Winter Storm Warning: Snow-ice-rain hour-by-hour forecast for NJ
When it comes to winter storms in New Jersey, it's never easy.
Seriously, I often muse about how unique and complicated New Jersey's weather and climate is. That is in large part due to the interplay of an ocean to the southeast, mountains to the northwest, several urban areas, and a giant forecast smack dab in the middle. I think it's fair to say that our little state sees the most impressive meteorological diversity during the winter, and Tuesday's storm will be no exception.
Our next taste of winter ramps up Monday night and Governor Murphy has announced a State of Emergency beginning at Midnight. (Just a reminder, all an SOE does is make money, manpower, and machinery available to emergency management personnel. As of this writing, no travel ban nor statewide closures have been ordered.)
I just wanted to update you on the latest snow/ice forecast for the storm, our latest warnings and advisories, and walk you through the storm's expected timeline hour-by-hour (well, 3-hour by 3-hour).
The Latest Forecast
Here is the snow and ice accumulation forecast. It is the exact same map I posted Monday morning, with one exception: I lowered the green contour in southern NJ from Coating to 2" to Coating to 1". (The previously higher forecast also included lingering snow that fell south of the AC Expressway during the day Monday.)
Snow returns late tonight, after Midnight for much of the Garden State. The heaviest precipitation is expected around mid-morning Tuesday. As temperatures warm, snow will transition to sleet/freezing rain and then all rain, from south to north during the day Tuesday.
The Latest Warnings and Advisories
A Winter Storm Warning (Pink) has been issued for all of part of 6 counties in New Jersey. A "warning" means a half-foot of snow and a significant glaze of ice are possible. School closings are likely.
—6 p.m. Monday to Midnight Wednesday... Hunterdon, Morris, Somerset, and Warren counties.
—Midnight Tuesday to 6 a.m. Wednesday... Sussex County.
—6 a.m. Tuesday to 6 a.m. Wednesday... Western Passaic County.
A Winter Weather Advisory (Purple) has been issued for all or part of 15 counties in New Jersey. An "advisory" means a few inches of snow and light icing are possible. School delays are likely, with closings possible (a "game day decision").
—6 p.m. Monday to 6 p.m. Tuesday... Atlantic, Burlington, Camden, Cumberland, Gloucester, Mercer, Middlesex, Monmouth, Ocean, and Salem counties.
—5 a.m. Tuesday to 6 a.m. Wednesday... Bergen, Essex, Hudson, eastern Passaic, and Union counties.
Nothing (White) is in effect for Cape May County. Even though it's been snowing and raining there all day, hardly any additional snow/ice accumulation is expected before the changeover to rain.
While the general geography of these advisories looks good, I still don't completely agree with the National Weather Service's timing and advertised totals. Please see my forecast map above for a visual depiction of snow and ice accumulations.
The Latest Storm Timeline
In order to illustrate how the storm will play out, I'm going to use the raw (12Z) GFS model output. It's not a perfect representation, but it follows along my forecast thinking very closely. (Specifically, I'm leaning toward a slightly earlier snow-mix-rain transition.)
I think the illustration will help you understand how this complicated transition from snow to ice to rain will play out. (Of course, I've never tried this in my CMDZ Weather Blog before, so I do hope it's helpful!)
On the maps you are about to view: Green is rain, Yellow is heavy rain, Blue is snow, Dark Blue is heavy snow, Red/Salmon is ice pellets (sleet), and Purple/Pink is freezing rain.
1 a.m. Tuesday... As our storm system spreads northward again, snow will spread across the Garden State. Note: it may not start snowing again in central and northern New Jersey until closer to daybreak Tuesday morning.
4 a.m. Tuesday... Light to moderate snow across pretty much the entire state at this point. Transition to rain has begun along the southern coast.
7 a.m. Tuesday... Morning rush hour is underway, and most of the state is still experiencing snow and/or wintry mix. As temperatures continue to warm, rain becomes the predominant precipitation type for South Jersey.
10 a.m. Tuesday... Notice the darker blue, which is heavier snow arriving just as the Tuesday workday begins.
1 p.m. Tuesday... By early afternoon, I believe most of New Jersey will be seeing rain (heavy at times). North Jersey still quite wintry.
4 p.m. Tuesday... It will be a wet and slushy ride home along and south of Interstate 78. But in North Jersey, the threat for ice accumulation continues.
7 p.m. Tuesday... All but the highest elevations in northwestern NJ are seeing rain at this point.
10 p.m. Tuesday... More of the same. Pockets of heavy rain for most of the state, with some continued icing way up north.
1 a.m. Wednesday... Just rain.
4 a.m. Wednesday... Just rain.
7 a.m. Wednesday... Rain starting to taper off, as Wednesday morning's rush hour ramps up. There could be a quick burst of snowflakes at the very tail end of the storm, but additional accumulation is highly unlikely.
10 a.m. Wednesday... Done. A gusty wind to 40 mph will kick up later Wednesday, after the snow-ice-rain comes to an end.
GFS Total Snowfall... This map will look familiar, as it have fallen in line nicely with my previous forecasts. Nearly 0" to the south, nearly 6" to the north. If you want big snow, you have to travel way to the north. (Note: the NAM shows significantly lower snowfall, while the Euro is in general agreement with this GFS solution.)
GFS Total Freezing Rain Accumulation... Freezing rain requires very specific conditions — a shallow pool of subfreezing air right at the surface, with warmer temperatures farther up in the atmosphere. So it's not a guarantee, but icy conditions are very much possible during our transition on Tuesday, potentially leading to a quarter-inch of ice accretion in northern New Jersey.
GFS Total Precipitation... This includes both rain and liquid equivalent of any snow and ice that falls on Tuesday into Wednesday. Over 2 inches of mostly rain in southern New Jersey — that's a lot!
The bottom line that I've been repeating ad nauseam since late last week... No matter what's happening early Tuesday — whether it's snowy, slushy, icy, or just wet — it's going to be a mess.
Remember that the heaviest precipitation doesn't arrive until after about 9 a.m. Tuesday. If you're still at or below freezing at that point, heavy snow and wintry mix is probable (followed by periods of heavy rain in the afternoon).
And finally, it's not just about the snow totals. The icing potential with this storm is pretty significant too. Snow affords you some traction. Freezing rain, sleet, and ice do not.
Set your alarm clock a little early for Tuesday morning. And be prepared to adjust your daily routine to ensure your safety.
I'll be back with you dark n' early Tuesday morning for the storm play-by-play. Next CMDZ weather blog update is expected by 7 a.m. Tuesday.