By Meteorologist John Cifelli
At 8 p.m., temperatures were settling into the low 30s from Mercer-Monmouth north, with upper 30s and a few readings in the 40s south of 195. The surface high pressure center is flexing in eastern Canada. At 1036mb, it is driving cold southward through New England and into northern New Jersey. Despite an advancing low pressure center from the west, temperatures will gradually drop below freezing for everyone north of 195. It’s foggy out too, there’s plenty of moisture around and freezing fog will occur with sub-32 temperatures tonight. Temperatures will continue to fall over the next 24 hours. I don’t think there is any diurnal heating with daylight tomorrow if you are north of the cold front that the area of high pressure is shoving southward over New Jersey. The cloud cover is thick, the air mass is moist and as a result, whatever falls tonight and tomorrow will be frozen.
Aloft, temperatures are another story. It’s above freezing for most of New Jersey at 925mb (a few thousand feet up in the air) and all of New Jersey at 850mb (higher yet, vertically). This spells a lot more sleet and freezing rain, and a lot less snow. When I last posted about this storm, I was pretty gung ho about significant snowfall for those north of route 80, but even here I think warming aloft will spoil snowfall totals in favor of sleet and freezing rain.
Precipitation has been scant thus far. Moisture is ample, but the best lifting mechanisms to squeeze the moisture out of the atmosphere, have thus far skipped just north into New York and Connecticut. I still expect these features to shift southward overnight and by morning, light sleet or freezing rain will be falling in the northern half of New Jersey. For the 195 corridor and the northern suburbs of Philadelphia, although surface temperatures will be at or below freezing, it may not be precipitating at 6 a.m. So for the morning commute tomorrow, a glaze on untreated roads and sidewalks looks likely for Route 1 and points north, causing a potentially dangerous drive.
As the day progresses and low pressure gradually passes to the southeast of our state, temperatures at the surface and aloft will continue to cool. Sleet and freezing rain in far northern New Jersey will transition to light snow and freezing rain for the 78/202/1 corridors will eventually yield to sleet, possibly ending as a few flakes. Further south, cold air never works in aloft in time for snow to fall.
This will be a long duration light intensity event. Salt works with temperatures at 31 or 32, so even if you wake up to a temperature near freezing in the borderline area around 195, you might be able to scoot into work without issue. However, temperatures will continue to fall, and if it starts to drizzle during the rest of the morning, roads could ice up here too. Statewide, we should be drying out by the evening, although some models suggest light precipitation lingers past dark.
North of Route 80 — a light glaze of ice, then 2-5″ of sleet and snow
202 and 78 corridors, including Manhattan and the Bronx — 0.2″ ice accrual, then 1-2″ sleet and snow
195 and Route 1 corridors, including northern Philadelphia, Queens, Staten Island and Brooklyn — up to 0.2″ ice accrual, followed by a coating of sleet and snow
South of 195, southern Philadelphia — potential for a light glazing of ice, probably after the morning commute.
Listen to a traffic report tomorrow before you head out, check your surface temperature, know what to expect. Go slow and be safe!