Saturday November 21st 2015 Great Lakes Potentially Significant Winter Storm

What was originally looking as though it could be a mixed rain/snow and/or freezing rain event this weekend is now looking more and more like an all-snow event. As such, a significant amount of snow - specifically, 3 inches or more of accumulation - now appears as though it may coat the ground throughout most of lower Michigan this weekend, save for south of I-69 and east of I-75.

The above images represent surface level pressure, precipitation and surface temperature as forecasted by the latest GFS run for Friday evening into Sunday morning. A significant surface low is forecast to develop and deepen throughout the day on Saturday, and it should bring adequate moisture to the table to drop some significant precipitation, just as temperatures begin to plummet below the freezing level to the magical range of 25-28°F - the temperature range at which snowfall is usually heaviest. This is a "Panhandle Hook" style system, though it also has shades of a "Colorado Low" - both of these types of storms are historically the types that bring the most snow to our area, as they build in from the south and pick up moisture from the Gulf of Mexico.

Another concern with this system, should this forecast verify, is just how strong the winds will get. 

Above is depicted winds around 925mb as predicted by the GFS for Saturday morning through early Sunday. Winds at these levels may reach 50 knots over Lake Huron. This could mean that winds could whip up to more than 35mph at the surface, which is the criteria set for a Blizzard Warning. It's too early to tell if this storm will be strong enough to cause such winds, but any snow that fell Saturday would likely be blown about into significant drifts should it even be half as potent as what this run is predicting.

Winter weather is a bit easier to forecast than severe thunderstorms, but at this point we're still in a "wait and see" situation. Minute differences in temperature can mean everything when it comes to storm mode, and it's still a bit too early to tell exactly what we're going to see this weekend. With that in mind, this is looking to me as though it will be the first major winter storm of the season, and a fairly good one at that.