JimE

12 miles nnw of center city Philadelphia, 32.5F air temp, moderate rain, turning the thin coating of snow into a sloppy slushy mess, difficult to see if rain is freezing on untreated surfaces because the untreated surfaces are covered with snow.

12 miles NNW of center city Philadelphia: air temp dropped to 32.4, on the ground is a coating, maybe 1/4 inch, can still see lots of green in the lawn, now mixing with sleet (pinging on the windows). Neighbor tried to get car up his driveway hill, couldn't. Snow coating often does that at this temperature.

Your temps probably are different from mine. My air temp is at 33 but the surface temp is lower. The snow, though very light, is beginning to accumulate on parts of the street and driveway. So the surface isn't warm enough to melt it. If it changes to rain before the surface warms there will be ice.

Tricky situation, though. Rain washes away the salt, but if the ground remains cold enough, the rain freezes on the surface. So it's a question of when, where, how much to put down. Some places are predicting small drops in temperature to 31, 32, 33 overnight which could make some roads treacherous tomorrow morning. These types of storms (snow to mix to rain to mix to rain to snow) are a challenge not only for forecasters but for road crews.

12 miles NNW of center city Philadelphia: very light snow has started, can barely see it, nothing yet on ground, 33F, no wind.