By Meteorologist John Cifelli
Our winter storm system is creeping up the eastern seaboard right this very moment, poised to affect New Jersey shortly after the evening commute, and into tomorrow. This will be the first widespread storm of 2015 that will affect the entire state with wintry weather, although you will experience very different conditions depending on where in the state you over the next 24 to 36 hours.
It looks like a mixed bag of precipitation, and a rather tricky forecast. Nor’easters, as this storm is, always draw a battle zone between warm and cold air that manifests itself as the rain snow line. Typically, this line tends to be along I-95, where the flat, coastal plain is divided from the rising elevations of the northern and western part of the state. As the coastal storm moves from the Virginia maritimes to just off the coast of Atlantic City, the warm air intrusion will overspread New Jersey, changing precipitation from snow to sleet, rain and freezing rain. The devil in these details is trying to figure out what level of the atmosphere will see warming above freezing first. Right now I am thinking that for those a fair distance away from the coast, warming above freezing arrives aloft before it does at the surface. That spells freezing rain, which of course makes for the worst driving conditions.
Shortly after rush hour tonight, snow begins in southern New Jersey. Even here we will see accumulation except far southern coastal areas, before a changeover to plain rain. By midnight, precipitation will be at the doorstep of New York City and northern New Jersey. It will come in like a wall, going from nothing to moderate snow with poor visibility quickly. Roads will deteriorate, so cut your after work revelry a little short this evening and get home safe.
By the time we wake up, the transition zone will be working its way through the Route 1 corridor and headed north. This is where the forecast becomes difficult. If the surface is 31 degrees and it’s raining, we’re dealing with freezing rain. If it’s 33 degrees, it’s plain rain. These situations are very marginal but can be very dangerous. I think the big cities are going to see some light icing for a period in the morning. I think there can be more significant icing just north and west, from the northwest suburbs of Philadelphia, through Bucks County and along the 202 corridor up into northern Manhattan and eastern New Jersey. The saving grace in this case would be two fold — ice on top of snow that has already fallen causes fewer issues, and this is occurring on a weekend without a work commute. Further north, expect a snowier scenario, particularly once you get north of 80.
The surface low will be in position under some impressive upper level jet streaks by late Saturday morning, south of Long Island. This will cause rapid strengthening as it starts to pull away. As a result, precipitation may end as snow showers everywhere north of 195. As that deepening of the surface low occurs, there is the chance that a quick band of heavier snow could move through northern areas and New York City, putting down an extra inch or so in the early afternoon. By late afternoon and early evening the skies will clear, but we will quickly drop below freezing after sunset, so what is not already frozen, will be. It will be slow going for much of the state until Sunday morning.
Sunday night’s light snow looks to be focused on the southern half of the state for now.