Snow total forecast lowered
9:10 a.m. update: Last night, based on the model data, we indicated we thought totals would be near the lower end of the ranges we had forecast west of the Bay. Based on this morning's radar and model data, we've decided to lower the accumulation total forecast. I think it's likely we'll still see snow around D.C., inside the beltway, and to the east this afternoon as the coastal low develops and heads north, but my confidence diminishes as you head west of the beltway. This remains a wait and see situation. If the storm is able to deepen quickly enough, it might be able to push the precipitation further west so I would keep a very close on eye on radar and satellite into this afternoon. The time period where conditions look to be the worst is from about noon through 7 p.m.
8:20 a.m. update: We're mulling lowering accumulation totals from D.C. and to the west and I even have a new map worked up, but we want to look at a little more model data before making this official. Just as I was hitting the button to post the new map, the radar is hinting that the storm motion is shifting a bit more toward the north and NOAA's Storm Prediction Center says the low is developing on the west side of model guidance. More in a bit.
7 a.m. update: True to form, this difficult to predict storm is closing in on the metro region and the fine line between where there will be appreciable snow and very little snow remains difficult to pin down. Regional radar shows moderate to heavy snow blossoming over central and eastern North Carolina and spreading northeast toward southern Maryland. Lighter snow is starting to spread into some of our southern suburbs with light snow or flurries reach St. Mary's county in Md. and Stafford county in Va.
This activity will move north and northeast today but it looks like there's going to be a a very sharp western cutoff. Radar and model guidance suggest the District and suburbs to the west will be on the dividing line between getting accumulating snow and getting fringed with just light snow or flurries. As you head west of Fairfax and Montgomery county, odds of accumulating snow seem to be low. East of the District, the chances of accumulating snow increase quickly especially as you head toward counties adjacent to the Bay where totals have a good chance to be substantial.
Snow should become more widespread across the metro region between 9 and 11 a.m., but watch for the sharp dividing line between snow and no snow. While the storm may throw more precipitation further west as it moves north this afternoon and evening, where it gets going this morning will be a pretty good indication of who is likely to get a meaningful snowfall and who gets just a glancing blow.