Where snow could be measured in inches – or feet – in the East this weekend

A major snowstorm is expected to hit the Northeast this weekend. It is a complex and evolving setup that could target parts of the mid-Atlantic and New England. The storm could bring upward of a foot of snow in some spots, along with strong winds and travel disruptions affecting a stretch from D.C. to Boston.

The system could undergo a rapid intensification process called bombogenesis. That swift strengthening could lead to a greater impact than initially expected, especially if it happens closer to the coast.

With sufficient moisture in place, there is even a chance that a foot or more of snow could fall in eastern Connecticut, Rhode Island and southeastern Massachusetts. In fact, as of Friday afternoon, the European ensemble model – which takes into account a wide range of scenarios – depicts a 70 % chance of Cape Cod seeing 12 inches or more of snow.

That is why confidence in double-digit snowfall totals is greatest in southern New England. Greater uncertainty exists south of New York City in the mid-Atlantic.

In recent days, one model – the National Oceanic and Atmospheric Administration’s Global Forecast System – has been favoring high-end snow totals in the mid-Atlantic, including the D.C. to Baltimore to Philadelphia stretch. While it is an outlier and tends to have lower skill than other models, several other forecast systems were also trending toward a snowier scenario. A middle-of-the-road scenario, with a notable snowfall of 3 to 6 inches, appears more probable there.

Winter storm watches have been issued in eastern Pennsylvania, the northern half of the Delmarva Peninsula, New Jersey, the New York City area and southern New England.

Balancing all this information, it is looking like snow will probably grow late Sunday in the mid-Atlantic, with the storm’s impacts peaking in the Northeast on Sunday night and Monday.

The threat for heavy snow hinges on an eventual merger between systems that were located in California and Alberta as of early Friday. Like two busy highway on-ramps converging, once the systems sync up, congestion builds fast – and so does the storm.

What to expect in the Mid-Atlantic

For people living in the Mid-Atlantic, a mix of rain and snow early Sunday could turn to locally heavy snow later in the day or at night – especially closer to the coast.

Unlike other storms this winter, there will be little cold air in place ahead of this storm, which should cut down on how much snow sticks and accumulates – because it will be wet and heavy.

Some cities that may be affected: Richmond and Fredericksburg in Virginia; D.C.; Baltimore and Ocean City in Maryland; Wilmington and Dover in Delaware.

Storm timing: The most likely period for accumulating snow and strong winds is from late Sunday into Monday.

Snowfall amounts: There’s high chances for 1 to 3 inches, medium-to-high chances for 3 to 6 inches and medium chances for more than 6 inches in most places. The highest snowfall amounts will probably be found closer to the coast.

It’s important to remember that a low chance doesn’t mean no chance – and even a small nudge in the forecast track could cause snow forecasts to rise dramatically or fall.

Meanwhile, the American GFS model continues to simulate a broad 1 to 2 feet of snow in the Mid-Atlantic. But in our assessment, the model is likely to over-intensify the system too early in its life cycle. A deeper or stronger storm system over land would inhale more cold air from the north and pull in more moisture from the south, leading to a high-end snowfall event for the nation’s capital. We believe that is improbable.

To the west, a localized zone of higher-end totals of 6 to 12 inches is possible on the west slopes of the Alleghenies, as well as in the Panhandle of Maryland along Interstate 68 in Garrett and Allegheny counties. That’s where upslope flow, or the forcing of moisture up the mountains from the west, will lead to greater snowfall totals. Plus, the mountains have a higher elevation, meaning colder temperatures that allow for more accumulation of snow.

What to expect in the Northeast

In the Northeast, chances for accumulating snow will be highest close to the coast and lower farther inland. Inside of Interstate 95, and particularly along 495, is where the bull’s eye will be in southeast New England.

But a key caveat is that a small change in the storm’s track could lead to relatively substantial changes in the forecast.

For Philadelphia and New York City, the most likely scenario is for 3 to 6 inches. Hartford could see 5 to 10 – a wide range, indicative of how much uncertainty is present. Boston faces a similar forecast. In fact, Boston could walk a bit of a tightrope, with a quick ramping up of amounts to the south and east over Plymouth and Bristol counties, including Fall River, New Bedford, Plymouth and Taunton, as well as Barnstable County, including Hyannis.

With a quickly strengthening storm southeast of Long Island, ample cold air swirling into the low-pressure system will keep precipitation predominantly or entirely snow, even on Cape Cod. That’s why they’ll get the highest snowfall totals, especially since they’ll be closest to the storm and tap into its greatest moisture.

Where snow has been abundant and lacking this winter

This winter has been snowier than average for populated swaths of the Midwest, Great Lakes, Northeast and Southeast.

Around 36 percent of people living in the United States have experienced above-average snowfall this season to date – the highest in five years.

While a few sizable storms are now rolling across the West – especially California – much of the region is experiencing a severe snow drought, with little long-term relief on the horizon.

That’s especially the case across Colorado, Utah, Idaho and Oregon.

In Salt Lake City, there has been 2.5 inches of snow so far this winter, compared with an average of around 40 inches.

That’s less than D.C., Charlotte and even Myrtle Beach, South Carolina – and far less than some East Coast cities will probably see from Sunday into Monday.