We have all seen it before -the “bread and milk” index displayed on local news forecasts and store shelves emptied of non-perishables, while “Winter Storm Warning in Effect” flashes on electronic screens along the highway. Any seasoned New Englander knows to fill the tub and grab the generator fuel and have the snow shovels and blowers at the ready. They also often have the familiar cold-weather New England “yard-sculpture” -a perfectly curated log-pile stacked neatly somewhere near the house. Winter storms are obviously common events mastered by New Englanders for generations, but perhaps it might be worth taking a look as to what exactly cooks up these infamous storm’s we call nor’easters.
The term nor’easter is fairly common in winter weather vernacular and refers to strong areas of low pressure along the U.S. East Coast featuring winds that move in from the northeast off the Atlantic Ocean. These storms are most usually associated with winter and snowstorms as they are most common and strongest between September and April, but nor’easters are possible year-round, as long as a low-pressure system fits the criteria. Just as no two snowflakes are alike, no nor’easters are exactly alike, but they can usually be sorted into categories, named after the researcher who came up with the system in 1946, J.E. Miller. Although not every nor’easter is a Miller System storm, the majority of them can be classified as such. There are five categories of Miller System storms, Types A-B-C-D-E, but the majority of storms fall into the Miller Type-A and Type-B categories.
To over-simplify and provide a quick visual of what pressure systems do, consider that high pressure is literally that -downward gravitational pressure that suppresses storm development -a lid, if you will, keeping things contained. Storms need the ability to ascend into the atmosphere and interact, with little restraint, with moisture and air masses to become significant. High pressure keeps all of that fun in check. Low pressure, however, means the “lid” is off and the atmospheric mayhem is allowed to commence and storms develop. The placement of high-and-low pressure systems also act as buffers that create pathways to guide and set the track for storms -much like the bumper pads on a bowling lane. Now that you have a visual of pressure systems, let’s talk about the Miller Systems.
The first Miller category, Type-A, includes nor’easters that primarily develop near the Gulf Coast or East Coast along an old cold front or the boundary between marine and land air masses. These types of nor’easters are considered “classic” nor’easters. For a Miller Type-A system to develop, high pressure must be in place near the eastern Great Lakes and a stationary boundary of low pressure is usually stationed off the southeast coast. This low-pressure line allows the cold, northern air mass to travel down and mix with the warmer air mass from the coast. This causes a system to develop. This growing storm system will then ride the buffered track up the east coast. By the time it reaches New England it is usually a significant system with a lot of moisture which usually falls as heavy snow.
Miller Type-B nor’easters are a bit more flamboyant with their wintry party as they tend to gift the inland states with blizzards and ice storms that make headlines and give headaches. Low pressure develops over the plains and rushes eastward. These systems approach the Northeast from the west, often through the Ohio Valley, bringing precipitation and ice to the Midwest on their journey. As with Miller Type-A storms, there is a delineation between rain and snow, but this time it’s more of a north-south split, rather than an inland-coastal split.
One thing that is unique to Miller Type-B systems is that they get a bit jumbled when they hit the Appalachian Mountains. The change in elevation and flow of terrain causes the initial low-pressure system to weaken as the central pressure goes up to accommodate the mountains, but this sets the stage for the low to then redevelop on the eastern side of the mountain range. This process is also known as a “center-jump.” Regardless of this momentary hop over the mountains, Miller Type-B systems are undeterred in unleashing a bit of chaos as they travel.
Sometimes, a nor’easter comes in the package of an Alberta Clipper System. Alberta clippers are another common type of winter storm, but only occasionally fall into the category of a nor’easter. An Alberta Clipper is a fast-moving area of low pressure that moves southeastward out of the Canadian Province of Alberta, through the Plains and Midwest. This type of winter storm qualifies as a nor’easter *if* it follows the path of a Miller Type-B storm and eventually reaches the East Coast to cause the northeasterly winds coming off the Atlantic Ocean that are required to classify a storm as a nor’easter.
Each nor’easter system can have various types of precipitation depending on where it is on its developmental journey. Initially, all the precipitation from a nor’easter falls as snow due to the low pressure allowing high (freezing cold!) atmospheric development. It can stay snow if it does not encounter a warm air mass on its way down. If it does encounter warm air, a few things can happen. First off, if the warm air mass is dense and stretches to the surface of the earth, you will have rain. If the warm air mass over a part of land is less dense, and there is an underlying horizontal line of cold air again before the precipitation hits the ground, you can have refreezing which results in either freezing rain or sleet. For freezing rain, the cold air mass above the ground has to be thicker and a more intense temperature change, and for sleet the cold air mass above the ground has to be thinner and with less a temperature change so the freezing is less instantaneous.
Be it a Miller System or an Alberta Clipper, nor’easters have long been commonplace due to the natural weather patterns in this part of the world, but they have made headlines and become local lore since we started recording weather events and collecting data on them. Some of the most notable nor’easters (that many readers are sure to recall first-hand) are:
The Great Blizzard of 1888. This monster storm dropped up to 58 in. of snow in some areas and drifts as high as 50 ft. The blizzard lasted three days. The impacted areas were centered in New York City.
The Storm of the Century in 1950. This nor’easter slammed from New Jersey northward and caused $70 million in storm damage. Variants from 33-62 in. of snow were left behind as well as downed lines and trees from 60 mph winds.
The Ash Wednesday Storm of 1962. The Ash Wednesday Storm lasted from March 5-9 and left destruction from Florida to New England and some places, such as Ocean City, under 4 ft. of water. It also caused mayhem with 70 mph winds and 42 in. of snow.
The Northeastern United States Blizzard of 1978. This infamous, deadly blizzard left todays equivalent of $1.85 billion dollars in damage. Over 10,000 cars were left stranded after a two-day white-out buried the seaboard from Philadelphia to Boston in 27 in. of snow and reached hurricane-force winds.
Storm of the Century 1993. What started as a nor’easter in March 1993 ended as a disaster dubbed the “Storm of the Century.” This record-breaking nor’easter was the result of a rare catastrophe when three massive, and separate, weather systems unexpectedly mingled over the Gulf of Mexico. This combo from Hades affected states along the East Coast, from Florida to Maine, as well as interior states that didn’t often feel the effects of powerful nor’easters. $Six billion dollars in damage and up to 56 in. of snow in some areas.
The Nor’easter of 2016. This damaging weather event spanned two days across the mid-Atlantic and up into the Northeast and left behind 36-52 in. of snow in some areas. In addition to the heavy snow, there were 85 mph wind gusts and six tornadoes spawned as it traveled up the coast.
There are many more famous nor’easters to learn about and many more to come and experience first-hand. Given what you now know about the Miller System, perhaps you can spend your snowy days the next few weeks reading about the famous blizzards and figuring out which Miller-Type each of them was. You should also be able to identify the types of blizzards forthcoming. Don’t forget to make sure that in addition to learning about these weather systems, you are preparing adequately for them -but here in New England, where nor’easters are as much a part of life as lobster rolls and Dunkin’, you hardly need a reminder from this Utah-born and raised transplant. Stay safe and warm, readers!