Accumulations of light and powdery snow will occur tonight into Christmas Day and night across south central and southeast Wisconsin, as a series of low pressure systems move through the region.
There will be two rounds of snow across the area. These rounds of snow will be driven by two troughs of low pressure, in the middle levels of the atmosphere, moving southeast through the region. See the water vapor satellite imagery below. The dashed lines indicate the position of these troughs of low pressure, as of Tuesday morning:
The first round of snow will be tonight into early Christmas Day, as the first trough of low pressure moves through the region. Light snow will spread west to east across the area this evening, lasting through the overnight hours. There will be a period of moderate snow during the late evening and overnight hours. The snow will end from west to east by the middle morning hours on Christmas Day. Snow accumulations of 2 to 3 inches are expected with this first round of snow.
The second round of snow will spread west to east across the area during the afternoon Chirstmas Day, lingering into the early evening hours, before ending later Wednesday night. This is in response to the second trough of low pressure moving through the region. Mainly light snow is expected with this second round, and will bring another 0.5 to 1.5 inches of accumulation across the area, with the highest amounts toward Darlington, Monroe and Janesville.
See the graphic below for the timing with the first round of snow across the area tonight:
Below is a map of the expected snow totals for the forecast area, and the entire state, tonight into Christmas Day and night.
Snowfall expected for south central and southeast Wisconsin tonight into Christmas Day and night:
Snowfall expected for all of Wisconsin:
Below are radar loops from our local radar, as well as regional views to the west and east of the region.
Click one for a larger version:
Regional Radar - West View
Regional Radar -
Those with travel plans tonight, Christmas Day and night should prepare for the snow. This snow will be the light and powdery variety. The snow will lead to snow covered and slippery roads. Slow down and allow for extra time to reach travel destinations.
NWS Milwaukee/Sullivan, WI