Updated: Jan 16
It's easy to assume that when you are looking at a reflectivity mosaic like the one below that somehow the cities are the cause of this precipitation event. You can see in this snapshot from 0035Z on January 14th that there is reflectivity reported in and around the major cities of Pittsburgh, Cleveland, Charleston and Dayton. Could this be some sort of "heat island" effect during the winter? Hardly.
Despite what the radar looks like, cities don't somehow attract snow like you might see with respect to the formation of radiation-fog. In metropolitan areas, the heat island effect can greatly diminish or delay the onset of fog in urban areas. But that's not true for snowfall or any large-scale precipitation event for that matter. Instead, snowfall is somehow attracted to areas around NEXRAD sites! Notice the precipitation areas are nearby the NEXRAD sites for Pittsburgh, Cleveland, Wilmington and Charleston.
KPIT 140051Z 32011KT 5SM -SN BKN015 OVC020 M02/M05 A2994 RMK AO2
KCRW 140054Z 34008G14KT 4SM -SN BR BKN009 OVC021 M01/M02 A3000
KCLE 140051Z 35019G26KT 6SM -SN OVC016 M01/M05 A3004
KDAY 140046Z 34009KT 9SM -SN BKN023 BKN029 OVC034 M01/M04 A3012
But what about in the middle near Zanesville, Ohio where the area is void of any precipitation?