UPDATE as of 8:40 p.m. Saturday...

An update to this forecast has been posted. Please click here to view the latest information about our impending winter storm.


UPDATE as of 4 p.m. Saturday...

Saturday afternoon, the National Weather Service extended the Winter Storm Watch to now include almost all of New Jersey (except the southern coast). I am a little puzzled by that decision, as a watch-warning means 5 to 7+ inches of snow is in the forecast — that is certainly not going to happen south of Interstate 195. I'm guessing they're just trying to cover the possibility for some accumulating snow and ice in the south.

I have updated my original post below with the new watch information.


Background

A storm area of low pressure will pass south of New Jersey from late Sunday to early Monday, driving snow and rain through the Garden State. (Tropical Tidbits)

A dusting on Thursday morning. Up to 3 inches on Friday morning. Up to 6 inches on Saturday morning. And here we 'snow' again, with the 4th winter storm in a row. This storm is likely to be the most significant and impactful of the bunch, with over a half-foot of snow looking likely for northern New Jersey.

I've been calling this setup a "classic" winter storm, mainly because the forecast is incredibly dependent on the exact track and temperatures. I think forecast models are finally coming around to a reasonable consensus.

The bottom line... If you're in northern or central New Jersey (at least), Monday morning's commute is going to be impacted by snow and ice on the ground.

Start Time

NAM model forecast as the storm arrives with a bang, Sunday afternoon. (College of DuPage Meteorology)

First raindrops and snowflakes are expected to enter southwestern New Jersey around 2 p.m. Sunday. That precipitation will spread northward to cover the entire state by about 6 p.m. Sunday. Travel will likely become very difficult after this time — it is very possible this storm arrives "hard and fast," with heavy snow/mix/rain soon after onset.

End Time

NAM model forecast as of early Monday morning, showing the snow and rain gradually departing NJ. (College of DuPage Meteorology)

I have to leave a bigger window on the tail end of the storm, as models aren't in complete agreement about the conclusion. I'm thinking the storm will start to taper off 3 a.m. Monday, wrapping up completely by around 9 a.m. Monday. As I'm sure you're aware, that timeline carries at least some snowfall through the Monday morning commute.

Snow Totals

Here is my first stab at a snow map for this system. I think my lower bounds and upper bounds are sensible estimations of the ultimate outcome.

Our latest forecast for the Sunday afternoon to Monday morning winter storm, as of Saturday morning.

—North Jersey... It looks like you're in the snow bullseye for this storm. I like 6 to 9 inches as a most likely scenario, in pretty much the same area as the Friday night-Saturday morning snowfall.

—Central Jersey... Once again, caught in the middle of big snow and big rain. There is a good chance that areas in and around Mercer, Middlesex, and Monmouth counties (in addition to part of the Interstate 295 corridor) will flip between snow, wintry mix, and rain as the storm rolls on. Any amount of mixing will obviously limit accumulations. I've settled on a 3 to 6 inch snow forecast here — keep in mind, there is a good chance we'll need to refine that further over the coming day.

—South Jersey... I have to be very careful here. While "almost all rain" is the probable case, we could still see a bit of snow throughout southern NJ — especially away from the coast. That's why I've assigned a 0 to 3 inch snow forecast — keep in mind, both ends of that range are possible.

Winter Storm Watch

The National Weather Service has issued a Winter Storm Watch for 18 counties in North Jersey: Bergen, Burlington, Camden, Essex, Gloucester, Hudson, Hunterdon, Mercer, Middlesex, Monmouth, Morris, Ocean, Passaic, Salem, Somerset, Sussex, Union, and Warren. The watch is effective from 1 p.m. Sunday to 7 a.m. Monday.

A Winter Storm Watch has been issued for 18 counties in New Jersey from Sunday afternoon to Monday morning.

A watch is simply a formal heads-up that you need to "watch" out for potentially hazardous wintry weather within 24 to 48 hours. If the forecast for major snow (6+ inches) holds, the watch will be upgraded to a warning on Sunday morning. If the forecast calls for less snow, it would become an advisory instead.

Confidence

This forecast is not quite a slam dunk yet, particularly in regards to the location of the all rain vs. significant snow boundary. Yup, the "wiggle" factor is definitely at play! I would describe my confidence level "moderate" in this forecast at this time.

—Could we end up with more snow overall? Sure. Any combination of colder temperatures, heavier snow bands, and/or miscalculated snow ratios could result in over performance. A few (past) model runs have even suggested double-digit snowfall (10+ inches) somewhere in New Jersey.

GFS model raw snow accumulation forecast, as of Monday morning. This is the outlier lowball scenario, with only 3 inches of snow in NJ. (College of DuPage Meteorology)

—Could there be less? Perhaps. The GFS model in particular shows a much drier solution. We'd still see "plowable snow" — but closer to 3 inches than 6+ inches. Also keep in mind, zero snow is a distinct possibility for the southern half of the state.

So yes, I have to leave some "wiggle room" in this forecast given the lingering question marks. In general, I consider myself to be comfortable with a forecast when there's an approximately equal chance of "busting" high or low. And that's about where I land presently with this snow map. The forecast will continue to evolve and adjust as the storm draws closer — that's how the meteorology game works.

Down the Shore

This is not really a coastal storm. We are not going to see an extended period of strong northeasterly or easterly winds, driving ocean water toward the coast.

WaveWatch3 model showing the ocean getting churned up by strong low pressure on Monday. (Tropical Tidbits)

Still, a storm of this magnitude and orientation will churn up the Atlantic bit. Surge models are picking up on a half-foot to a foot of surge along the Jersey Shore for Monday morning's high tide cycle.

That's not much. But there are some vulnerable places along coastal waterways that could see minor flooding with that degree of water rise.

Impacts

For much of New Jersey, we have only had one winter storm of this magnitude so far this season — November 15th.

Road conditions will go downhill rapidly from late Sunday afternoon through Sunday night. Travel could be very difficult for some time Monday morning, until road crews can adequately plow and salt the roads.

For the record, pretreatment or "brine" will only help at the storm's onset. This magnitude of snow event will require a lot more effort from crews to get the roads down to blacktop. And therefore, it will require a lot of patience from drivers.

School delays and/or closings are likely for Monday. As usual, I recommend that school officials wait until the early morning hours to make that decision based on actual conditions. That is especially true for districts in the central and southern portions of the state, where snow accumulation is less certain.

Watching and Waiting

I will be covering this storm and the latest forecast all weekend. (Well, aside from taking a break to shovel my driveway from the 4.2 inches of snow last night.) Depending on how things develop with the afternoon model runs, my next CMDZ weather blog update will either come Saturday evening or Sunday morning.

Dan Zarrow is Chief Meteorologist for Townsquare Media New Jersey. Follow him on Facebook or Twitter for the latest forecast and realtime weather updates.