland, and the Nov. 10 edition covered a window of three days ending at 7 a.m. EST Friday. Each edition names the forecasters who wrote it, which is why the same Fracasso signature appears on both versions, with Miller added on Nov. 11.
Cold air behind a Mid-Atlantic low
The Nov. 10 discussion lays out the setup. Upper-level troughing digs south from Ontario into the western Great Lakes, the Midwest and the Northeast behind an exiting Mid-Atlantic low, bringing colder air across the warm, open lake. Northerly flow over Lake Superior then organizes snow into bands that can stall over the same hills. The Huron Mountains, in the western Upper Peninsula, are inland from the shore and higher than it, which is why forecasters single them out.
The same Nov. 10 product also flagged other spots. Northerly flow over Lake Michigan could produce a band of rain or snow into northwestern Indiana on Thursday evening into early Friday, with a possible narrow strip of wet snow if rates are high enough. In the Adirondacks, Green Mountains and White Mountains, the chance of at least 4 inches was above 50% above about 3,500 feet, with minor impacts expected. The probability of significant ice anywhere in the continental United States was under 10 percent.
What lake-enhanced snow has looked like here before
The National Weather Service office in Marquette issues the actual advisories and warnings for the Upper Peninsula, and its own event pages show what a strong lake-enhanced setup can do. A Nov. 9-10, 2018 event brought snowfall rates of 2 to 3 inches per hour in squalls, whiteout conditions, sporadic power outages and gales of 40 to 45 knots that built waves of 14 to 18 feet on Lake Superior. That page does not mention the Huron Mountains by name, and nothing in the current discussions predicts an event of that size.
Temperature is the other piece of the Upper Peninsula forecast. The newer discussion expects surface temperatures below 32 degrees Fahrenheit there, so the precipitation should fall as snow, whereas the Lake Michigan band reaching northwestern Indiana in the Nov. 10 text was described as possibly rain or snow, turning to wet snow only where rates are high enough. A forecast of several inches in the Upper Peninsula and a coin-flip mix to the south shows how sharply the outcome depends on the air temperature at ground level.
For readers planning Thursday and Friday drives, the specific number to watch is the Marquette office’s local forecast and any advisory it issues, since a regional probability of at least 4 inches says nothing about which road gets the heaviest band. The open question in the Weather Prediction Center’s own text is duration: the Saturday-morning end of the window may not be the end of the snow.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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