Wild weekend weather for NJ: Cold, snow, ice, rain, wind, flooding
UPDATE... This article is outdated...
For the latest winter storm forecast information, please refer to my newest weather blog post.
UPDATE as of 2:45 p.m. Friday...
Afternoon models are in. I am not going to issue a full forecast update until tomorrow morning, but here are some bullet points for those interested in the wild weekend outlook.
—Cold air has started to leak into NJ. It's already breezy, and temperatures will really tank after sunset.
—Bitterly cold tomorrow. AM wind chills near zero. High temps only lower 20s. #BundleUp
—The bottom line for Sunday night's powerful storm system remains the same: This will NOT be a 'snow' storm for most (if not all) of New Jersey.
—The map I drew Friday morning still looks right on. (See below.) "Mainly Snow" to the NW, "Snow to Mix to Rain" along the Turnpike corridor, "Almost All Rain" near the Jersey Shore.
—No change to timing picture either. Starts late Sunday afternoon, peaks overnight, wraps up early Monday morning.
—The big question that remains... How much snow, slush, ice, and rain will fall and accumulate? I threw out some rough numbers this morning, but I have little confidence in them.
—Let's not ignore the wind and coastal flooding threats too. It is going to be a nasty storm.
ORIGINAL POST from 9:59 a.m. Friday...
The Bottom Line
I think I hit all the major weather concerns in the headline. And all that mess covers the forecast for only the next four days.
There are really two storm systems at play here. First is another strong cold front, arriving Friday afternoon. It will not produce any precipitation over New Jersey, but it will drive in an arctic wind, causing temperatures to tumble. Saturday is going to be unseasonably, uncomfortable, and even dangerously cold.
Then our attention turns to a storm coastal storm system — a (Miller Type A) nor'easter — this weekend. Specifically, that strong area of low pressure is forecast to pass directly over New Jersey from Sunday night to Monday morning. We're starting to get more confident resolution on the exact storm track, which will directly dictate what falls from the sky. I'm still thinking it will be a "Turnpike storm," with mainly snow to the northwest, mainly rain to the southeast, and a wintry mess in the middle.
Another Deep Freeze
For the second time this week, arctic air is knocking on New Jersey's door. Friday is starting off OK - mostly cloudy, light winds, high temperatures in the 40s. But things will go downhill starting in the afternoon.
You'll know immediately when that front arrives. A north wind will kick up, gusting to about 30 mph. Skies will clear to sunshine (as drier air arrives). And, of course, temperatures will start to nosedive. Thermometers will go from the 40s around lunch Friday, to below-freezing by dinner, to the teens by breakfast Saturday.
High temperatures on Saturday are forecast to only reach the lower 20s, give or take. That is 15 to 20 degrees below normal for mid-January.
The combination of cold and wind will push the wind chill (the "feels like" or "apparent" temperature) to about zero early Saturday morning. And, even though the wind will calm on Saturday, the wind chill will struggle to get past the lower teens. Bundle the heck up.
A Wind Chill Advisory has been issued for Sussex County only, from 10 p.m. Friday through 10 a.m. Saturday. Wind chills may dip as low as -20. That is dangerous cold.
Oddly enough, Saturday's frigid temperatures will have little impact on our impending nor'easter. Yes, the ground will be cold enough for snow to stick immediately (where it does snow). But because of the influx of warmer air, southeastern New Jersey will go from subfreezing 20s (at best) on Saturday to just plain rain 24 hours later.
On Thursday, I posited four different track scenarios our big storm system could take. Four "roads" that would lead to four very different outcomes. To refresh your memory, they are:
1.) West of NJ: Mainly rain
2.) Directly over NJ: Wintry mess, snow to rain
3.) Just east of NJ: Snow bomb
4.) Far east of NJ: Total miss
I think we can safely remove #4, the complete miss, from the table at this point. In other words, we're highly confident now that New Jersey will feel significant impacts from this storm.
