By John Cifelli
NJTV News Meteorologist
A warm-up is on the way, but not before a round of accumulating snow Monday evening.
The cold air for this weekend has been every bit as advertised, with windchill values at or below zero for the northern half of the state, even after six hours of sunlight and daytime heating today. If you’re headed outdoors with your sweetheart this Valentine’s Day, make sure you bundle up and snuggle tight. Exposure to this kind of cold can result in frostbite or hypothermia. Temperatures will stick in the single digits and teens statewide today.
The strong area of high pressure centered over New Jersey, responsible for this incredible cold, will slide east off the coast, and the clockwise air flow around the high will circulate southerly winds over the mid-Atlantic tonight and tomorrow. Warmer air surges northward as a result, allowing the state to thaw throughout the day Monday. Warm air advection aloft is a mechanism for causing precipitation, and with the surge of warmer air will come a round of snowfall during the day. Beginning shortly after the morning commute, light snow will begin across southwest New Jersey, and spread north throughout the day. By the evening commute, snow will be changing to rain in the south, and the changeover line will press northward later in the evening for the rest of the state. Low level cold can be difficult to scour out of the elevated portions of northern and in some cases central New Jersey in these kinds of events, and I think there will be a period of sleet and freezing rain north of the 202 corridor Monday night.
By daybreak Tuesday, we are above freezing statewide, but the roads could still be in poor shape in far northern New Jersey. The antecedent air mass is so cold that it will take a while for surface temperatures to rise above freezing, even if the surface air temperature creeps beyond 32 degrees Fahrenheit.
The heaviest snow and most likely time for accumulations comes with the evening rush. Most of the state, except south of the Expressway, will have not yet changed over to rain, and precipitation should be pretty steady along the warm front as it lifts north. One to two inches will fall for the southern half of the state, while two to four inches look likely north of 195, before the changeover to a wintry mix and then rain arrives after dark.
We continue to see the mercury rise on Tuesday as a surface low passes through Pennsylvania, increasing the southerly flow across the state and spreading steady rainfall across the state throughout the day. An inch or so of rainfall is possible Tuesday. I’ll raise caution for the possibility of some road flooding, as the ground will still be frozen and unable to absorb Tuesday’s rains. Monday’s snow and ice will be melting off as well. By Tuesday evening the surface low will have lifted north and we will return to a northwest wind, ushering in another round of seasonal cold for the rest of the work week. Besides a few stray snow showers Wednesday, things look dry for the extended period as well.