Frigid air is moving out, but stormy weather is moving in on Monday and Tuesday. Watch video
The bone-chilling Arctic air that turned New Jersey into a giant ice box for the past few days is finally drifting out of our area Monday morning, only to be replaced by a storm system packed with a potentially dangerous mix of snow, sleet and freezing rain.
Here's what to expect in terms of the storm's timing and impact:
Timing of the storm
The Presidents Day storm system, which is moving in from the Ohio and Tennessee Valley regions, will start dropping light snow over Philadelphia and the Interstate 95 corridor in southern New Jersey by mid-morning Monday, the National Weather Service said. The snow should start moving into central New Jersey by the mid- to late morning, then northern New Jersey by the afternoon.
As warmer air flows in from the south and east, the snow will eventually mix with sleet and change to rain.
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"The big question is how slowly or how quickly the temperatures are going to rise," because that will determine how much snow falls and how much ice accumulates before the snow changes to rain, said Larry Nierenberg, a meteorologist with the weather service's regional office in Mount Holly.
Even when plain rain starts falling as the atmosphere warms up, if temperatures on the ground are stuck at 32 degrees or colder, the rain will turn to freezing rain on impact. That could make for slick roads, the weather service warned.
"The further south you are, the sooner the changeover is going to occur," Nierenberg said.
This is the projected timing of the switch from frozen precipitation to rain, based on geographical region:
- Across southeastern New Jersey, the changeover is expected Monday afternoon.
- Across eastern New Jersey, the changeover is expected by Monday evening.
- Across the I-95 corridor, there may be a brief mixing of snow and sleet during the late afternoon and early evening before a conversion to all rain, the weather service said.
- In most of northern New Jersey, as well as the Lehigh Valley and Berks County, there will likely be a prolonged period of freezing rain, with the changeover to all rain not happening until daybreak Tuesday.
- For extreme northern New Jersey and the Poconos in northern Pennsylvania, the switch to all rain may not occur until late morning or early afternoon Tuesday, so that region could be hit with an extended period of icing.
"The most significant icing threat is in North Jersey and in northeastern Pennsylvania," Nierenberg said. "The good news for (Monday) is a lot of the schools are closed and there's going to be a lighter commute. If there's any silver lining, that is it."
Storm advisories
Winter weather advisories that were issued Sunday for most of central and northern New Jersey have been expanded to include the entire Garden State. The advisories start and end at various times for different regions.
* One advisory is in effect from early Monday morning through 4 p.m. in Atlantic, Cape May, Cumberland and southeastern Burlington.
* Another advisory is in effect from early Monday morning through 10 p.m. in Camden, Gloucester, Ocean, Salem, northern Burlington and western Monmouth.
* An advisory is in effect from early Monday morning through 10 p.m. for Mercer and Middlesex counties in New Jersey, as well as Chester, Montgomery and Philadelphia counties, plus lower Bucks County in Pennsylvania.
* An advisory is in effect from 10 a.m. Monday to 1 a.m. Tuesday for Hunterdon, Morris, Sussex and Warren counties in New Jersey. The same advisory is also active for Berks, Lehigh, Northampton, upper Bucks, western Chester and western Montgomery counties in Pennsylvania.
* Another advisory is in effect from 1 p.m. Monday through midnight Tuesday for Bergen, Essex, Hudson, Passaic and Union counties, as well as New York City and Long Island.
* A separate advisory is in effect from 1 p.m. Monday to 7 a.m. Tuesday for western Passaic and western Bergen counties, as well as southern Connecticut and the lower Hudson Valley in New York.
Here are the snowfall projections from the Presidents Day storm for eastern Pennsylvania and most of New Jersey, left, and northeastern New Jersey, New York City and parts of Connecticut, right. (National Weather Service) Snow and ice projections
The far northern and northwestern sections of New Jersey could get 3 to 4 inches of snow and a coating of ice before the precipitation all changes to rain. Some spots in northern Sussex County could get hit with 4 to 6 inches of snow.
Areas to the east and south of I-95 could see 1 to 2 inches of snow and some sleet and freezing rain, but likely not as much as that in northern New Jersey.
On Tuesday, rain could be heavy at times across the entire state, posing a risk of flooding, the weather service said.
Temperatures rising
After another frigid night, temperatures will be hovering in the single digits and teens early Monday morning, then slowly rising as the day progresses, forecasters said. The mercury is expected to rise into the low 30s in northern and western areas during the afternoon and into the upper 30s to low 40s in southern and eastern counties.
On Monday night, temperatures will remain in the 30s in most areas, before rising into the 50s on Tuesday, setting the stage for the rain.
Len Melisurgo may be reached at LMelisurgo@njadvancemedia.com. Follow him on Twitter @LensReality. Find NJ.com on Facebook.