NJTV News Weather: Snow Expected for First Day of Spring

20150318_SnowMapBy Meteorologist John Cifelli

On Friday we will boldly step forward into Astronomical Spring, with crocus and robin ready to soar with us toward the warm spring sun, right? Wrong! The weather doesn’t pay much mind to calendar dates, and as you surely noticed when you stepped outside today, we have slipped back into a wintry pattern. It seems likely that this pattern will manifest a snow event for most of New Jersey on Friday.

Relatively strong high pressure is in control today and tomorrow. Temperatures will be 10 to 15 degrees below average for this time of the year, which translates to highs in the 40s and lows in the upper teens/low 20s across the state. Thursday night, a weak area of low pressure across the Deep South will spread moisture across the mid-Atlantic and work in tandem with potent upper level features to bring light snow to New Jersey around daybreak. Temperatures will creep above freezing at the surface and aloft in southern New Jersey, but central and northern areas will see an all snow event lasting about 12 hours.

There are challenges to accumulating snowfall in late March that need to be considered with this event. Every day the sun angle climbs higher, which allows surface temperatures to respond in kind. We receive just as much solar radiation on Friday as we will in late September, so while the average temperatures then and now are different because of the way the earth is heated, the blacktop of a roadway has the same capacity for absorption of that sunlight, and the same ability to turn that light into heat. So besides the usual difficulties in snowfall forecasting, the thickness of the cloud deck and the time of day that snow falls have significant implications for accumulations too this time of year.

Given the marginal temperatures and daytime snowfall, I am hedging low for this event. I could see this being the type of snowfall where the roads whiten when it falls moderately, but then melt off when the intensity wanes. I think the bulk of the accumulations are realized on car tops and grassy surface, much less so on blacktop. This also will be a storm that favors elevation, so those at the top of the hill in their town will see a little bit more than those down in the valley. The best bet for travel concerns would be the afternoon/evening drive home in northern New Jersey and New York City metro where steady snow may linger as the sun starts to fall. If you still have steady snow outside your window by 4 p.m. Friday, roads will deteriorate quickly.

Accumulation expectations at this point are as follows:
Snow to rain, no accumulation for Cape May, Cumberland and Atlantic counties.
North of here, to the Route 1 corridor including all of Philadelphia, and Staten Island — a coating to an inch, with rain mixing, particularly south
From Route 1 to Route 80 including New York City — one to three inches, mostly on grassy surfaces until the evening
North of Route 80 — two to four inches

By late evening, it’s over statewide.

Saturday will be a decent day in the low 40s with sun and clouds with perhaps a sprinkle in the late afternoon.