The Weather Channel will likely name a fast-developing, and fast-moving coastal low to impact the Mid Atlantic tomorrow, Winter Storm Iago.
The storm will spread a swath of snow across the Central Appalachians, West Virginia, Virginia, Maryland and Delaware, as it moves out of the Tennessee Valley and offshore late tomorrow night.
Based on the current model storm track, the center of the action is expected to stay south of the Washington-Baltimore region. However, with sub-freezing air in place near the surface, and abundant moisture pulled into the storm, accumulating snow is likely to reach as far north as Baltimore.
The first figure, based on a computer model forecast for tomorrow evening, shows the surface low (1007 mb) over the North Carolina-South Carolina coastal border. Colors represent precipitation amounts. D.C. - Baltimore is on the far northern fringe, with 1/4" to 1/2" precipitation totals. The precipitation bullseye - painted red, to the tune of 2" - is poised over the Central Appalachians, hundreds of miles to our southwest.
|Surface Weather Forecast, Thursday evening (Unisys Corp)|
Below is another computer model forecast of snow amounts for tomorrow-tomorrow night:
|Forecast Snow Amounts for Thursday-Friday (Weatherbell Analytics)|
Finally, the NWS in Sterling has now issued a swath of Winter Storm Watches, including D.C., counties to the immediate south and north. The city of Baltimore and Baltimore County are NOT included at this time:
|Winter Storm Watch for Thursday (NWS)|
|10 PM - Forecast Snow Totals for Thursday(NWS)|
Of great interest, tomorrow we will be watching the radar evolution of this system very closely. A narrow band of heavy snow, with snow rates up to 2" per hour, is expected to set up somewhere across Central VA. Depending on the exact track of the storm...that snowband could shift north, as there has been a tendency in the models for the storm to track closer to D.C.-Baltimore.