More snow Sunday night

  • Significant snowfall expected Sunday evening and night for northern, central New Jersey
  • Accumulating snow begins between 4 and 6 p.m., ends after midnight
  • Up to 8 inches in parts of the state, mostly rain south
  • Update: Gov. Phil Murphy declared a state of emergency effective 3 p.m. Sunday

With accumulating snow later Sunday afternoon and evening, many parts of the state will be seeing their fourth accumulating snow event in the last five days. The system Sunday is the most robust of the series of storms, and significant snowfall will be the most widespread. Similar to the Friday night/Saturday morning event, this storm will bring a winter weather impact to the northern half of the state, and southern New Jersey will see mostly rain.

A weak, flat, progressive mid-level wave is racing across the southern tier of the country. Embedded within the Pacific jet stream, the wave has plenty of moisture to work with. Meanwhile, strong high pressure and Arctic cold is pressing south into the upper Midwest and Great Lakes. A surface low is coalescing over the Gulf states, and will slide northeast into the Atlantic Ocean off the Outer Banks Sunday night. Low and mid-level forcing and favorable upper-level jet venting will encourage precipitation to blossom up the eastern seaboard late this afternoon, with a period of moderate to heavy snow overnight before the low strengthens well to our east, out to sea.

It’s mild out Sunday, not a single station in New Jersey is below freezing as of late morning. However, dew points are falling, and as moisture advects into the northern mid-Atlantic, clouds will thicken and temperatures will quickly fall below or near freezing at the surface on a line from Philadelphia through Monmouth County. Precipitation will begin between 3 and 5 p.m. for everyone. Everyone could begin as rain showers, but a quick change to snow is expected north and west of Route 1. Gradually, a change to snow will occur through the Turnpike corridor as well. I don’t think this is much of a winter weather event east of the Turnpike and south of 195, except for northern Burlington and western Monmouth Counties.

Once the rain/snow line is established, I don’t expect it to move much for the six hour period in which the heaviest snow falls, which is roughly 7 p.m. to 1 a.m.. If you’re snowing at 7 p.m., you’re going to wake up to significant accumulation. If it’s rain or a wintry mix, you’ll see nothing or the lower end of accumulation possibilities. Warm pushes at the surface and the mid-levels will hit a wall as the Arctic high presses into the northern mid-Atlantic during the later stages of the event. The storm also doesn’t really develop and intensify until it’s off the coast, further limiting the typical warm air surge.

The battleground will be the 95 corridor and the suburbs of the cities. As always, subtle changes in storm track of 15 to 20 miles will be the difference between 5 to 6 inches of snow, or nothing, for millions of people. I think the cities get in on the action, but the best accumulations will be to the north and west of Route 1.

If you need to be out Sunday night, there will be a band of snow with very heavy rates, perhaps approaching 2 inches an hour somewhere in central New Jersey. Most likely it will be just to the north and west of the rain/snow line in northern Mercer, Middlesex, Somerset, Union, and Hudson. Residents on the roads under that band will be in for a really difficult ride. Luckily we’re talking about Sunday night, probably the least trafficked time of the week. Expect 6 to 8″ inches if you’re under this band, and a little less outside it. The transition zone over the 95 corridor will see less, with poor snow to liquid ratios, and some sleet or rain at the end. Further south, after a coating to an inch or so, plain rain will be the dominant precipitation type.

The system is another quick hitter and it’s long gone by daybreak. There will be plenty to clean up for many, and then the focus will shift from wintry precipitation to wintry temperatures. Arctic cold builds in with high pressure on the back side of the departing storm. Overnight lows Monday, Tuesday, and Wednesday nights will be in the mid teens to low twenties. Daytime highs will stay below freezing for most. Another weak system could bring light rain or snow showers at the end of the week. That might be it for wintry weather this season, as some spring weather is in the offing thereafter.