This soon-to-be-powerful coastal storm still presents a delicate and highly uncertain forecast.

Latest advisories from the National Weather Service: Pink=Winter Storm Warning, Teal=Winter Storm Watch, Purple=Winter Weather Advisory

Less than 24 Hours until First Flakes

There is no such thing as a "perfect" snow forecast. It is absolutely impossible — given today's level of research and technology — to precisely estimate how much snow Mother Nature will dump from a given storm. No man or machine can accurately predict where heavier mesoscale snow bands will ultimately set up, nor exactly who will get dry-slotted. Therefore, every forecast contains an inherent margin-of-error or confidence level. When a close-call situation develops, like Thursday's coastal storm, communicating a reasonable range of possible outcomes becomes a huge challenge.

While forecast confidence remains moderate at best, we're starting to get some clarity regarding how "on-the-edge" New Jersey will be. There is decent model consensus among our major forecast models that the Jersey Shore will potentially end up with about 5 or 6 inches of snow. That's fairly significant, and enough to cause travel headaches and school closings/delays. There is one notable outlier model — the short-range, mesoscale NAM — which at 00Z showed a nearly blank snow map for the Garden State, but at 06Z suggested over 2 feet of snow. This erratic (and downright comical) output suggests there's something funky going on within the model, and we need to disregard it altogether. Garbage in, garbage out. Throwing the NAM out the window works well, because all other model forecasts fall in line nicely.

Weather Dictionary

As you may know, I always strive to be technically precise here in the MDZ Weather Blog — especially when it comes to the very public-facing headlines and article summaries. Having said that, some of my colleagues have been throwing out some meteorological terms this week, and I want to clarify why some of them are/aren't OK:

--Bomb: Absolutely appropriate. Short for bombogenesis, a technical weather process that occurs when a storm's central barometric pressure drops at least 24 millibars in less than 24 hours. Such a cyclone intensifies, leading to heavier precipitation and stronger winds. This storm is expected to undergo such intensification just after it passes New Jersey — New England and eastern Canada are in trouble.

--Storm: Yes, it's a term that I use generously, and with purpose. The definition of a storm, according to the AMS Glossary of Meteorology, is "any disturbed state of the atmosphere, especially as affecting the earth's surface, implying inclement and possibly destructive weather." The shoe fits.

--Nor'easter: Sure, if you insist. This coastal storm actually won't drive the traditional ferocious northeasterly ("nor'east") winds, so I'm not using the term. But the Atlantic seaboard track and other impacts are similar enough for the moniker.

--Blizzard: Eh, not really. A blizzard requires: 1.) Sustained winds or frequent gusts above 35 mph, pushing 2.) Visibility below a quarter-mile, for 3.) at least 3 hours. (It has nothing to do with how much snow accumulates, or the snowfall rate.) Visibility will be reduced within snow bands, but it won't get that low.

--Whatever the Weather Channel haphazardly decided to name this winter storm: No. Just no.

Timeline

First flakes could arrive as early as 7 p.m. Wednesday, but it is more likely that New Jersey won't see initial snow until after Midnight. Snowfall will peak just in time for Thursday's morning rush hour, with bands of moderate to heavy snow expected between about 6 a.m. and Noon. Through the afternoon, show should taper off, ending completely by 7 p.m. Thursday at the latest.

Totals

Coastal storm = the biggest snow totals will occur along the coast. It also means there will be a very tight gradient between "no snow" and "lots of snow".

I've settled on a forecast of 5 or 6 inches of snow accumulation for coastal Monmouth, most of Ocean, southeastern Burlington, most of Atlantic, and most of Cape May counties. Between that swath and the NJ Turnpike corridor, 3+ inches is a good bet. To the north and west, just an inch or two. (See the map above for a visual depiction — it's purposefully very similar to what I published Tuesday evening.)

Overperformance

The "storm wiggle" disclaimer remains in effect. In other words, snowfall totals are very sensitive to the track of the storm. Even higher snow totals are absolutely still on the table, in case the storm drifts closer to the coast than expected. How high? Depends on just how close the center of the storm (and associated heavier snow bands) will creep to the Jersey coastline. 8, 10, 12 inches? Certainly possible.

The 28 inches that the NAM is pumping out? Highly unlikely.

For the record, I am not as worried about "underperformance" at this time — I'm confident it is going to snow, for at least the eastern two-thirds of New Jersey.

Advisories

The National Weather Service popped out a Winter Storm Warning for Ocean, southeastern Burlington, Atlantic, and Cape May counties, in effect from 9 p.m. Wednesday through 7 p.m. Thursday. That's the "sweet spot" in the state, with the heaviest snow expected. A warning means the combination of falling and blowing snow may create hazardous (if not impossible) travel conditions during and after the storm.

Monmouth County remains under a Winter Storm Watch. NWS has opted for a "wait and see" approach — this watch will either get upgraded to a warning or changed to an advisory as the snow gets closer.

A less-urgent, less-severe Winter Weather Advisory has been posted for southwestern NJ, including Cumberland, Salem, Gloucester, Camden, and northwestern Burlington counties.

Down the Shore

Overall, I'm not concerned about coastal flooding and beach erosion. This storm just doesn't have the strong, persistent easterly flow that would push massive amounts of ocean water toward the coast. Still worth watching, especially on the bayside, but I think coastal residents can exhale for now.

Dangerous Cold

In addition to potentially significant snow, this storm will also drive some fierce northwesterly winds through New Jersey. Gusts over 40 mph will lower visibility during snowfall, and make for some truly blustery conditions during and after the storm.

You think it's been cold this week? Just wait. High temperatures on Friday and Saturday will only reach the teens. The wind chill ("feels like" or "apparent" temperature) will be as low as -15 degrees! That definitely qualifies as "dangerous" cold.

Next weather blog update will be published Wednesday late afternoon/evening (by 5 or 6 p.m.)

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