A Winter Weather Advisory remains in effect for the entire WTVO forecast area. Going forecast still looks on track as far as totals go - still looking at 3"-6". A few localized higher amounts still remain possible. There were a couple of things I wanted to point out that might play a factor into snowfall later this evening. First, the graphic on the left is a forecast sounding from Davenport, IA from this morning. The red line represents the temperature profile throughout the atmosphere and the green line is the dew point. What I want you to notice is how the temperature and dew point line start together but then grow further apart the higher up in the atmosphere. This basically means that our low levels are dry and any precipitation that falls through that layer will likely evaporate before reaching the ground. As of 1pm we still have a fairly dry dew point at the surface so even though there are radar returns popping up over Illinois and eastern Iowa, the only snow reaching the ground is in north-central and central Iowa. This may actually delay the onset of snowfall as we head later into the afternoon/evening - which in turn may lower totals in some locations. However, we should start to see the atmosphere saturate a little more throughout the day. I still anticipate the snow to begin around the supper time hour.
Heavy snow will likely begin to evolve over parts of southern Minnesota and northern Iowa mid-afternoon as an upper level low and warm air advection begin to push east into the upper Midwest. We're already starting to see totals reaching 4" across parts of north-central Iowa. Totals greater than 6" still appear likely northwest of Rockford, probably closer to the Mississippi River.
We will continue to monitor the evolution of our system and keep you updated as we go through this afternoon.
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