Light accumulations of snow and ice will be possible in North Jersey late Monday, but a transition to all rain by Tuesday will limit wintry impacts.

Monday night's winter weather will likely be limited to the northern third of New Jersey.
Monday night's winter weather will likely be limited to the northern third of New Jersey.
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The Bottom Line

Snow! It's hard to believe after this incredibly warm December, and especially after temperatures make another run for 70 degrees on Sunday... But our first real taste of snow and ice is in the forecast as we enter the last week of the year.

However, this storm is expected to produce nothing more than a "taste" of winter for New Jersey. Expect light accumulations of snow and ice in North Jersey on Monday night (up to about 2" in the higher elevations of Sussex County). Down to about the Raritan River, a dusting of snow and light icing will be possible. This brief shot of wintry weather will be followed by a day of rain and above-freezing temperatures on Tuesday.

Setup

A powerful storm system will dig across the middle of the United States between now and Tuesday. Snow and ice will drop across a wide swath of the Southern and Central Plains and the Great Lakes. As this system clips New Jersey from Monday night through Tuesday, we will see at least some precipitation from it. The precipitation type (rain, snow, sleet, freezing rain) will be heavily dictated by temperatures. Most notably, air temperatures are expected to increase, as a warm front pushes through New Jersey on Tuesday morning.

Timing

There is fairly good agreement among this afternoon's forecast model suite that onset of this storm system will be Monday evening, likely between about 8 p.m. and 2 a.m. (The NAM model shows some precipitation moving in a bit earlier, putting the first drops/flakes on top of New Jersey by early evening on Monday.)

The precipitation will spread throughout the entire Garden State by early Tuesday morning. Meanwhile, overnight temperatures are expected to be cold enough for at least the northern third of the state (north of I-78) to experience a period of snow and/or wintry mix (snow, sleet, freezing rain). Most of Central Jersey and all of South Jersey will experience rain only from this storm.

By Tuesday morning (probably by the time you wake up), an injection of warmer air will cause any wintry precipitation to transition to all rain. So any snow and ice that has accumulated will quickly melt and/or wash away.

Accumulations

Keep in the mind, the ground is still very warm, thanks to the persistent above-normal temperatures so far this winter season. (Soil temperatures are currently in the 50s for most of New Jersey.) Therefore, ice accumulation will occur ONLY if we see a prolonged period of steady snow, sleet, or freezing rain. There's going to be a pretty narrow time window for this to occur, given the eventual transition to all rain I previously mentioned.

The worst-case scenario at the moment would involve snow accumulations of about 2 inches in and around Sussex County, New Jersey. Again, this would only play out if temperatures are cold enough to sustain several hours of steady to heavy snowfall. Meanwhile, a dusting of snow could occur as far south as about the Raritan River. (I should also mention that the 12Z GFS actually pumps out about 6" of snow for the northern tip of the state... I just don't buy big accumulations here in NJ, given the warm ground and the forecast temperature profile.)

A scenario that could be just as bad is a wintry mix-icing situation. If sleet and freezing rain are the dominant precipitation types, roads could be slippery for the beginning of Tuesday morning's commute. (It doesn't take much ice to create huge travel problems.) The icing would be most serious along elevated surfaces, such as bridges, overpasses, on-ramps, and off-ramps. And once again, such icing problems would be limited to North Jersey, and the ice wouldn't last long as rising temperatures and a transition to rain would quickly melt it.

Finally, there is a definite chance that we see only a few snowflakes and sleet pellets flying around in the air, with nothing accumulating on the ground.

Confidence

At this point, confidence in our forecast is high enough to assert that this storm on Monday night and Tuesday morning will not cause widespread, significant problems for New Jersey. This is especially true from about Mercer and Monmouth counties southward, which should see only rain from this storm system. So, as we often say, you do NOT need make a trip to the store for bread and milk...

However, the location of how far south the rain-ice-snow line will drift during the storm is still in question as the exact precipitation type is oh so sensitive to the exact temperature. That will, of course, make all the difference whether your neighborhood sees all rain, some icing, or some accumulating snow.

At this point, I think it's important to keep an eye on the forecast, especially if you plan to be out and about early Tuesday morning. We will continue to bring you regular updates as this forecast evolves. And of course, during and after the storm, you can count on us for the latest traffic, closings, and storm cleanup information too.

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

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