Winter Storm Warning: Limited snow, significant ice, extreme cold
UPDATE as of 3:30 p.m. Saturday...
First snowflakes have arrived, and we'll see the radar map continue to fill-in through this evening. No big changes to the going forecast — model consensus continues to suggest significant snow and ice will be limited to areas along and north of Interstate 78. It's not a slam dunk though — that's why I've left minor snow and ice chances alive as far south as I-195. The flash freeze is still concerning.
New to the tables are worries about flooding due to heavy rain, and the risk of minor coasting flooding at the times of high tide. Just more nastiness being thrown at New Jersey from this potent winter storm.
Here's the latest advisories map. Be safe this evening!
ORIGINAL POST from 8:47 a.m. Saturday...
I've been stressing for a day or two now that, for most of New Jersey, our impending weekend winter storm is NOT going to be a snow bomb. (I've been regularly calling it a snow-ice-rain storm.) The latest forecast models continue to bear out that idea — we find ourselves even more on the "warm" side of the side. Less snow, more rain. But still plenty of nastiness to be found:
--Heavy snow in North Jersey, especially right at the storm's onset
--Heavy rain throughout most of the state, with rumbles of thunder possible
--Significant icing threat due to freezing rain, especially along the I-78 and I-80 corridors
--Wind gusts to 50 mph
--Another icing threat from a flash freeze, as crashing temperatures cause puddles and wet surfaces to freeze
--Bitter cold, with potentially dangerous wind chills well below zero
Freezing rain is one of the most challenging weather phenomena to predict. It takes a very specific set of circumstances — an intrusion of warm air about a half-mile to a mile above the surface (called a "warm nose"), and a shallow pool of subfreezing air near the ground.
Worst-case scenario? Several hours of freezing rain. A layer of ice would be very slippery and very heavy, potentially causing impassible roads and widespread power outages.
Best-case scenario? A quick hit of snow for central and northern NJ, followed by a rapid transition to all rain. Snow totals would be no more than an inch or two for the vast majority of New Jersey. Still very cold, and pretty icy too. I would take massive heat for hyping "doom and gloom" of a potential ice storm. That's OK — the potential danger here is worth that headache.
For my latest snow map, I made a few changes, mainly to the numbers rather than the contours:
--Orange contour stays exactly the same, but I tweaked snow numbers down (6-12" becomes 4-8+"). All models now show the true "thumping" of snow staying north of Sussex County. I'm still leaning toward a slightly colder forecast than others have suggested, so I included the "plus" to account for over performance in this area.
--Blue contour also covers the same area, but I also pushed snow totals down (3-6" becomes 2-4"). I think this better communicates the snow potential being limited to far northern New Jersey, and will much more closely match the reality of this storm.
--Dark green contour, the "mostly rain zone," nudges farther north, removing most of the I-295 corridor in SW NJ.
--Light green contour, the "rain zone," now firmly encompasses approximately the southern half of the state. This area may see rain, rain, rain throughout the entire storm. But my gut tells me a quick coating of snow is possible right at onset. I've never included a half-inch in a snow forecast before, but it just feels right to include the possibility here.
The storm's timeline generally remains the same:
--Saturday afternoon-evening: A quick burst of snow arrives from the west. (Probably just rain, south and coast.) Exact arrival time will depend on the location and orientation of the storm's outer edge. If anything, models have been trending toward a later "evening" start time.
--Saturday night: As warmer air invades the atmosphere and temperatures rise, a transition from snow to wintry mix to rain will take place. Again, North Jersey will stay snowy for a little while longer, while the southern half of the state (at least) will probably see rain for almost the entire storm.
--Early Sunday morning: The "wintry mix" transition phase of the storm could bring an extended period of sleet and freezing rain to north-central NJ.
--Late Sunday morning: Temperatures start to tumble, on a brisk wind. (Northwesterly, sustained 15 to 25 mph, gusts to 50 mph.)
--Sunday midday: A brief return to snow and/or wintry mix is possible as thermometers dip below the freezing mark.
--Early Sunday afternoon: Precipitation wraps up, but gusty cooldown continues. A flash freeze is possible, as puddles and wet surfaces ice over.
--Monday morning: Temperatures in the single-digits. With the wind, it'll feel like -5 to -15.
And there are some minor updates to our advisories picture:
--Winter Storm Warning from Noon Saturday to 6 p.m. Sunday... western Bergen, western Essex, and Passaic.
--Winter Storm Warning from 1 p.m. Saturday to 4 p.m. Sunday... Morris, Sussex, and Warren.
--Winter Weather Advisory from 1 p.m. Saturday to 1 p.m. Sunday... Hunterdon, Middlesex, and Somerset.
--Winter Weather Advisory from 4 p.m. Saturday to 10 a.m. Sunday... eastern Bergen, eastern Essex, Hudson, and Union.
--Coastal Flood Advisory from 5 a.m. to 9 a.m. Sunday... eastern Essex, Hudson, and eastern Union.
As conditions are prone to go downhill rapidly Saturday evening, I offer my traditional reminder to be smart and stay safe! Our news, traffic, and weather teams are all on-duty this weekend to pass along the latest information.
I'll probably bang out another weather blog update as the storm is ramping up Saturday afternoon.