All Weather News

Tales From The Nor’easter

2 Nov 2012, 3:04 pm

Just as soon as our carved pumpkins from Halloween have been put out for display, we go into November, where they could be covered with snow or rain soon from a nor’easter.  I’m a long-time resident of the Northeast that now resides in Minnesota, so I’ve seen my share of nor’easters and they can bring a wide range of precipitation, winds, rough waves, temperatures and can sit and stay for a while or quickly glide right by.  Several factors go into a nor’easter and to what sort of weather it will bring to the northeast.  But first, lets look at what exactly makes a nor’easter what it is and why it is given that name.

The National Weather Service lists a nor’easter as:

A strong low pressure system that affects the Mid Atlantic and New England States. It can form over land or over the coastal waters. These winter weather events are notorious for producing heavy snow, rain, and tremendous waves that crash onto Atlantic beaches, often causing beach erosion and structural damage. Wind gusts associated with these storms can exceed hurricane force in intensity. A nor’easter gets its name from the continuously strong northeasterly winds blowing in from the ocean ahead of the storm and over the coastal areas.

These storms come around starting in the mid-Fall season (and through mid Spring), where the polar jet stream starts to dip down either into the Great Lakes or all the way down to the southeast and then, in either case, bend back up towards the northeast.  It is this shift in the jet, that allows cold, Canadian air, to sink across the northeast, cooling the temperatures.  But on the flip side, the Atlantic Ocean is still very much warm, with water temps in the 60s-80s.  So as an area of low pressure comes down along the jet from either the mid-west or from the Gulf of Mexico, it goes and moves along the jetstream that slides up towards the northeast.  The low pressure system picks up moisture from the warm ocean and then moves up the coast, where it runs into strong, northeasterly winds that pull it closer to the coast of the northeast.  The low pressure system then meets the chilly, sometimes Arctic air over the Great Lakes and the Northeast and starts to produce precipitation from rain to a wintry mix to snow, depending on the proximity of the cold air and the center of the low pressure.

The combination of the two airmasses (the Canadian high pressure and the low pressure system) will generate gusty winds from the northeast, blowing across New England and into the mid-Atlantic states.  It is the depending on the strength of the two systems, which will determine the power of the potential nor’easter.  Winds have been known to blow at hurricane strength (74+ mph) and bring heavy amounts of rain (causing flooding situations) and/or snow (causing the need for blizzard warnings t0 be put in place).

If the storm strengthens off-shore, it is the worst of two scenarios.  It means that cold air has moved all the way to the coast, thereby the precipitation to fall predominately as snow.  The northeast Megalopolis (the band of cities from Washington DC to Boston along the I-95 Highway) is the most densely populated  portion of the country.  It houses the national government and the financial heart of the country, as well as numerous ports of commerce and transportation centers.  So when this area is impacted by heavy, crippling snow, the whole nation suffers via shutdowns of transportation lines, power outages, and loss of business.

File:GreatBlizzardof2006.jpgA picture from the North American Blizzard of Feb. 2006.  The storm was a powerful one that had at one point, an eye-like feature, similar to a hurricane.  A record breaking 26.9″ fell in NYC, the most since the late 1860s. (courtesy: wikipedia.org)

If the storm strengthens on-shore, or closer to the shore, it is the better of the two scenarios.  Colder air has not invaded down to the coast, but instead stuck up in the higher elevations further inland.  The coastal cities from DC to Boston are in milder temperatures and will see rain.  But that doesn’t mean the coast is spared any snow.  As the storm pulls away, it will pull in colder air from the north.  So it can change the precipitation from rain to snow, and leave behind a chilly mess in its wake.  On the plus side, the snow totals will be low, the bad side, there could be a chance for freezing rain or ice to be coming down, depending on the temperatures across the land at the time. The nor’easter can take one of two paths typically.  Here is an image from weatherbug.com showing how the storm could bring snow to the northeast.

There is talk of a possible nor’easter for mid-week next week that could impact the already hard hit areas of New Jersey, New York and Long Island and portions of New England.  But with this talk, there is also the chance the system could not hit the region, but skirt on by.  There are several days to go of forecasting and model-checking before we start etching in stone the potential for a big storm to come through.  I will air on the side of caution that the potential is there, since most models hint that storm will form and be around Wednesday-Thursday.  How close it forms to land and how cold the temperatures are will determine it that area that has been hit hard by Superstorm Sandy, will see rain, sleet, snow or a combination of the three.
Stay tuned right here for more information, as well as tune into www.weathernationtv.com for details.  We will continue to monitor this situation and bring you the latest info as it comes in to us.

For now, enjoy the weekend, and if you are in the northeast, I wish you a speedy recovery. Meteorologist Addison Green

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