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Cold And Snow Looms into Mid-December

Updated: Dec 2, 2022

In this week’s update, I thought I’d do something a little different. Rather than focusing mainly on the next 7 days, let’s take a look at what is coming our way as we head into the second and possibly third weeks of December. The bottom line is, atmospheric conditions are pointing towards a colder than normal look to December. There will likely be warmups in between, so it won’t be cold the entire time. As we’ve seen in November, temperatures can swing up and down, even though the average of the entire month ends up either warmer or colder than normal. Mid-December is looking colder than normal overall and potentially snowy as well. As cold air advances over the relatively warm Great Lakes, lake effect snow will be likely, and if we get a Low Pressure system or two to move through, which we should, widespread accumulating snow across the state would become likely.

First of all, over the next 7 days, things are looking relatively mild, or at least near normal with highs in the 30s to lower-40s. The exception is one warm spot in this forecast, when temperatures will likely climb into the 50s late Tuesday into early Wednesday. This warmth will come with rainy and windy conditions as wind gusts between 35 and 45 MPH will be possible. Thursday through Saturday should be relatively quiet before another chance for rain Sunday.

Now this is where things could get interesting heading into the first full week of December. More specifically, the December 5th-7th timeframe. Remember cold and snow are favored heading into mid-December? Well, this could be the start of the intrusion of much colder air. We are already seeing some ensemble guidance picking up on a Low Pressure system tracking through the Great Lakes region during this timeframe. Cold air will be advancing south from Canada at this time, which would support snow. At this point, the specifics cannot be known, but I do think somewhere in the Midwest/Great Lakes can see accumulating snow from this and potentially a winter storm. The map below shows the warm air to the south and the cold air coming in from the north, which results in a clash of the airmasses and Low Pressure forms and tracks along this temperature gradient, potentially leading to an impactful snow event.

After this potential snow event, regardless of where snow does or does not occur, an arctic air-mass should advance south into the U.S., resulting in very cold air. The more snow there is on the ground, the colder it can get locally. With all this cold air moving over the warm Great Lakes, lake effect snow would become likely. So the bottom line is the December 5th-10th timeframe is favored to be cold and snowy given what we are seeing right now.

The weather happens across the globe, so we must look at the wind patterns globally to figure out how things will interact and find out what may happen down the road. As illustrated in the figure below, High Pressure ridging is forecast to occur over Alaska and Greenland, which will force the cold air over the arctic to become displaced to the south. This is known as splitting and displacing the tropospheric polar vortex, which results in the cold air being forced into Asia and the United States next week. In addition, there is a southeastern U.S. ridge, which sets up a clash of airmasses across the northern U.S., setting up a temperature gradient. This is where Low Pressure typically forms and tracks, so this is why we favor the cold and snow risk between December 5th and 10th. It is important to note that this is a large synoptic overview of the northern hemisphere showing a favorable pattern for this cold and snowy forecast. The exact track of Low Pressure and more specific details have to be ironed out as we get closer, since there are many other smaller mesoscale features that play a role in the more detailed outcome of any given event, but the background state of the troposphere as a whole supports what we have discussed here.

Next Monday, we will have another chance to see how things have evolved and discuss the latest trends and expectations. If all goes according to plan, someone will have a winter storm on their hands. We don’t know if it will bullseye mid-MI for sure or not this far out, but it is certainly possible and something we want to watch closely before next week arrives.

November Snowfall & Temperature Statistics

It has been a snowy month of November so far. Even though there have been several 70 degree days along with plenty of warm days in general this month, it doesn’t take much snow to put us above normal. Interestingly, the normal snowfall in Mount Pleasant during November is 2.8 inches and with multiple days of snow occurring during the week of the 14th, we measured 8.6 inches of snow. This is more than 3 times the normal amount of snow. Because the snow occurred in an on and off fashion throughout the week, we never had 8 inches of snow on the ground at one time due to melting, settling, and blowing, but the measurements of new accumulation reveal we did indeed see this much. We know this is true because new snow accumulation is measured as soon as the snow stops each time so that an accurate measurement can be taken prior to melting and settling, so the total snow on the ground was never as high as the new snow accumulation. Furthermore, lake effect hit the west side of the state significantly, where up to 30 inches of snow fell near Grand Rapids. Compared to a normal amount of 4.4 inches during November, this means some areas on the west side of the state have seen more than 600% of the normal snowfall this month. The bottom line is snow has been much above average this month even though we have had spring and summer-like days mixed in as well. Temperatures are actually running about 2 degrees above normal for the month, so it certainly has not been a cold month as a whole. It goes to show it doesn’t take a colder than normal month to have a lot of snow; just need enough cold air when it matters in order to produce accumulating snow as Low Pressure sets up or lake effect becomes favorable to produce the wintry white stuff.

Mt. Pleasant Almanac for This Week:

Almanac Information is a way to look at normal and record high and low temperatures for this time of year. The normal temperatures are based on the 30-year average high and low for that date between 1991 and 2020. For example, if you take the high temperature for every November 28th between 1991 and 2020 and calculate the average of all 30 values, the result would be 40. Therefore, the normal high for today is 40°. Record high and low temperature data goes back to 1895. Sunrise and sunset data is also provided. All information is valid for Mount Pleasant.

November 28th

Normal High/Low: 40°/27°

Record High: 65° 1990

Record Low: 2° 1955

Sunrise: 7:49AM

Sunset: 5:05PM

November 29th

Normal High/Low: 40°/27°

Record High: 61° 1960

Record Low: 3° 1976

Sunrise: 7:50AM

Sunset: 5:04PM

November 30th

Normal High/Low: 40°/27°

Record High: 64° 1998

Record Low: 2° 1976

Sunrise: 7:51AM

Sunset: 5:04PM

December 1st

Normal High/Low: 39°/26°

Record High: 65° 1970

Record Low: 4° 1936

Sunrise: 7:53AM

Sunset: 5:04PM

December 2nd

Normal High/Low: 39°/26°

Record High: 62° 1970

Record Low: 0° 1966

Sunrise: 7:54AM

Sunset: 5:03PM

December 3rd

Normal High/Low: 38°/26°

Record High: 64° 1982

Record Low: -6° 1940

Sunrise: 7:55AM

Sunset: 5:03PM

December 4th

Normal High/Low: 38°/26°

Record High: 63° 1982

Record Low: 1° 1966

Sunrise: 7:56AM

Sunset: 5:03PM

Mid-Mitten Weather View’s Mission is to serve people by providing timely information to help keep you safe and make decisions based on the weather. We are passionate about educating both our forecasters and our followers about how weather forecasting works and how we can be best prepared when impactful weather threatens. Our team consists of both CMU alumni degreed meteorologists and current student forecasters from the University. For daily updates, we welcome you to check out our Facebook Page! We look forward to catching you back here next week for another weekly 7-Day forecast update.

-Weather Forecast by CMU Student Forecaster Isaac Cleland

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