Update on Monday night’s messy, potentially icy forecast
For the first time this winter, snow and ice will be possible in the Garden State, although most of the state will likely be limited to a cold rain.
UPDATE... At 3:20 p.m. on Sunday, the National Weather Service issued a Winter Weather Advisory for Sussex, Warren, Morris, and northern Passaic counties in North Jersey, from Monday night through Tuesday morning. It's NOT a warning - an advisory means that a combination of freezing rain, sleet, and snow may lead to slippery roads and reduced visibility at times.
This is an update to yesterday's post about a minor winter weather threat headed for New Jersey from Monday night through early Tuesday morning. There are no big changes to the going forecast, but the overall picture is becoming clearer, so we can start to put some additional detail on this potentially messy forecast.
The Storm's Progression
At the moment, the system we're watching is a very powerful winter storm that has brought tornadoes, blizzard conditions, and flooding to the Southern Plains states. As this low pressure system pushes to the northeast, it will bring snow to the Central Plains, Midwest, and Great Lakes regions before setting sights on the Northeast U.S.
Winter weather forecasting can be incredibly challenging, as there are many weather ingredients that factor in to storm timing, snow accumulations, whether icing will be a major issue, etc. Sometimes the difference between getting several inches of snow and nothing at all can be a matter of a few degrees or a few miles. Luckily, the computer models we use to forecast the weather are in pretty good agreement over this storm. (The big difference in this afternoon's model output is that the NAM model pushes rain over New Jersey for much of Monday, while the GFS keeps us fairly dry until Monday evening.)
The NAM, GFS, and Euro all agree where it counts, though - temperatures will likely fall into the upper 20s to lower 30s for the northern third of New Jersey for a few hours between Monday night and early Tuesday morning. That's cold enough to warrant some icing concerns, especially in the higher elevations along and north of Interstate 80.
We maintain, however that snow totals will be light, ice issues will be limited in time and geography, and most of New Jersey will just plain rain from this storm.
There are several reasons why New Jersey will NOT see big wintry impacts from this storm...
1.) We are only getting clipped by the system, which is tracking well to the north of New Jersey. Heavy snow - over 10 inches in spots - will be possible from the northern Catskills through the Adirondacks in northern New York and Canada.
2.) Our ground is still incredibly warm across most of New Jersey - still measuring 50 degrees in many spots. That means accumulation of snow and/or ice will be difficult, but not impossible. Bridges, overpasses, on-ramps, and off-ramps will be most susceptible to icing, as cold air surrounds these structures causing the surface temperature to fall below 32 degrees faster than ground-level asphalt, concrete, grass, and so on. Additionally, the rocky soils of the Sussex County area freezes faster than moisture-rich soil further south in the south.
3.) Surface air temperatures will only fall below freezing for 6 to 8 hours from Monday night through Tuesday morning. Those freezing temperatures will likely be limited to North Jersey.
4.) A warm front will eventually deliver an injection of warmer air. If the warm air arrives Monday night, there will be very little wintry precipitation in New Jersey. If the front comes later, any snow, sleet, and/or freezing rain will quickly transition to all rain.
The Bottom Line
As you know, it has been an unusually warm winter so far. This storm is only significant because it presents the first chance for accumulating snow and ice, and our first potential travel concerns of the winter season.
Along and north of Interstate 80, light snow accumulations will be possible (maybe up to 2 inches at the highest elevations). Icing is probably the more significant concern here as it won't take much ice on an untreated roadway surface to create incredibly slick conditions. Any falling snow and ice will quickly transition to rain as warmer air arrives, while any snow and ice on the ground will quickly melt and/or wash away.
Meanwhile, the area from I-80 down to around the Raritan River (Middlesex/Somerset counties) could see some light snow falling overnight, and maybe patches of ice on Tuesday morning. The precipitation type here, however, will be mostly rain.
From Mercer and Monmouth counties southward, only rain is expected from this system.
I repeat once again... This is not going to be a big winter storm for New Jersey. This is not a "bread and milk" kind of storm. It would be a good idea to continue monitoring this evolving forecast and changing weather conditions, especially if your morning commute takes you anywhere near North Jersey (or points further north) on Tuesday.