At the same time, I'm still leaning heavily toward #2. Not all snow, not all rain, but a little bit of both.
Even though the latest model guidance nudges the storm's center east slightly, I fully expected that. It's not enough of an off-shore track to justify a snowy forecast for all of New Jersey. In fact, the latest data suggests everyone warms into "the mixing zone" by the time the storm wraps up.
It's important to note that the proximity of the low pressure center will lead to heavier precipitation overall, in addition to a serious wind threat. (We'll talk about that in a second.)
Timing: Locked In
Most of Sunday's daytime hours will be fine and storm-free. Temperatures will even moderate into the 30s by the afternoon.
We'll be watching for "first flakes" to push into southwestern New Jersey around 3 p.m. Sunday. Precipitation will envelop the entire state by around 8 p.m. Sunday.
The heaviest snow/ice/rain will occur overnight, between about 8 p.m. Sunday and 4 a.m. Monday.
The storm should wind down quickly around daybreak Monday. Lingering showers and gusty winds may continue into the afternoon.
Rain, Ice, Snow?
An important element of this storm forecast is rising temperatures throughout the night. So the best chance for wintry precipitation will be at onset, Sunday evening. And the snowiest part of the state will be the coldest corner, to the northwest. The speed of that temperature rise, coupled with the timing of the brunt of the storm, will dictate how much snow is able to stick and accumulate.
I think the impacts map I created tells the story well.
In North Jersey, it will be a snowy night. At the moment, I've put a 3-6" snow contour approximately north of Interstate 78 and west of the Garden State Parkway. If the storm track and forecast precipitation stays on track, I could see the need to bump that even higher. On the other hand, any little bit of mixing at any point will quash bigger snow totals.
To the south and along the coast, it will be a (mostly) rainy night. Although you might see some snow, sleet, and/or freezing rain at onset, it won't take long to transition to a cold, uncomfortable rain. (Actually, some models have pushed the idea of 50-degree temperatures - that's really not that cold!) Over an inch of total rainfall seems to be a good bet for the coastal plain.
The middle of the state - approximately on either side of the NJ Turnpike corridor - is the big challenge here. You will likely undergo a transition from all snow, to a wintry mix, to all rain. Whether roads become snowy, slushy, icy, or wet depends on the timing of that transition. That's why I've painted a broad 0-3" accumulation for this sector, which I expect to refine further in future forecasts.
Don't pay too much attention to the numbers, but rather the general impacts I've painted here. The storm's track is still very much subject to wiggle, and that can have a dramatic effect on how many snowflakes fall in each sector of New Jersey. I promise our storm outline will get more specific and more actionable as the storm draws closer.
Other Impacts: Wind & Coastal Flooding
Adding to the nastiness of this winter storm will be a gusty wind, blowing out of the east-northeast for a majority of the storm. 40 mph gusts inland and 50+ mph gusts along the coast could cause some power outages. Visibility may be reduced during snowfall and rainfall. And, in the cold zone, it would make for some bitter wind chills.
Furthermore, that easterly wind is an on-shore wind. That causes our ears to prick up for the threat of tidal flooding along the Jersey Shore.
Tidal guidance only goes out 72 hours, so we're just starting to get a taste of the magnitude here. The worst surge estimates are coming in between 2 and 4 feet, enough to breach moderate flood stage at high tide. That is admittedly a rough, low confidence estimate for now. As we lock in the timing and orientation of the strongest winds, we'll have a better idea of how high tidal waterways could run. Clearly it's an impact we can not ignore.
From cold to snow to ice to rain to wind to coastal flooding, this weekend is going to feature some wild weather. I highly recommend you stay updated with the latest forecast, so you can make informed decisions to stay safe and warm and comfortable.
Unless the forecast changes dramatically, I likely won't publish an update until mid-morning Saturday. We'll then be able to talk about more specifics and more details, and we'll start looking for advisories, watches, and warnings to be issued through Saturday afternoon.