Northeast Snow Tonight Unusually Dangerous

I want travelers in the Northeast to understand the danger of tonight's snow event, because just looking at the current accumulation map (see Headlines at right for updated maps) it doesn't look like it's going to be that big of a deal - 1 to 3 inches north and east of Philly.

But due to the cold temperatures, a number of things will happen with this storm that haven't with previous storms this season:

1. It will be too cold to melt on roadways. Here in Central PA, if it's not actively snowing outside, snow melts quickly on the roads, because it's typically in the upper 20's or lower 30's when it snows. Today, however, high temperatures are struggling to get into the teens, and lows could be in the single digits tonight. This will make the road conditions more treacherous, not even counting #2 below.

2. It will be so very cold, road & driveway treatment may not work. Roads could be slicker, and you could have to apply more treatment to your driveways and sidewalks that you normally would. This will apply after the storm as well.

3. The snow will accumulate faster than normal due to unusually high snow ratios. I am told by the meteorologists on the Operations floor today that snow ratios could be three times higher than normal because of the extremely cold temperatures in the lower atmosphere. This means that if you got 1 inch last time, you'll get 2-3 this time, even though the storm's strength is the same.

4. Winds will causing blowing snow, especially near the end of the storm and afterwards. Again, more problems on roads and sidewalks than usual, especially combined with the cold temperatures above in #1.

So please don't underestimate this snowfall as a "minor clipper" system, and stay safe out there tonight.