Minor accumulations of snow across the Chicago area Friday morning may have been helped along by soot particles floating up from smokestacks.
About an inch of snow was reported in Lockport about 5 a.m., and a “dusting” was reported near Aurora and Naperville, according to National Weather Service meteorologist Ben Deubelbeiss.
Smaller amounts were reported on the Far South Side and around the Indiana state line.
Very isol'd snow accums this AM likely related to particles from smokestack plumes aiding in snow crystal formation. More to come later.
— NWS Chicago (@NWSChicago) December 12, 2014
When radar images showed snow developing this morning, it seemed to be developing in isolated areas and not moving, which caused the weather service to speculate that a stationary source was causing it, Deubelbeiss said.
Conditions like those seen about 5 a.m., including low clouds, typically lead to drizzle, Deubelbeiss said.
However, particles from smokestacks may have drifted up into those low clouds, making it easier for ice crystals to form around them and leading to isolated accumulations of snow reported Friday morning.
Patchy fog is expected to linger in the area through Saturday night, with temperatures in the low to mid-40s expected Saturday, according to the weather service. Sunday’s high could reach 51, with a low in the mid-40s and a slight chance of rain overnight into Monday morning.