CALIFORNIA NYACK SHELL STATION SLIPPERY ROADS SIERRA SNOW
Snow.
Of all of the weather events New Jersey sees, snow can cause the biggest emotions.
There are the snow lovers, the snow haters, the “one-and-done” people — those who like one snow and are then fine for the season — and everybody in between.
In New Jersey, I counted nine ways in which the state can bring out these emotions. Nine ways to snow.
Here’s a look at how they happen and why they happen. They’re generally grouped into three categories: large-scale storms, small-scale storms and snow caused by wind and water.
Large-scale storms
1 and 2) “Miller A” and “Miller B” storms
When you think of your classic nor’easters, think of Miller A and Miller B low-pressure systems.
The name comes from J.E. Miller, the researcher who came up with this naming system for East Coast storms in 1946.
They can happen any time of the year, bringing rain, wind and coastal flooding. However, it’s during the winter when they’re most frequent, and most apt to bring snow, sleet and freezing rain.
Whether it’s a Miller A or Miller B depends on where the low-pressure system originates.
In a Miller A setup, the low-pressure system develops off the southeastern United States coast or the Gulf of Mexico. It then intensifies as it moves up the East Coast before turning to the northeast somewhere in the Mid-Atlantic, Northeast or Eastern Canada.
The blizzard of March 13-14, 1993, was an example of a Miller A.
Miller B storms are a little more common but typically not as strong as Miller A storms.
Miller B storms start as low-pressure systems moving east from the Great Plains and Midwest.
The system weakens as it hits the Appalachian Mountains. However, the low reforms on the other side of the mountains, either over the coastal states or just out to sea. From there, it’ll strengthen as it moves north. Like a Miller A, it’ll move to the northeast.
For New Jersey, these storms are best known for bringing more snow northwest of the New Jersey Turnpike, a mix along the turnpike and mostly rain to southeastern New Jersey. However, a shift in the track 75 miles east can bring snow to the whole state. The opposite can bring rain to all but the mountains of northwest New Jersey.
3) Alberta clipper
As the name implies, these storms hail from Alberta. They form on the lee, or eastern side, of the Rocky Mountains.
They’re fast-moving, cold, fairly weak low-pressure systems. They travel from Canada to New Jersey in two or three days.
If New Jersey is near or north of the low-pressure center, a few hours of light (less than a half-inch per hour) to moderate (a half-inch to an inch per hour) snow is likely with gusty winds.
If the Garden State is south of the low, it’ll usually rain. Behind it typically comes a cold shot of air and gusty winds.
Alberta Clippers happen numerous times a winter in New Jersey.
Small-scale storms 4) Norlun trough
Along with Miller storms, norlun troughs give meteorologists the most headaches.
A norlun trough is an axis of shifting winds on the northwest side of a low-pressure system, which spins counterclockwise.
Snow with a norlun trough is usually heavy, narrow in size and only lasts a few hours.
This private snowstorm was put on full display Dec. 5, 2018. Brigantine reported 7.5 inches of snow, with 5.0 inches in the Beesleys Point section of Upper Township. However, West Cape May reported nothing. Just flurries were seen near Forked River in Lacey Township.
A norlun trough requires colder-than-usual air aloft and relatively mild ocean waters to cause unstable air to develop. Around 15,000 to 20,000 feet in the atmosphere, a low-pressure system provides upward motion to create snow. At the surface, winds that meet in a localized area provide additional upward motion.
5) Snow squalls
The wintertime equivalent of brief but intense warm-season thunderstorm is the snow squall.
Whiteout conditions that bring dangerous, even deadly road conditions, with strong winds for a brief time (less than an hour), are usually the case with these.
Snow squalls are usually caused by cold fronts with Arctic origins. The squall itself forms either just in front of or behind the front.
While not to the same degree as with warm-season storms, these fronts form a relatively large amount of unstable air. That creates the snow.
Snow caused by wind and water
Snow caused by wind and water comes from low-level clouds — 1,000 to 5,000 feet high. Previously discussed forms of snow come from clouds 10,000 or 20,000 feet high.
6) Lake-effect snow
The same snow that falls around the Great Lakes throughout the year usually makes its way to New Jersey a few times a year.
Typically, though, by the time it reaches New Jersey, it’s light snow, having been weakened by the Appalachian Mountains. Sometimes, it’s even rain by the time it reaches us.
Still, it can coat the ground or bring a light accumulation, typically north of Interstate 195, which runs from near Trenton to Point Pleasant.
At the most basic level, lake-effect snow develops when cold winds blow over a relatively mild body of water. However, the cold air must typically blow over the water for at least 60 miles. Winds at the surface must be from nearly the same direction as a few thousand feet above.
Lake-effect snow season stops when the Great Lakes freeze over. This usually happens on Lake Erie, though with declining frequency. However, it can also happen on Lake Huron, Lake Ontario and Lake Superior.
7) Delaware Bay-effect snow
It takes a lot, but it has happened, giving lower Cape May County a snowstorm all to themselves.
Similar to lake-effect snow, it’s caused by cold air going over the relatively milder Delaware Bay. Unlike some of the Great Lakes, the Delaware Bay does not freeze over significantly. Therefore, this can happen at any point during the winter.
However, there are challenges to making this happen. The bay is fairly small. Therefore, during the winter, it needs to be warmer than usual to have enough moisture available so that when the cold air goes over it, snow develops in addition to clouds.
Furthermore, winds need to be nearly due northwest to capture the full length of the bay.
8) Long Island Sound
Even less common is snow that develops off the Long Island Sound and goes into North Jersey.
While the sound is longer than the Delaware Bay, a colder than usual east-northeast wind is needed to pick up the moisture off the sound and convert it to snow.
At Teterboro Airport in Bergen County, northwesterly winds are the most common during the winter.
9) Ocean-effect snow
Why use a bay or lake when you can use an entire ocean? With an essentially limitless amount of fetch over the Atlantic Ocean, ocean-effect snow can happen whenever the difference in temperature between onshore near-surface winds and the water is large enough.
This will come from one of two weather events, typically.
First is a cold east-to-northeast wind around an arctic high-pressure system in Quebec or Atlantic Canada.
Second would be in the later stages of a nor’easter, when cold northeast winds wrap around a system.
In the latter case, low-level ocean-effect snow can fall below the large-scale clouds of a nor’easter. In New Jersey, Ocean and Atlantic counties see this the most.
What about the polar vortex?
The polar vortex can start the process that brings New Jersey snow. However, the vortex is a low-pressure system in the stratosphere. In the poles, that starts about 20,000 feet high. In New Jersey, that’s about 35,000 feet high.
Surface low-pressure systems tend to be more directly responsible for cloud and snow formation.