Winter Storm Forecast Update: Snow North, Rain South

Posted at 12:01 PM, Dec 18, 2012
and last updated 2012-12-18 18:14:50-05

GRAND RAPIDS, Mich — New information this morning has revealed more about the forecast track of the winter storm poised to impact West Michigan, but has not allowed for a confident snowfall forecast just yet.

Computer forecast models have now come into better agreement that the center of low pressure will take a path from around Chicago through lower Michigan and over Lake Huron Thursday and Friday.  This means that enough warm air will invade West Michigan during the day Thursday to keep the initial burst of precipitation mostly snow.

Only areas around and north of US-10 are likely to see mostly snow, resulting in overall higher snow totals.  Elsewhere, the transition from rain to snow will take place Thursday afternoon and evening, with snow and blowing snow continuing into early Friday.

The best initial guess of snow amounts is approximately two to four inches, on average, around West Michigan.  If there are significantly higher totals, they will occur well north of Grand Rapids (where precipitation stays mainly snow); in lake-effect snow bands that develop briefly Friday morning; and possibly in areas southeast of Grand Rapids (where some computer models develop a burst of heavier snow overnight Thursday night).

Regardless of the final snow amounts, we can be confident that Friday morning commuters will see a significant disruption, if only because of wet pavement that will freeze Thursday night.  In addition, blowing and drifting of snow will make it somewhat more difficult to remove from the roads.  I expect that schools that have their last day before winter break scheduled Friday may cancel classes more quickly than in a normal situation, in part due to the impending holidays, and because few schools have used any snow days yet.

The image above shows the areas that have been placed under Winter Storm Watches for this storm; it clearly shows that the heaviest snow is likely to carve a swath to our west and, eventually, north of us.  Parts of northern and perhaps central lower Michigan may be added to the watch later on Tuesday.

Click here for meteorologist Kevin Craig’s description of earlier storm forecasts, and click here for the updated 7 Day Forecast on the main Weather page.