Odds that a snowstorm will take shape in portions of the Mid Atlantic this upcoming week continue to grow, with Thursday being the likely day some will see impactful snows. Computer forecast guidance has been flipping on the notion of the storm curving up the northeast coast; if it were to do that, the axis of heaviest snow would shift from between southern Virginia and the Philadelphia metro area to the area between Philadelphia and Boston.
While some runs have brought the storm up the coast to impact New England, most haven’t. Because of that, there is growing confidence that this storm will impact portions of Virginia, Maryland, Delaware, New Jersey, and Pennsylvania more so than other states. However, because the storm is still in the 5-6 day timeframe, there is still a good deal of uncertainty among the models and the meteorologists that use them to create their forecasts.
The GFS and ECMWF are among many computer models meteorologists use to assist in weather forecasting. While meteorologists have many tools at their disposal to create weather forecasts, two primary global forecast models they do use are the ECMWF from Europe and the GFS from the United States. While the models share a lot of the same initial data, they differ with how they digest that data and compute possible outcomes. One is better than the other in some scenarios, while the opposite is true in others. No model is “right” all the time. Beyond the ECMWF and GFS models, there are numerous other models from other countries, other academic institutions, and private industry that are also considered when making a forecast.
For now, both the ECMWF and GFS have been waffling over weather this storm will hook up the coast into New England. But even if it doesn’t, the area that saw significant snow earlier this week –coastal Virginia to southern New Jersey, should see a repeat of plowable snow.
The latest model runs seem to have more of a southeast track with the low, meaning highest snow accumulations would be over Delmarva and southeast New Jersey, and back towards the I-95 corridor.
The National Weather Service says their guidance is suggesting a 30-50% probability for more than 4 inches of snow north and west of the I-95 corridor and a 50-70% probability for more than 4 inches of snow across southern New Jersey, the eastern shores of Maryland and Delaware in the 48 hour period from 7 am Wednesday through 7 am Friday; a 20-30% probability for more than 8 inches of snow north and west of the I-95 corridor and a 40-50% probability for more than 8 inches of snow across southern New Jersey, the eastern shores of Maryland and Delaware in the 48 hour period from 7 am Wednesday through 7 am Friday. The same guidance also says there’s a 20-30% probability for more than a foot of snow in this region in the 48 hour period from 7 am Wednesday through 7 am Friday.
Regardless of the final storm track, a Canadian high pressure system will build back into the east from the west for Friday, bringing cold but dry air back to the Northeast and Mid Atlantic. How much snow people will be digging out from them, though, remains to be seen. The National Weather Service may begin to issue Winter Storm Watches for the storm as soon as Monday evening.
