Quick update on NJ’s Friday night snowy, icy, rainy mess

UPDATE... This article is outdated...

For the latest storm forecast information, please refer to my newest weather blog post.

UPDATE as of 1:45 p.m. Thursday...

Winter storm warnings and winter weather advisories have been issued for most of New Jersey starting Friday afternoon/evening. The article below has been updated to reflect the latest information from the National Weather Service.

ORIGINAL POST from 12:32 p.m. Thursday...

Merry Christmas to all! For those who celebrate, I hope your Christmas morning was as magical as my family's!

Now, we do have some business to handle, with winter weather on the horizon. First flakes are now a little more than 24 hours away, so it is time to get serious about nailing down storm timeline, accumulations, and potential hazards. Especially given the post-holiday timing and busy travel week (by road, rail, and air), this is a forecast we all need to watch carefully.

Before the Storm

Weather in a word for Christmas Day: OK. Just OK. Skies are pretty cloudy to start the day, and we are seeing some spotty rain showers passing through New Jersey too. Temperatures are in the 40s, so there is no risk of icy spots. (Unfortunately no chance of magical Christmas snowflakes falling from the sky either.)

Thursday night will stay quiet and quite cold. Low temperatures will dip into the mid 20s for most. The coldest corners of New Jersey will likely dip into the teens by Friday morning.

Timeline

Right off the bat, I want to stress: Most of the daytime hours on Friday will be fine. The worst wintry conditions won't come until nighttime.

The morning will be cloudy. Along with a colder air mass, high temperatures will not climb beyond the lower-mid 30s. Of course, cold air is the first ingredient for snow and ice, so the chill in the air should not come as a surprise.

There is a chance for initial showers to push into NW NJ Friday afternoon, as early as 1 or 2 o'clock. However, this feels early to me, given the full spread of current model guidance. Anything that does fall from the sky in the afternoon hours will be light and scattered — I do not think we are looking at any widespread accumulations or travel concerns just yet. So I maintain the timeline that roads will remain (mainly) clear and passable through at least sunset Friday afternoon.

Then things go downhill. Precipitation will spread throughout New Jersey from the late afternoon to early evening hours, around dinnertime. For approximately the northern half of the state, this is likely to be straight snow at the onset. Farther south, precipitation type is more unclear — there could be some snow, but more likely there will be some sleet or rain mixed in. (This is largely dependent on the exact temperatures, which is largely dependent on the exact track of the parent clipper storm system.)

The brunt of the storm will be mid to late Friday evening, around 8 p.m. to Midnight. This is where you need to hunker down, as pockets of steady to heavy snow and sleet (more of an icy sleet/rain mix to the south) make for increasingly slick roads and perilously low visibility. The fastest snow accumulations will also happen during this time frame, for northern and central New Jersey. (More on forecast snowfall totals in a moment.)

Beyond Midnight, precipitation intensity will slowly dial back through daybreak Saturday. For most of the state, temperatures both at the surface and aloft will teeter right on the line between straight snow and icy mix. Travel conditions will likely remain poor until right around sunrise.

Spotty snow and rain showers will likely linger through about midday on Saturday. Additional accumulation is unlikely at this time, but the weather will feel unsettled. Some models keep snowflakes and raindrops along the eastern edge of New Jersey into the afternoon — a possibility we should keep in mind.

High temperatures on Saturday will only be in the 30s. Hopefully we will catch some partial sunshine in the afternoon, which would help with snow and ice melt. I would expect most accumulated snow to stick around through the weekend.

Accumulations

For approximately the northern half of New Jersey — from Mercer and Monmouth counties to the top — snow will stick and accumulate quickly Friday night.

Having said that, there remains some uncertainty here in exactly where the heaviest snow bands will set up, how prolonged and heavy they will be, and (most importantly) how much sleet will mix in. (Sleet, or ice pellets, does not accumulate nearly as quickly or efficiently as snow.)

I am holding steady on a forecast of 4 to 8 inches for this "snow zone bullseye" of northern New Jersey. In my last post, I also called this "about 6 inches" and said "10 inches is possible somewhere". Both are still true, but I think 4 to 8 more accurately represents the low-side and high-side snowfall potential as I currently see it. (Overall, I am much more worried about forecast underperformance than overperformance this time around, especially given the sleet mixing potential.)

Farther south, this forecast call gets even more complicated. Between approximately I-195 and the Atlantic City Expressway, I think we will see some snow accumulation, on the order of 2 to 4 inches. Lighter snow bands and more of an icy mix (mainly sleet) in general will limit totals. Even so, I would call the wintry impacts in this area "moderate" and certainly enough to cause a period of treacherous travel during and after the brunt of the storm.

Far South Jersey, this looks like mainly a rainmaker for you. However, there will be opportunities for wintry precipitation (mainly an icy mix) falling from the sky and slick spots on the roads. I'm calling it "0 to 2 inches" of snow accumulation, as I do not think you will need the shovel and/or snowblower this time around. A glaze of ice is a possibility here too, especially along the western edge of the state (Delaware River).

(For the record, I was tempted to highlight the southern coast counties of Atlantic, Cape May, and Cumberland on my forecast map as being the most likely to get no snow stickage at all. But all it would take is for temperatures to trend a few degrees colder, and there could be a coating. So worth including in the "0 to 2 inches" band, just in case.)

Alerts / Impacts

A Winter Storm Warning has been issued (upgraded from the previous Watch) for 8 counties in northern New Jersey. This pinpoints the area most likely to see at least 5 or 6 inches of total snow accumulation. Travel in this area will become very dangerous or even impossible at times.
—From 1 p.m. Friday to 10 a.m. Saturday... Morris, Sussex, and Warren counties.
—From 4 p.m. Friday to 1 p.m. Saturday... Bergen, Essex, Hudson, Passaic, and Union counties.

Additionally, a less-severe, less-urgent Winter Weather Advisory covers an additional 11 counties through central and southern New Jersey. Advisories are issued not only for a few inches of snowfall, but also for the possibility of light icing. Again, travel by car is the biggest concern here due to slippery roads and/or low visibility.
—From 3 p.m. Friday to 10 a.m. Saturday... Burlington, Camden, Cumberland, Gloucester, Hunterdon, Mercer, Middlesex, Monmouth, Ocean, Salem, and Somerset.

No official advisories or warnings have been issued for Atlantic or Cape May counties, for now.

After the Storm

Sunday stays chilly, with highs again only in the 30s. But at least we will see partial sunshine and light winds.

A front moves in Sunday night. Accompanied initially by warming temperatures, this one looks like a quick rainmaker for New Jersey. Maybe a little bit of wintry mix among the colder northwest hills. But for the vast majority of the state, just wet. Gusty winds are a possibility too.

Behind the front, temperatures crash again, as we enter a period of cold, dry, but quiet weather. I do not foresee any more substantial snow chances until the new year.

What's Next?

As soon as the Christmas holiday is over, we will shift directly into storm mode operations. Expect one more weather blog forecast update early Friday morning, followed by regular on-air and online updates throughout the day as the storm approaches.

Our weather, traffic, and talk teams are ready to go for Winter Weather Alert coverage both Friday evening and Saturday morning. Despite the weird "holiday week" timing of this storm, we are here to keep you informed and safe for the duration.

Dan Zarrow is Chief Meteorologist for Townsquare Media New Jersey. Follow him on Facebook for the latest forecast and realtime weather updates.