WEATHER

Severe Winter Storm Arrives Tonight

20170313_snowmap_squareBy John Cifelli
NJTV News Meteorologist

– Over a foot of snow likely for much of the state, isolated areas nearing two feet
– Sleet and rain cuts down on snow totals south and east of the Turnpike
– Blizzard conditions possible along the coast from Monmouth north
– Precipitation begins Monday night before midnight

An intense, potentially historic snowstorm will bear down on the Mid-Atlantic Monday, spreading snow north and a wintry mix south across New Jersey. Coupled with strong winds and the potential for beach erosion and coastal flooding, this is a multi-faceted, powerful and dangerous storm slated to impact New Jersey beginning tonight.

We find ourselves today still in the cold grip of an Arctic air mass. Twin high pressure centers, 1040 mb on the border of North Dakota and Canada, as well as 1032 mb in southeast Ontario, continue to reinforce the cold air across the state. That will continue as the upper level pattern pins them in place for the duration of our winter storm. In fact, the track of tomorrow’s storm is very close to the coast, and if it were not for the anomalous fresh cold air source, most of the state would be looking at plain rain. As of 10 a.m. this morning, nowhere in New Jersey was above freezing, and we will remain 15 to 20 degrees below normal all day.

That sets the stage for this evening. A hybrid system, energized by upper level energy in three different branches of the jet stream, will coalesce and deepen off the Virginia cape. As it slides north and then gradually northeast, precipitation will break out across southern New Jersey as early as 9 p.m. tonight. I think everyone sees some snow to start, but it will be short lived for Cape May, Cumberland and Atlantic counties. With the wind blowing off the Delaware Bay and Atlantic Ocean, no high pressure in Canada is going to stop the marine influence from changing things over to rain here. As the night progresses, the progression of precipitation and the rain/snow line spreads north. By daybreak most of the state is seeing snow, with several inches on the ground already in interior southern and central New Jersey, as well as the Philadelphia metro.

This is where things get interesting and tricky. The surface low will shift east-northeast after passing east of Atlantic City mid-morning, turning the winds back to the north across southern and central New Jersey. Cold air at the surface will flood back to bring temperatures below freezing, but low pressure aloft most likely will have ended precipitation by the time that happens. With these types of powerful storms, we look for “dryslots” based on the track of low pressure centers aloft, and I think the low at 700 mb will punch a hole in the chances for a return to precipitation for everyone along the Atlantic City Expressway and points south. As a result, the snowfall painted on the forecast map represents what falls at the beginning, but much of this may be washed away during the change to rain. For southern and coastal New Jersey south of Long Beach Island, the bigger issue will be wind and flooding concerns. Expect wind gusts of 50 to 60 mph along the shore. The full moon, persistent east-northeast winds and close proximity of the intense low pressure center will swell east-facing bays and inlets, bringing flooding to moderate stages with the high tide.

Elsewhere, mid-morning will be an incredible scene, with perhaps some of the most intense snowfall rates recently observed. There may be a banded structure to the snowfall from early to late morning, which could lead to ebbs and flows in intensity, but for Mercer and Middlesex on north, including the New York City metro, snow will fall up to four inches per hour at times. That threatens the area with whiteout conditions, especially with any gusty winds.

Speaking of winds, the National Weather Service has upgraded eastern Passaic south to the southern end of Ocean County to a Blizzard Warning. For this to verify, this part of the state would experience sustained winds of 35 mph and visibility below one-quarter mile for three straight hours. Elsewhere in northern and central New Jersey, winds will gust that strong, but they will not be sustained at 35 mph. Although the Blizzard Warning does not extend into interior New Jersey, blizzard conditions will be realized from time to time as the winds gust to meet the threshold. Don’t plan on moving much tomorrow morning. It will be dangerous.

The saving grace for this storm is that this is not a long duration event; it is more average in that respect — about 15 hours or so. By early afternoon, accumulating precipitation is ending statewide, although snow showers could linger as the upper level low at 500 mb swings through Tuesday evening, possibly even into Wednesday morning. Northwest winds on the back side of the departing low will also reinforce the cold temperatures. We will not see temperatures creep above the freezing mark anywhere in New Jersey until Thursday.

I’ll have another update this afternoon, and will be on air tonight at 6 p.m. Stay tuned.