NJ nor’easter update: Latest storm timeline, snow totals, and impacts
UPDATE... This article is outdated...
For the latest storm forecast information, please refer to my newest weather blog post.
The Bottom Line
The latest data is in. And we are getting a clearer picture of how this bona fide nor'easter will impact New Jersey over the next 36 hours or so.
Yes, it is going to snow. Potentially a lot. But only in northern New Jersey. (And points north.)
I think it's safe to say at this point that wintry impacts south of the Interstate 78 corridor will be limited. Although not exactly zero. There will probably be some "conversational snow" along the way. Maybe some slushy roads. Wind and coastal flooding will become issues during and after the storm too.
I'll call confidence "medium" at this point. The timeline has held firm over the past few updates, which I believe is the most important part of the forecast. There are still some question marks and bust potential surrounding above-freezing air temperatures, the chance of and positioning of heavy snow bands, and intrusion of dry air. All of those factors would potentially affect how much snow is able to accumulate. But I like where my forecast stands compared to model guidance and other public outlooks.
For this post, let's focus on breaking the storm timeline into three phases. And then we'll talk about accumulations and other impacts, including wind and surf. The forecast for the rest of the week turns quieter, and quite mild.
Phase 1: Just Rain (Monday)
Conditions on this Monday morning already range from damp to wet, as pockets of the state picked up upwards of a tenth of an inch of rain overnight. That is the story of Monday daytime — raindrops.
Drizzle and showers will continue to moisten your day and keep skies gray from morning through afternoon. There is a chance that snowflakes mix in, but only in NW NJ and only through about Noon.
High temperatures will reach the lower to mid 40s Monday afternoon. Well above freezing.
After about 4 p.m., rainfall should become steadier and heavier through the evening hours. But through at least 9 or 10 p.m. Monday evening, it's still just liquid.
Phase 2: Transition (Monday Night)
Temperatures will start dropping late Monday evening (again, after about 9 or 10 p.m.), forcing an eventual transition from rain to snow. By just before daybreak Tuesday morning (5 or 6 a.m.), all of New Jersey should be cold enough to sustain snowflakes. And road conditions could go downhill quickly, as snow starts to accumulate overnight in colder North Jersey — especially if we get a band of heavy snow to set up.
However, to the southwest, drier air will start to work in on the back side of this system. So in South Jersey, the "faucet" will get turned off by around daybreak Tuesday morning. That will limit what falls from the sky going forward to just showers.
Overnight low temperatures will dip into the lower to mid 30s. At or above the freezing mark, again making it very hard to get snow to stick. That also contributes to it being a heavy, wet snow. (FYI, all my snowfall calculations are based on an average 7:1 snow to water ratio.)
Phase 3: Snow Continues (Tuesday)
One of the biggest differences in model guidance right now is determining when the storm fizzles out and moves away enough for snow to end.
We are still going to see snowflakes falling during the daytime hours on Tuesday, as the coastal low meanders just northeast of NJ. Snow may be heavy at times, especially to the north and east. And again, what falls on Tuesday will probably be snow or at least wintry mix — high temperatures will be in the upper 30s to around 40 degrees.
As the main body of this powerful coastal storm system pulls away, the pressure gradient force will also increase our winds. Primarily after the storm's precipitation wraps up — northwesterly gusts over 40 mph are possible through Tuesday night.
Accumulations / Impacts
I am still liking a 6 to 12+ inch forecast for far northern New Jersey, above Interstate 80. There are lingering questions about storm track and snowfall intensity. But my gut tells me this will be the most impactful winter storm of the season.
Just to the south of the "snow burial zone" will be a narrow zone of moderate snow accumulation, on the order of 3 to 6 inches. Leading to the potential for moderate travel issues. This basically translates to "the rest of North Jersey," between I-80 and I-78.
South of Interstate 78, wintry impacts will be limited to an inch or two of accumulation, at best. Roads could get slushy, especially the farther north you are.
South of exit 9 on the Turnpike, you will probably see snowflakes at some point. But little to no snow accumulation is anticipated. I got a little lazy here, and decided not to draw a definitive "zero" contour — but those south of Interstate 195 will see very little snowfall here.
This is a tough forecast to make, and even tougher to fully comprehend. Look at the snow forecast for places like Warren and Bergen counties — literally ranging from an inch to a foot! I'm glad I don't have to forecast for New York City anymore, because all five boroughs could see drastically different snow totals from this one. That's how tight the snowfall gradient will be. Blur your eyes, stay as flexible as possible, prepare for the worst, and hope for the best.
In addition to snow, regular wind gusts of 40 mph are likely, shifting from east-northeast to northwest. The strongest gusts will actually come after the storm's precipitation wraps up.
Coastal flooding is not longer a huge concern. However, a foot or two of water rise is possible at high tide Monday night into Tuesday morning, leading to spotty minor category flooding. Heavy surf and big waves could cause moderate beach erosion up and down the Jersey Shore.
A Winter Storm Warning has been issued for Morris, Sussex, and Warren counties from 6 p.m. Monday until 6 p.m. Tuesday. And a warning is posted for western Passaic county from 10 p.m. to 6 a.m. Wednesday. (For the record, that end time seems awfully late.) That is the area of the state subject to downright dangerous travel conditions due to snowy roads and severely reduced visibility.
A less urgent, less severe Winter Weather Advisory has been put out for eastern Passaic and western Bergen counties. I suspect — if the forecast holds — we will see more advisories issued before the storm arrives. (Without that snowfall sweet spot, down to the I-78 corridor or so.)
We may see some advisories for wind and coastal flooding added to the mix at some point too. But nothing yet.
In terms of my coverage plan, I'll have regular weather updates all day. And then I'll be in the weather center extra early Tuesday morning to carry you through the worst of the wintry weather.
In terms of digital coverage, I may or may not take one more stab at a final snow map and fresh blog post Monday afternoon. I'm leaning toward yes, but let's see how the forecast trends.
The long-range forecast looks windy through Wednesday, although the sun comes out and temperatures return to the 40s.
Thursday looks great. Partly sunny, dry, calm, and mild, with highs in the mid 50s or so. We might even touch 60 degrees on Friday, as clouds thicken up.
Our next storm system arrives at the start of the weekend, Friday night into Saturday morning. It looks like just a rainmaker, followed by another blustery cooldown into Sunday.
Dan Zarrow is Chief Meteorologist for Townsquare Media New Jersey. Follow him on Facebook or Twitter for the latest forecast and realtime weather updates.