Sunday Snowstorm Chances Increasing

Discussion: Light snow is pushing across NJ from W to E as expected. There’s still a slug of precipitation reaching back to W PA, so NJ can expect about 3-6 more hours of this. Nothing crazy but most of it will stick due to the colder surface and that could make things slick for today’s rush hour commute home. The snow map we issued yesterday was for this today…separate from the Sunday-Monday (Jan 19-20) signal we’ve been discussing. We have still yet to issue a snow map for Jan 19-20 but that will come tomorrow. Today is one more day of model analysis and I’m glad I waited for a few reasons.

First, the energy associated with Sunday’s snowstorm is now over land in the W US. It came off the Pacific this morning and is now better sampled by the more abundant sensors and weather stations that feed the models. This typically triggers adjustments in forecast expectations and today it has cause a shift to a snowier solution for Sunday-Monday.

Second, today’s data confirms a trend in timing. This is no longer a Monday (Jan 20) only snowfall. It’s now more of a Sunday noon to 9pm idea with maybe some snow pushing past midnight into Monday. But from hereon out I will probably just refer to it as Sunday’s snowstorm for NJ.

Third, today’s data also confirms a better timed trough interaction with the surface low. This has allowed expected snow totals to rise above just a light snow event, into more of a significant/plowable outcome for much of New Jersey.

Let’s review the latest model guidance. The Canadian data package (GGEM transitioning into RGEM) remains the furthest NW with the precipitation shield and low track. This brings more of a NNJ/CNJ hit leaving SNJ/SENJ to possibly deal with some mixing. The GFS is sort of a middle of the road hit for most of NJ. The Euro is a lighter snowfall but is sitting on the furthest SE side of the overall spread. The UK model also supports a nice snowfall Sunday. While it’s rendered in green, that’s all snow for NJ with line of freezing offshore. Here are their outputs from today’s 12Z model suite:

As I said above, tomorrow is the first snow map and official forecast. But as a snow lover, I like where today’s trends have gone. I’m probably leaning towards more of a GFS solution for the heaviest snow axis through NJ but I will need through tomorrow around 1pm to confirm that when we make the snow map and issue the forecast. The January 22-24 period is starting to look like a decent winter storm signal but I won’t touch the details of it until this first system slides through.

I will say that the Arctic air that will return with this Jan 19 Sunday system (especially Monday-forward) should be the coldest we’ve felt yet (Monday-Wednesday). You can trace this air mass back to Siberia which has traveled over the N Hemisphere via cross-polar flow (a series of ridges, troughs, highs and lows all perfectly spinning a conveyor belt of the N Hemisphere’s coldest air towards us). I don’t think we’re looking at record cold Monday-Wednesday but certainly dangerous pipe bursting type stuff.

In English: Light snow is falling and will continue to fall until later tonight. Trace-to-light accumulations could slick untreated roads up for this evening’s rush hour commute, especially along WNJ. Please allow some extra time to travel and use caution until the snow ends before midnight. I’m then getting more excited about a snowstorm on Sunday. The Jan 19-21 signal that we originally identified is showing signs of coming to fruition with a robust NJ snow hit this Sunday. It could time poorly with the very important 3pm Eagles game on Sunday but they do play in the snow. How that will affect gameplay is another story but it definitely is starting to look like a snowy game. But for most of NJ, the timing should be between about noon and 9pm Sunday with the heaviest axis of snow likely delivering a plowable snow outcome. We need until tomorrow afternoon to issue a snow map where we think that heaviest axis of snow will be (Through NNJ? Through CNJ? Through SNJ?). But yeah, we’re closing in it actually happening. Very cold air then moves in for Monday-Wednesday with another wintry storm signal showing for Jan 22-24 (to be ironed out). Have a great rest of your Thursday and please be safe! JC

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