It came on quick late day but quick hitting, bursts of snow roamed central Indiana late Friday at times reducing visibility under these snow showers and light accumulation. These are selective and will be diminishing in coverage and intensity through the overnight.
The bursts of snow are driven by the “heating” of the day and the presence of a “stacked” low in the Midwest. The churn overhead and the warming during the day encourages clouds to build and snow showers, bursts and squalls to develop. Very much like a warm, summer day and a passing shower or thunderstorm drifts by, the ingredients are the same but just occurring in the the winter months.
Low pressures are stacked vertically in the atmosphere from the surface up to jet stream levels. Left behind by the main branch of the jet stream, the slow moving lows drift in unison slowly east for the next few days. The churn overhead aids in agitating the atmosphere and aided by the heating of the day encourages these snow showers to come to life. The upper-low will depart come Monday and that is when the threat of snow will diminish completely.
After sunset, these taper down and off but are expected again Saturday and Sunday. If you are under one or two or three through Sunday, local accumulation of a half-inch to one and half-inches are possible. Roads that get a coating are most likely to be coated under the most intense snowfall and later in the evening and afternoon sunset.
Snow showers will increase to nearly 30% coverage by Saturday afternoon and evening before tapering off again at night. Sunday, the process starts all over again on Sunday.