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What is a nor’easter, and could one affect the DMV this weekend?
For people living along the East Coast, the word nor’easter can immediately bring to mind howling winds, pounding surf, coastal flooding and, during the colder months, heavy snow. But what exactly makes a storm a nor’easter?
WASHINGTON - For people living along the East Coast, the word nor’easter can immediately bring to mind howling winds, pounding surf, coastal flooding and, during the colder months, heavy snow. But what exactly makes a storm a nor’easter?
A nor’easter develops when a surface low is strengthened by upper-level winds near the East Coast of the United States.
Despite the name, a nor’easter isn't simply any storm that produces northeast winds. It is a powerful area of low pressure that develops along or near the East Coast (typically within 100 miles) and often tracks north or northeastward, intensifying as it moves toward the Northeast. The strongest winds typically found on its western and northern sides blow from the northeast, giving the storm its name.
Winds turn out of the northeast on the northern and northwestern flank of the storm, giving them their signature name.
Nor’easters can happen at any time of year, although they are most common from September through April and tend to be strongest during the winter when the polar jetstream is at its strongest. Contrary to popular belief, a nor’easter does not have to produce snow. Nor'easters can happen during both the fall and the spring, where the same storm structure can produce heavy rain, strong winds, coastal flooding and rough surf.
RELATED: Nor’easter brings heavy rain and strong winds to DC region this weekend
Biggest impacts: At the shore
The National Weather Service is warning about dangerous shore erosion and 6-12ft waves along coastal areas of Delaware, Maryland, and Virginia this weekend.
In inland cities like D.C. and Baltimore, the headlines for a nor'easter often involve high rainfall, or in the winter, snowfall totals, and some gusty winds. When they come without the snow component, they tend not to grab the headlines locally, as their impacts are a little less impactful. No matter the season they occur in, it is always the coastline that has to deal with the most significant impacts of a nor'easter...storm surge and beach erosion.
Sustained and especially increasing winds for a prolonger period of time from an easterly or northeasterly direction forces a tremendous amount of ocean water against the shoreline. Large waves can batter coastal areas for days on end, doing a tremendous amount of damage to coastal beaches and dunes, and often leading to coastal flooding, especially when paired with high tide cycles.
What to expect this weekend
The European Forecast Model for this weekend’s storm system, showing the most impactful rainfall at the coastline, while inland areas like DC do not get much.
The weekend forecast heading into the first weekend of fall will differ vastly depending on if you are reading this from closer to the metro Washington, DC area or closer to our area beaches, like Ocean City, MD or Bethany Beach, DE.
Similar to rainfall, the highest gusts locally with this early season nor’easter will be right along the immediate coastline.
At the beaches, surf has been high all week as onshore winds have been a near constant thanks to a ridge of high pressure centered to the north of our region directs winds and water towards the coastline. The surface low that will become the nor'easter will begin to deepen through the day on Wednesday. Winds and ocean waves will increase in intensity as the day goes on, with peak gusts expected to be 40-50mph along the coastline by Wednesday night. Similar conditions are expected throughout the day on Thursday and Friday, with the immediate shoreline seeing wind gusts exceeding 50mph at the worst of it.
The National Weather Service is warning that peak wave heights could reach 6-12 feet between Wednesday night and Friday afternoon.
RELATED: What is a nor’easter and a bomb cyclone? How major East Coast winter storms form
Sustained winds of 20-30mph with gusts near 50mph will cause major impacts at the beaches heading into the first weekend of fall.
By Saturday, the storm should continue to gather intensity but will shift northward towards New England. This will put the beaches into the southwestern quadrant of the storm. Winds will remain gusty here, likely 30-40mph gusts on Saturday, however in this quadrant of the storm winds shift to an offshore direction, meaning winds are blowing from the land out into the ocean. This will quickly and significantly improve the coastline situation by the weekend, through gusty winds and occasional rain showers and expected to continue through Sunday.
But in terms of when will the nor'easter have the worst impacts on our area beaches? That would be on Thursday and Friday of this week. Expect cool temperatures to persist through the weekend as well.
While we cannot rule out some passing showers through the weekend, especially on Sunday, the track of the nor’easter should keep the heaviest of the rainfall away from the immediate DC area.
If you are farther inland, the impact from the storm will be significantly less impactful. For one, when the storm passes by the Mid-Atlantic, it will not be hugging close to the coastline but will instead be well offshore. This is due to the track of the upper-level low that will help intensify the storm. It's track across the Mid-Atltantic will help "shield" the DC region from too many of the impacts in terms of rainfall.
While the beaches have rough weather with onshore winds on Thursday and Friday, the weather here in DC will actually be pretty pleasant. Thursday we will fight some cloud cover, but should see some sunshine breaking through during the afternoon, while Friday looks overall like a nice fall afternoon with a bit more sunshine. It's as the storm hits peak intensity to our north on Saturday that the DC area could see impacts in terms of some gusty winds, though peak gusts are only expected to be around 30mph. As the storm then starts to weaken and pull away on Sunday, we could also see some stray showers come across, but we are not expected any sort of major rainfall event from this early nor'easter, at least not given the forecast track of it through the middle of this week.
Are there any winter implications?
Nor’easters are common during El Niño years, though they can be hit or miss in terms of snowfall as the cold air supply is always the main concern.
While fall has only just begun, hearing the term nor'easter so early in the season has a lot of people wondering, will this be something we expect to see more of in the winter ahead? Could they bring us perhaps some bigger snowfalls this year?
The short answer is everyone's favorite weather word...maybe. What is true is that coastal storms and nor'easters are much more common during El Niño winters compared to neutral or La Niña winters, thanks to a more active moisture feed from the south. With the one guarantee for the winter ahead being an El Niño winter (likely strong to very strong intensity) this would make the potential for additional nor'easters very likely. The biggest question mark will be will there be strong enough cold air supply this weekend that we are talking snow instead of rainfall. There have been plenty of El Niño winters where nor'easters bring our area northing more than a chilly, heavy rain.
We'll be looking over the data in the weeks ahead, so expect your Winter Weather Outlook from the Fox 5 Weather Team soon!
The Source: Information in this article comes from the FOX 5 Weather Team and the National Weather Service.