As Spring begins and we look forward to warmer temperatures and longer days, we’ll be dealing with quite the opposite over the next 48 hours. Yet another powerful coastal storm is developing this morning and will bring more heavy snow, gusty winds, and ice to both the Mid-Atlantic and Northeast. While this will be another nor’easter / coastal system, it won’t be like the last three we dealt with this March. Instead it will come in two separate rounds as a series of low pressures develop along and off the Mid-Atlantic coastline.
The first round is currently underway, and will be the icy part of our storm. As we move through the day, a mixture of heavy sleet, freezing rain, snow and rain will move through the northern Mid-Atlantic cities like Washington DC, Baltimore and Philadelphia. This will create a mess for the afternoon and evening commutes with up to a quarter inch of ice and sleet falling in some places. As wind gusts increase and ice accumulates on some power lines and trees, more damage like we saw with the last two storm systems will be possible. This means a large area of scattered to widespread power outages as well as trees and branches falling.
Power outages and damaged trees will be the greatest threat to the corridor extending from extreme eastern West Virginia and southern Pennsylvania to the northern suburbs of Washington DC, and then through Baltimore and up into Philadelphia, New York City and southern New England. These are the areas that will see the worst of our storm system with heavy snow, icing, and gusty winds.
As this first piece of our storm slows down, a second, more powerful piece will develop offshore. Colder air will be in place from the first system allowing northern air to infiltrate the entire region down to the coastline, and force most mixed precipitation to changeover to all snow. Our newly formed low pressure will then track in a northeasterly fashion, and spread moderate to heavy snow all the way from central Virginia to central Pennsylvania and out east into southern New England.
The most difficult aspect of this forecast right now is how close the low come to the coast and how far back the precipitation field extends. Computer model guidance has been waffling back and fourth on where to place the cutoff and heaviest snow, but at this point it seems like a safe bet to say the I-95 corridor from Baltimore to New York City will be in the best (or worst depending on how you feel about snow) spot. Beginning Wednesday morning and lasting through the evening, bands of heavy snow and gusty winds will move through this region, while also branching out to the north and west through much of south-central Pennsylvania and southern New England.
Our latest forecast calls for a very widespread area of 6+ inches of snowfall extending from around Pittsburgh through Philadelphia and into southern New England. This region will see localized totals of up to a foot of heavy wet snow. There will also be a small swath with over a foot of snow will be possible, extending from the suburbs just north of Philadelphia to central Long Island to Rhode Island. With winds increasing during the day on Wednesday and the worst of the snow falling around that time as well, conditions will be hazardous for traveling.
Our storm wraps up Wednesday night and Thursday before sunrise, with temperatures rebounding nicely during the day. The good news is the snow that does fall shouldn’t stick around for too long. What we really have to focus on at this point though before we reach the end of our storm, is where the placement of heaviest snow and our tight cutoff set up. Again, for now we believe that the I-95 corridor and suburbs to the north and west will be in the sweet spot for snow, but shifts are still very much possible. If new data from the NAM and ECMWF gain more support today, we will likely shift this swath slightly to the south and east, taking a good portion of southern New England out of the brunt of the storm, and seeing areas like the Delmarva moving into the thick of things. Another update this evening will have that covered.