It’s the second day of Winter Weather Awareness Week in Wisconsin, and our second daily topic is about the process meteorologists use to predict winter precipitation, especially snow.
Even after a day or two, the output of the various snow storage computer models can vary widely. This is where you need to be careful what you see on social media. A screenshot of the output of a computer model for snow is often posted on some hype sites. Usually they post a week or more in advance and find the model with the best snow performance.
Problem is, even the most prestigious models regularly issue maps that show a foot or more of snow for even a week, but snow of this magnitude is extremely rare, even in western Wisconsin. However, the computer models show that they happen 10 to 20 times each winter and we know that is not true.
Meteorologists therefore differentiate between model output and forecast. A forecast takes into account all of these model outputs, identifies outliers, and creates a series of probable snow sums. In addition, the computer model output for snow is just one parameter that is taken into account in it.
Better forecasting actually starts with estimating how much rain would fall if it did fall as rain. Forecasters start analyzing the general course of the storm a few days before the expected snowfall to determine which area is most likely to fall and how heavy it might be. When you get closer, this area is adjusted accordingly.
Once it’s outside a day or two we can start looking for specific amounts of rainfall. As mentioned earlier, meteorologists start with liquid equivalent prediction. Then they analyze the temperature and humidity in the atmosphere not only on the surface, but also from the ground up into the cloud cover. In addition, it helps to determine the strength of the buoyancy movement with snow rates and flake type.
Finally, these parameters are also considered to determine the rain to snow ratio, and the liquid precipitation forecast as such is multiplied to obtain the snow forecast.
Now for today’s forecast: Temperatures rose in the lower to mid 40s mainly southwest of Eau Claire with the mid to upper 30s in the northeast. While these temperatures were close to average, it never really felt that warm when you factor in gusts of wind that hit nearly 50 km / h. The wind won’t be as strong overnight, but a small breeze will stay and be strong enough to create wind chills that are five to ten degrees colder than the air temperature.
West Wisconsin saw some drizzle today, but it didn’t even add up to 1/100 “. Tomorrow there should be at least a few hours of sunshine, which should be enough to get you into your lower to mid 40s.
Colder air will return tomorrow night when a cold front passes, but there’s little chance of thunderstorms or the occasional light snow. Those little chances are there until Thursday, which will stay breezy, but the wind won’t be quite as strong.
The coldest temperatures this week come in with teenage lows on Thursday night / Friday morning, but temperatures are warming up a bit again to kick off the weekend. Roller coaster temperatures will drop again from Sunday to early next week, and there will be more disorganized and slim chances that it will keep snowing despite those temperature fluctuations.
Matt was promoted to Chief Meteorologist in 2019. He started as our Saturday night meteorologist in September 2014 before being promoted to evening meteorologist in 2016. Born and raised in Sheboygan, WI, Matt loves everything about this great state, including experiencing all four seasons and deer hunting. He enjoys predicting all kinds of weather and cheers all of Wisconsin’s sports teams in the process!