Winter storm taking aim on Pana

A winter storm is targeting Central Illinois and the Pana area, starting Tuesday night. Models are generally in agreement that a low-pressure system will bring accumulating snow to the Pana area. However, there are some issues with the forecast, including expected temperatures near or above freezing, which may limit the amount of snow accumulation, and the potential for heavier snowfall bands that could overcome less-than-favorable surface temperatures. With all of these factors considered, we are looking at a starting point of 4-6 inches of snow. Let’s discuss the timing and when we can expect the snow.

The snow is expected to start Tuesday night, according to the GFS and NAM models, around 9 PM. Note that there could be a brief period of rain/wintry mix at the onset of the event. Snow rates are expected to increase overnight Tuesday and early Wednesday morning, with large, wet flakes expected. Snowfall rates could exceed 1.5 inches per hour early Wednesday. The snow is expected to start to taper off around noon, with the snow completely out of the area by 3 PM Wednesday.

So how can the forecast fail? The forecast can fail in several ways. My biggest concern is with the surface temperatures being near freezing. Although we may get 4-6 inches of snowfall, we may only end up with 2-4 inches of total accumulation on the ground. My second concern is the chance of rain mixing in, which could significantly reduce the snowfall amount and leave us with 1-2 inches of snow accumulation on the ground. It’s also important to keep an eye on the track of the low-pressure system. If the track shifts further south, it would significantly lower the snowfall totals for the Pana area

So how can this forecast overperform? One thing I have been monitoring in forecast models is that they tend to be a bit too warm with surface temperatures. This could mean they are underrepresenting the total snowfall amounts and we could end up with more. Another thing to watch for are the heavy mesoscale showbands that are likely to set up. These bands tend to persist over an area and drop heavy snow over a period of time, resulting in much more snowfall than expected

Key Takeaways:

A winter storm is expected to hit Central Illinois and the Pana area starting Tuesday night, with models generally in agreement about the low-pressure system bringing accumulating snow.

• There are issues with the forecast, including expected temperatures near or above freezing, which may limit the amount of snow accumulation, and the potential for heavier snowfall bands.

• The snow is expected to start around 9 PM Tuesday night, with the possibility of a brief period of rain/wintry mix at the onset of the event. Snow rates are expected to increase overnight Tuesday and early Wednesday morning, with large, wet flakes expected.

• The forecast can fail in several ways, including surface temperatures being near freezing which may limit the amount of snow accumulation, and the chance of rain mixing in which could significantly reduce the snowfall amount.

• The forecast could also overperform, with models potentially being too warm with surface temperatures and underrepresenting the total snowfall amounts, and the potential for heavy mesoscale snow bands to persist over an area and drop more snow than expected.