A major winter storm is underway across the Mid-Atlantic region, nearly 2 feet of snow is forecast in the New York area and the Long Island. Deep snow cover is expected from Washington D.C. to Boston. The system will then blanket the Northeast United States and New England with huge snow over the next two days.
In our previous discussion regarding the developing dangerous winter weather tonight, we have talked about the strongly increasing potential for a monster Nor’easter to develop this Monday. A reason for this is the Arctic air mass blasts towards the East Coast with a frontal wave emerging from the west.
Today, a rapidly developing surface low is underway along the East Coast, already dumping heavy snow bands into the Mid-Atlantic Coast and New York.
Actually, this is the first major winter storm of 2021 for the Big Apple. It has already lead to strongly disturbed travels, shutting down coronavirus vaccination sites, and dumping a huge amount of snow over the city so far.
MAJOR SNOWSTORM UNDERWAY
Al the commercial flights at the International airport LaGuardia, New York have been canceled, including almost all flights from the John F. Kennedy and Newark airports as parts of New York have already received more than 10 inches of snow, making this Monday the snowiest over the last 5 years for the city. A couple of inches has also been reported from Washington D.C., Baltimore, and Philadelphia since Sunday.
More snow is forecast tonight. The city will likely wake up buried in snow on Tuesday morning!
Major coastal flooding is imminent. Increasing winds wind the strengthening Nor’Easter are worsening the threats as near-blizzard conditions have developed.
Winter Storm Warnings remain in effect into Tuesday morning
- Heavy Snow (14-20”) expected for Much of the Region
- 2-3”/hr snowfall rates this morning into the afternoon
- Near blizzard conditions expected especially closer to the coast
- Lower snowfall totals of 6-12” expected for SE CT and E Long Island
Strong Winds for the City/Coast
- 20-35 mph with gusts 40-55 mph today into this evening
Coastal Flood Warnings in effect for Long Island, NYC, and coastal NE NJ for today and tonight
- Minor to locally moderate coastal flooding with today’s AM/early PM high tides
- Widespread Moderate to locally Major coastal flood potential with Tonight’s high tide
Storm Warnings today into Tuesday for much of the coastal waters. Gale Warning for the Western LI Sound and NY Harbor today into Tuesday.
Coastal Flood Hazards and Impacts:
- Minor to moderate impacts daytime today
- The greatest threat of moderate inundation (2-2.5 ft above ground) along the south shores of Nassau/Queens
- Widespread Moderate to locally MAJOR coastal flood impacts Tonight
- The greatest threat of moderate to locally major (3 ft above ground) along the Long Island south shore and eastern bays
- Several waterfront road closures and potential property damage
Shoreline Hazards and Impacts:
- Breaking waves 5-10 ft oceanfront, 3-6 ft Long Island Sound shoreline, and Twin Forks
- Widespread ocean beach erosion/flooding Areas of dune erosion and isolated washovers along oceanfront Mon into Tue high tide cycles
- Flooding will likely start well before times of high tide tonight and continue well after.
- Minor to locally moderate flooding up riverine areas of Lower Hud and NE NJ likely tonight
- Additional minor to moderate flooding likely during Tue high tide cycles. Highest threat of moderate flooding for the Long Island south
shore bays Tue Am.
This is a typical and a textbook Nor’Easter setup, normally resulting in a huge dump of snow for the Mid-Atlantic Region. The low will travel northeastward along the coast on Tuesday and threaten the Northeast United States and New England with very heavy snowfall, blizzard conditions, and a huge snowpack.
HOW NOR’EASTER FORMS?
A Nor’easter system is a synoptic-scale extratropical low forming in the western North Atlantic Ocean. As we could assume from its name, the winds affecting the coastal areas are generally from the northeast direction. Such storms originate as a low-pressure area that forms within approximately 100 miles of the shores between North Carolina and Massachusetts.
These systems are usually accompanied by heavy rain or snow and can cause significant coastal flooding, coastal erosion, and hurricane-force winds. When heavy snowfall develops over the land, extreme blizzard conditions emerge. Nor’easters often rapidly strengthen on the converging air masses — an Arctic cold air mass from the north and the warmer air over the water.
Nor’easters are more severe in winter when the difference in temperature between these air masses is the greatest. They tend to develop the most intense between the months of November and March, although they can also develop during other, non-winter months. The east and northeast parts of the United States are generally impacted by these systems a few times each winter.
