It was a chilly day across Philly with an official high at the airport of 35(at 1:49pm) after a seasonable low of 24 this morning. We had sunshine giving way to clouds in the afternoon in advance of our next storm system.
We have a Winter Storm Warning in effect from 11pm Tuesday until 9am Wednesday; now this is not really for a huge snow accumulation, but rather a mixture of snow, sleet, and freezing rain leading to ice(and hence leads to travel difficulties).
With the cloud cover overnight lows will just be hovering around 30. It's not so much the surface temperature that's important, but rather the layers aloft that will warm up prior to the surface(warm air is less dense than cold air so cold air sinks). This means as precipitation begins around Midnight it will be snow; around the early morning hours milder air just a few thousand feet above the surface and will cause frozen precipitation to melt, but refreeze before it reaches the surface. This will lead to periods of sleet and freezing rain(leading to some accumulating ice) by the morning commute. It won't be until the mid-to-late morning once temperatures at the surface finally climb above freezing and ensure everything changes to plain old rain.....BUT not before we receive a couple of inches of wet snow, sleet, and 0.10" of ice. The evening commute shall be fine, but overnight Wednesday into Thursday temperatures will drop to the middle 20s so untreated roads and surfaces shall refreeze.
This will lead to Thursday being cold with highs just around freezing, but we get closer to 40 come Friday with plenty of sunshine. This weekend another low pressure area will ride up the coast as well as a short wave along the Great Lakes. This will create the potential for snow or rain, but as of right now it's way too early to tell as let's get through this storm first(take one storm at a time!).
You can check out the rest of the seven day(any time) at www.scottderekwx.com/forecast.html.