Welcome to Winter. It seems like just last week we were talking about the potential for some snow showers, and now Mother Nature is back with more! This time, it’s in the form of ice…
This weekend, Central/Western VA and portions of western NC will be “wedged in” with cold air. High pressure to our north and low pressure to our south will create a setup called cold air damming. When this happens, cold air gets trapped or wedged up against the Appalachian mountains and can’t escape, just like water in a dam. This is a fairly common thing for VA and NC.
In cold air damming, the cold air is generally very shallow and close to the surface. This sets up the potential for freezing rain. To get freezing rain, you have to have cold air below 32°F at the surface and some warm air aloft. As the precipitation falls through the sky, it melts and falls as rain all the way down to the surface. Since the cold air is shallow, the water droplets don’t have time to re-freeze into sleet (ice pellets). As a result, they fall as rain and hit the ground as liquid precipitation. However, since the ground is below 32°F everything that falls freezes on contact, creating an icy glaze!
This type of setup is what is going to occur this weekend across central and western VA. The map below and to the right is from Matt DiNardo’s FB page. I’ve linked it because I feel like it is the best representation of the impacts I’ve seen thus far.
East of Richmond including Hampton Roads:
- Most of the precip falls as rain, but some sleet and light freezing rain is possible
- Generally no major travel issues
Richmond Metro along I-95 :
- I believe that the dividing line between a major ice accumulations will be the Richmond metro area. Having said that, a glaze up to a half of an inch of ice is possible and this could certainly bring down some power lines in area.
- Travel could become difficult at times, especially on untreated roads and sidewalks.
West of Richmond Metro including the University of VA, JMU, Longwood, VT and Radford:
- The potential exists in these areas for a major ice storm that causes significant travel disruptions and power outages.
- Over a half of an inch of ice is possible in the Blue Ridge mountains, with slightly lesser amounts as you go down in elevation.
- Some snow and sleet accumulation up to an inch is also possible across western VA, with higher amounts possible especially in the higher elevations N of Roanoke.
Ice storms are not fun… They cause power outages and can make travel impossible. I would strongly advise against any long distance travel on Sunday especially across western portions of VA.
As always, things can change. We, as weather forecasters are not as good as we think we are. We make mistakes and forecasting any type of weather, and especially winter weather is not easy…. There are many many factors that you have to take into account. Numbers and impacts are subject to change we get closer to Sunday.