NJ weather about to turn wintry – 0-3″ Thu-Fri, 0-12″ Sat-Sun
UPDATE as of 6:45 p.m. Wednesday
We're starting to lock-in the timing and potential totals for the Thursday night-Friday storm. But the weekend snow/ice/rain storm is still very complicated and delicate. I just published a fresh weather blog entry with the very latest insight on what we know and what we don't.
ORIGINAL POST from 7:33 a.m. Wednesday
Our weather forecast is a one-two-three punch of active, wintry weather. Storm system #1 will arrive Thursday night through early Friday, with snow changing to rain. Storm system #2 is bigger and stronger, with impacts from Saturday evening through Sunday night. And the third upcoming weather hit is a blast of ridiculously cold air coming behind these two storms from Sunday into Monday.
Quiet for Now
I like "normal" weather. When temperatures are close to seasonal average for a given time of year, there's not much to complain about. That will be the case Wednesday, with morning lows in the lower 20s and afternoon highs in the lower 40s. The day will start with beautiful blue skies and sunshine, with some cloudiness later on. A noticeable breeze will blow out of the southwest up to about 20 mph.
A weak cold front will pass through New Jersey Wednesday evening. It's going to be a mostly dry event, although an isolated snow shower (more like flurries) is possible. There will be a few clouds overhead, but skies will be just clear enough to allow temperatures to tank. We'll end up in the lower 20s yet again by Thursday morning.
And the daytime hours on Thursday still look quiet. Skies will be mostly cloudy, and temperatures will be cooler with high temps limited to the lower to mid 30s.
Storm #1: Snow to Rain
Well after the Thursday evening rush hour ends — around 9 p.m. — first snowflakes will arrive in western New Jersey. After Midnight, bands of light to moderate snow will continue. However, temperatures will slowly rise during the overnight hours, forcing a transition from snow to straight rain.
The first spot to change over to all rain will be the immediate coast, around Midnight Friday morning. By the start of the Friday morning rush hour (5 a.m.), the snow-rain line should have reached as far north as Middlesex and Mercer counties — points south of that will be rain/mix, points north of that will be snow. Until precipitation tapers off completely midday, the transition will continue to drive northward.
The biggest snow accumulations will be found in northwestern New Jersey, where snow (and only snow) will fall for a good 12 hours. Up to 3 inches of accumulation is possible in that corner of the state. Along the Turnpike corridor, we're looking at a slushy inch on the ground at some point. Closer to the coast, little to no accumulation of snow and ice is expected.
It is worth mentioning that the NAM model paints a colder scenario for Thursday night and Friday, which would produce a longer period of widespread snow with less (or even no) mixing/rain. I don't think that would lead to a dramatic increase in snow accumulations, however, as the intensity of that snow looks to stay light and scattered.
My biggest concern? Friday morning's commute. While this won't be a major winter storm, driving conditions could get pretty sloppy. Especially where roads are snow-covered (NW) or slushy (away from the coast).
Skies will partially clear Friday afternoon, with temperatures rising into the lower to mid 40s. Not bad.
Storm #2: Snow to Rain/Ice to Snow
As we've discussed all week, the second storm in the queue is bigger, stronger, and far more complicated. This is still a constantly evolving situation, that is going to involve a number of potential weather hazards.
It's becoming clear that the "meat" of this storm system, with the heaviest snow and biggest impacts, will pass north of New Jersey. You want over a foot of snow, like some of our local media is hyping? Drive to New England.
That puts the Garden State in a precarious position, with wildly swinging temperatures forcing a transition from snow to rain to ice to snow. Confidence is still very shaky, but here's how I see this system playing out.
Initial precipitation arrives Saturday evening, around 6 p.m. It will be a quick burst of moderate to heavy snow for most of the state, with above-freezing temperatures potentially allowing for just rain along the southern coast. Just like Storm #1, a transition from wintry to wet will take place Saturday night into Sunday morning. Temperatures as you wake up Sunday morning will range from the lower 30s (north) to lower 50s (south). By that point, it's going to be almost all raindrops falling from the sky.
However, I have a concern about significant icing due to freezing rain, especially in North Jersey. Remember: freezing rain looks like rain, sounds like rain, smells and tastes like rain. But as soon as those droplets hit a subfreezing surface, they freeze to solid ice on contact. Such an "ice storm" creates a far more slippery situation than just a "snow storm". And it doesn't take much ice to wreak havoc on the roads and bring down trees and power lines.
At some point on Sunday, temperatures will fall sharply, enacting a shift back to mostly snow across New Jersey. Precipitation will most likely taper off Sunday afternoon, but the storm may linger through late evening.
I am not ready to produce a snow accumulation map for this system, as there are so many variables still in question. How intense will the snow be? When will it make the transition, if it even does? How intense will the rain be? How will freezing rain and sleet contribute to a potential icing situation? When will rain change back to snow? How intense will that batch of snowfall get? Where will the overall dividing line between between "mostly snow" and "mostly rain" end up?
Just to give you an idea of magnitude, if it stays cold enough and if there's not too much icing going on, I'm thinking snowfall in NW NJ could range from 6 to 12 inches. On the other hand, SE NJ is looking at 0 to maybe 4 inches of snow accumulation. (That's on top of 1.5 to 2 inches of total rainfall.) How tight is that gradient of "boom" to "bust" going to be, and what is going to happen down the middle of the state? Who knows, it could swing either way at this point.
Of course, there's still a significant margin of error with this forecast too. If we swing much colder, more of the state will be prone to see healthy, potentially heavy snowfall. If temperatures swing warmer, snow accumulations will be limited.
One important development in this stormy forecast is the bitter arctic air that will get dragged down behind this weekend's winter storm. Yes, it's time for our friend the polar vortex to visit the NE United States.
First of all, the nosediving temperatures on Sunday could cause an incredibly hazardous situation across the state called a flash freeze. As thermometers rapidly drop well below the freezing mark, wet surfaces could ice over in a matter of minutes — yes, it's going to get that cold that quickly! I remember a particular flash freeze in February 2015 that caused a dramatic 40-car pileup on the NJ Turnpike. So even after the snow-mix-rain ends, we'll still have to be vigilant for slippery conditions Sunday night.
Second, Monday is going to be ridiculously cold. We're talking about potentially dangerous cold. Monday morning's low temperatures are forecast to dip into the single digits across most of the state. And, with the continuation of a brisk northwesterly wind, the wind chill could reach about -10 degrees. Yes, that's a minus. High temperatures will only reach about 20 degrees. Monday could easily be New Jersey's coldest day in over a year (January 5-7, 2018).
By the way, the next next next storm system is showing up in the models for next Tuesday to Wednesday. We'll talk more about that when the time is right.