Things have come into focus a bit more since yesterday's forecast, and we now have a better idea of what will likely happen. As I advertised yesterday, this will not a big snowstorm nor will it be a big ice storm. This is the first time this season that we will have to worry about a threat of ice, but it is not a big threat here in Southern MD. For a quick summary, skip down to "The Bottom Line" paragraph.
We are actually going to be looking at three different areas of low pressure that will all work to give the Mid-Atlantic snow/sleet/freezing rain/rain.
The first area of low pressure will move in overnight. It's a small system that is normally referred to as a clipper. Instead of merging with the main storm system, it will run out ahead of it, and start to have snow break out tonight, after sundown and likely around midnight. It is this small system that will give us the majority of our snowfall as we will not be looking at ice from it. What ever falls overnight and tomorrow morning will stick right away as ground temperatures are in the lower teens and actual air temps will be between 12-18. Thus, roads could be snow covered by the morning rush. Dry air might be an issue once precipitation starts showing up on Radar, so it will take time to actually get snow down to the ground.
Once that small "clipper" system moves out, our main storm system will take over, or the second low pressure. It is completely possible there is a time late tomorrow morning or early tomorrow afternoon where nothing is falling as one system moves out and the other takes over. Nevertheless, temperatures will still be cold enough late tomorrow morning to support snow, so anything that falls will be likely be white. As the system starts to move north, it will bring in some warmer air. It will warm the upper atmosphere first, before the "surface" where we live. This means that after lunchtime Monday, we will start to mix with sleet and eventually freezing rain. It's during this time that we could see some minor ice accumulation. As the surface starts to warm, we should switch over to all rain. This change over will gradually happen from southeast to northwest, so areas northwest of I95 will take longer to switch over, but will eventually do so too. Rain is likely throughout Monday evening into Tuesday afternoon. Some flooding could be possible as we could see up to 1" of rain.
The third, and last, low pressure system we might have to deal with is another small clipper system early Wednesday morning. Right now, it looks rather weak and temperatures look a tad too warm for much more than rain. Nevertheless, it is something to watch, and if it were to bring snow, it would be light with minor amounts. Not expecting too much from that.
The National Weather Service has issued Winter Storm Warnings (pink areas) and Winter Weather Advisories (purple areas) for a large swath of the Mid-Atlantic. Those under the Warnings will see higher snow and ice accumulation totals. It will take longer for these locations to switch from snow to ice, and then from ice to rain. Power Outages are possible and travel is not advised. For the Advisory areas, there will be lesser amounts of snow and ice, but there will still be travel difficulties as well as the outside chance of power outages.
For those who have school or work on Monday, I fully expect those places to be closed. Snow covered roads by the morning, along with a transition to ice, will make commuting difficult. It is still too early to make a call on Tuesday, but delays/closings will be dependent on how late the snow/ice stick around on Monday. I'll have school odds for Tuesday up tomorrow afternoon.
The Bottom Line is that snow will move into the region overnight tonight which will switch over to icy mix after lunchtime, and will be all rain by Monday evening. This will not be a big snow or ice storm, but the snow and ice on Monday will be disruptive. Roads could be snow covered as early as sunrise Monday, so travel is not advised. Any schools or business that are scheduled to be open on Monday will likely be closed. It is still too early to say what will be opened on Tuesday. I have pretty good confidence in this forecast. If temperatures are cooler than expected and dry air isn't an issue, snow/ice totals could be higher, if they are an issue, totals could lower. Nevertheless, I like where my forecast stands. I will have coverage all day tomorrow. Stay with JB Weather for the latest on Southern Maryland weather.