All of our medium and short range models indicate a storm system will move into Maryland by Friday afternoon and linger into Friday night. As arctic air settles across the state this week a storm will develop along the boundary of very cold air to the north and "milder" air to the south producing enough lift to create snow and rain across the region.
Below is the GFS (Global Forecast model) around Friday 1pm. The rain snow line is situated just south of Baltimore city with sleet over Washington DC. This model has been consistent in the rain snow being just south of Baltimore. Cold air aloft will be dragged down to the surface allowing for the entire column of air to be flooded with COLD. This means snow will be dominate with some sleet from time to time.
This is a look at the EUROPEAN model which has trended further south bringing the rain snow line over southern Maryland. Taken verbatim the heaviest snow would arrive during the Friday evening commute and 100% of the storm would be all snow. This would be a 3-5" amount if this model verified today!
The Canadian Model
This model shows a snowy start to the storm Friday morning however, a change over to rain and sleet would be expected Friday afternoon. This would produce a couple of inches before the change over with higher amounts over PA
I like this storm and I feel this has the most potential to bring snows across the state. That being said our models have lead us down this slippery slope before creating busted forecasts. I think the consistency in the modeling coupled with the cold dense air in place will allow for snow for everyone before a wintry mix will develop. The question then becomes does the wintry mix line setup over Baltimore city or Washington DC? That is a question we need to determine over the next couple of days!