Tracking Snow this Week-Weekend

Discussion: We’re going to switch into daily article mode this week (rather than a single weekly outlook) as there is a lot going on.

First let’s talk about the current state of things. There’s all sorts of stratospheric warming and polar vortex elongation happening which so far, is producing a December of below-average temperatures for New Jersey. The polar jet stream is currently somewhat locked into a pattern of rushing southward into the Montana area of the NW US, extending down into the MidWest US, and then over (eastward) to the Mid-Atlantic. Everyone to the N and E of this jet stream is cold and everyone S and W of it is mild. For NJ, we are on the colder side for now. This jet stream acts as a highway for lows to follow (more or less the thermal gradient boundary), which in this configuration means a stream of clippers. You sometimes hear them referred to as Alberta Clippers given their typical Alberta, Canada origin but sometimes they come out of Saskatchewan or other nearby Canadian provinces. Either way clippers are typically colder and moisture-starved systems which produce high-ratio (fine dusty flakes) snowfall anywhere in the range of a coating to a few inches. However, sometimes they couple with energy off the warmer subtropical jet stream as they approach the E US coast which allows them to become something more. What we lack in this pattern is blocking over Greenland which slows the systems down into a massive snowstorm. Instead, we have a progressive flow pattern where systems approach from the W and pass through relatively quickly. You can still get larger snowfalls out of this setup if there’s a proper coupling of energy AND the thermal gradient is adjusted to proper latitude (the boundary). And that’s what I’m looking for later this weekend. But before we talk about later this weekend, let’s talk about this week.

Today (Monday) is obviously on the colder side. A snow system hit Virginia/SC Mid-Atlantic US today with a few inches of snow with NJ just on the N dry side of it. The further S in NJ you are, the more you can almost feel and smell it today. As this wave departs from the E US, it will pull even colder air down behind it making for a cold Monday night into Tuesday. As it stands right now, midday Monday, the high temperatures are at or below freezing statewide with dew points in the single digits/teens. By sunrise Tuesday morning, I’m expecting NJ low temps to range from 5-20 NNJ elevations to SNJ coasts with most of the state easily falling into the teens.

Tuesday NJ highs should range from 27-35 NNJ to SNJ. Another cold day for this time of year but we’re dry with N winds. Temps should kind of hold heading into Tuesday night/Wednesday morning as another wave approaches with milder air ahead of it trying to fight the overnight low temp drop. Then on Wednesday, the coastal plain and piedmont warms up to the 35-40 range as precipitation approaches. I expect rain for these areas but N of I-78 and NW of I-287 is looking wintry with a few inches of snow possible for higher elevations and at least a wintry mix for low-mid elevations. Then behind the Wednesday wave, temps crash again for Thursday into the weekend. Saturday should warm up a little on the coastal plain again (to about 40) and then we drop for Sunday’s potential snow that could fall statewide.

The later-weekend snow potential has evolved from two different waves. One was looking like Dec 11-13 and the other Dec 14-15. Last week, it looked like at least one of these waves would try to hit NJ depending on which one had a better interaction with southern moisture. Over the last 48-72 hours, it has become apparent that the second wave has become favored. Today (Monday) has exactly what I wanted to see on model guidance for the snow possibility which is agreement on the signal from the GFS, Euro and Canadian operational models. We are still 6 days away but the current time target for the system is between late Saturday night and late Sunday night. Still need a day or two more of interested tracking. If it continues to come together/is still showing Wednesday, it will be time to track seriously.

It would then theoretically become very cold to start next week (in the wake of the snow system)…like highs near-20 lows in the single digits. I am very much interested in how December is going to shake out vs it’s climatological average. I can’t remember a December starting this cold in quite a while.

So as each of these clipper waves pass through, they pull mild air up in front of them and pull colder air down behind them. In their wake, they leave a thermal gradient boundary which becomes the highway for the next approaching system to track along. Today’s wave missed to the S of NJ. Wednesday’s will miss to the N of NJ (clipping NWNJ). Sunday might just hit perfect with some additional southern moisture feeding it and making it more than just a clipper. Again, that’s what I’m watching for and will report on accordingly. We’ll likely have snow maps out soon for Wednesday’s wave (primarily affecting NWNJ).

In English: Expect a cold Monday night into Tuesday morning as a snow wave missed just to the S of NJ today (Monday). It will pull cold air down behind it and make it feel like mid-January tonight (Monday night) through Tuesday and Tuesday evening. Tuesday highs likely at or below freezing for most NJ areas (less immediate SENJ coast) but dry. Wednesday looks like snow for NWNJ, a mix down into parts of NENJ/WCNJ and a cold rain for the rest of NJ S of I-78/SE of I-287 as another wave comes through that’s a little too far N for a statewide snow.  This Wednesday wave will also pull cold air down behind it as Thursday-Saturday looks like more cold and dry conditions. Then late Saturday night/Sunday morning we could see a statewide snowfall begin and last through Sunday evening which I’ll be discussing more this week as we approach closer. A mostly wintry week ahead with more info to come. Be safe! JC

Premium Services

KABOOM Club offers ad-free content, inside info forecast discussion, your questions answered, and early storm impact maps and video releases (ahead of the public). At $1.99 per month, it’s an extremely feasible way to show additional support for Weather NJ and you can turn it on and off for however many months you wish. Think of it as a tip jar with perks. Available on Facebook or Patreon. 

My Pocket Meteorologist (MPM), in partnership with EPAWA Weather Consulting, offers professional/commercial interests, whose businesses depend on outdoor weather conditions (snow plowing, landscaping, construction, etc.), with hyper-local text message alerts/forecasts from real meteorologists and access to the MPM premium forum—the most comprehensive and technical forecast discussion available for PA and NJ.

KABOOM Shop is live if you want some KABOOM or Weather NJ Merch!