Generally speaking, the Nor’easter develops in response to the sharp contrast in the warm Gulf Stream ocean current coming up from the tropical Atlantic and the cold air masses coming down from Canada. In the upper atmosphere, the strong winds of the jet stream remove and replace rising air from the Atlantic more rapidly than the Atlantic air is replaced at lower levels; this and the Coriolis force help develop a strong cyclone.
Nor’Easters track northeast along the East Coast, normally from North Carolina to Long Island, then moves toward the area east of Cape Cod.
So this is exactly what has happened this past weekend, An intense Arctic blast spread into the Northeast United States and the East Coast, meeting with much warmer Atlantic. Today (Monday), their effect had lead to a formation of a rapidly developing surface depression which is expected to deepen its central pressure below 980 mbar through early Tuesday.
Now, a major Nor’Easter winter storm is imminent along the Mid-Atlantic and Northeast regions tonight through Tuesday. What the weather models are simulation is a very significant snow accumulation – locally, close to 2 feet of snow (50 cm) could blanket the areas from eastern Pennsylvania across the city of New York. Close to a foot of snow is forecast for the Boston area as well.
THE WORST ARRIVES TONIGHT
A major winter storm has now emerged near the Atlantic coast, while the central pressure continues deepening. This is rapidly worsening conditions across the Mid-Atlantic Region, including the cities of Philadelphia, New York, and Boston. Huge snow accumulations – locally close to 2 feet – are likely over the next day or so.
The Nor’Easter will gain strength and size tonight and mature on late Tuesday. Potentially pushing its central pressure close to 980 mbar while the core will be moving towards Nova Scotia. The attached map below shows how large the system is becoming, dominating the East Coast and the Northeast of the United States.
The system is surrounded by higher surface pressure. One blocking High is extending across the central parts of the country, while another two high-pressure systems are to the north and east. Therefore Nor’Easter is moving at a very slow forward speed, being trapped in the locked-in pattern.
The setup over the eastern portions of the United States is also becoming favorable for another cold outbreak towards the Southeast. The Nor’Easter will be drifting northeast on Tuesday with a strong cold blast into the Southeast United States and also Florida in its wake.
The attached temperature forecast for Tuesday reveals a big contrast between the tropical air mass coming up from the western Atlantic while the system is parked along the Atlantic Coast.
This is a textbook example of a fully developed Nor’ester as we discussed above. The interaction of the Arctic air mass coming from the north and the tropical air mass from the south, develop a major system.
The attached map below, provided by Windy.com with the ICON model, reveals a tremendous amount of snow is likely to accumulate tonight through Tuesday morning across eastern Pennsylvania, northern New Jersey, and southern New York states.
These areas are going to be blanket by 20-25 inches (2 feet) of snow in total on Tuesday. Travels will be challenging, and roads may be blocked with huge drifts of snow.
A lot of snow is also expected further northeast across New Hampshire and Maine as Nor’Easter makes progress towards Nova Scotia through Tuesday night into early Wednesday. Significant snow amounts are also expected along with the coastal areas.
Here is an additional map, provided by the Pivotal Weather NAM model. This chart hints at the greatest snowfall across eastern Pennsylvania, New Jersey, southern New York across Connecticut, and Massachusetts. Locally close 25 inches is possible by Wednesday morning.
WINTER STORM HEADS FOR NOVA SCOTIA ON WEDNESDAY
After the Nor’easter gains strength on Tuesday, its further progress will not be particularly fast towards the northeast. This means that snowfall will persist and maintain across many hours (12-18 hours in some areas), and lead to the final snow accumulations very high. The system will be intensifying further on Wednesday, with advection of very moist air mass towards Nova Scotia and Newfoundland.
Very heavy precipitation will develop towards Tuesday night into Wednesday morning, of both mixing precipitation, freezing rain, and heavy wet snow. Heavy Rain or wet snow will be confined to coastal areas only. It will be very heavy snowfall further north.
Although winds will also be increasing there, blizzard conditions will be less robust than across the areas further west of Maine as it needs drier snow which reduces visibility significantly.
The Nor’easter will continue growing and strengthening, thanks to the fueling from the warmer Western Atlantic and indeed the maintaining advection of very cold Arctic air mass from Canada into the eastern portions of the United States.