NJ weather: Timeline of rain/snow, flash freeze, dangerous cold
The Bottom Line
Friday is the big "holiday getaway" day, as the Christmas weekend inches closer. It is also going to be a tumultuous weather day, with rapidly changing conditions from morning through afternoon.
The big story is the arrival of an arctic cold front, sending temperatures plummeting, from the 50s into the 20s. That means a few things: 1.) rain may briefly flip to snow for an hour or two, 2.) puddles and wet surfaces could "flash freeze", and 3.) wind chills will end up in the danger zone.
This is going to be New Jersey's coldest Christmas in decades. Let's run through the specific timeline, so you know what to expect.
One Last Push of Rain/Snow
As of this writing (6 a.m.), overnight bands of heavy rain have exited New Jersey. Both rainfall totals and wind gusts ended up slightly lower than forecast estimates. Meanwhile, temperatures are in the 50s across almost the entire state. A Wind Advisory remains in effect until Friday evening, with gusts still popping over 40 mph at times.
We catch a break of dry weather for several hours Friday morning, coinciding with the AM rush hour. Then one more batch of rain will arrive in the late morning hours, starting around 9 or 10 a.m. That will exit early in the afternoon, by around 1 or 2 p.m.
There is a chance that "grand finale" rain briefly flips to snow, for an hour or two, as colder air arrives. A coating of accumulation is possible, especially in colder northwestern New Jersey.
Potential Flash Freeze
My biggest concern for this busy travel day continues to be the flash freeze potential.
Look outside this morning. See all those puddles and wet surfaces? As temperatures plunge below the freezing mark, they are apt to suddenly ice over. That would make for a very slippery scene Friday afternoon.
The critical point will be around midday. 11 a.m. along the western edge of the state. Closer to 1 p.m. near the Shore. That's when temperatures are forecast to dip below 32 degrees, the freezing mark.
By sunset, I expect to see widespread 20s across the state. So the afternoon hours are going to be the most precarious and most treacherous. The worst-case icing scenario is pretty scary, and could lead to major travel snarls. Remember, crews are unable to pre-treat the roads due to the precursor rain.
Dangerous Wind Chills
It's not just going to be cold Friday night, the combination of arctic wind and low temperatures will yield dangerously cold conditions. A Wind Chill Advisory has been issued for most of New Jersey.
Thermometers will bottom out around 10 degrees by Saturday morning. I expect to see lots of single digit temps — our coldest since late January.
Meanwhile, the wind will continue to blow, gusting to 30 mph overnight. That will push the wind chill to between zero and -10 degrees. Bitterly cold — make sure you bundle up warmly to mitigate the threat of frostbite and hypothermia.
The Rest of the Forecast
I really hope you have a warm place to spend this Christmas weekend, because temperatures are going to stay in the deep freezer for the duration.
High temperatures on Christmas Eve Saturday will only reach the teens across most of the state. It will still be windy, of course, keeping the wind chill in the single digits at best.
Christmas Day Sunday will only be slightly better, as temps push into the mid to upper 20s. Still below freezing. But at least sunshine and dry weather will make traveling easy.
Mostly sunny and freezing mark Monday. Warming into the mid 30s on Tuesday and near 40 on Wednesday — finally above freezing!
The final week of the year looks pretty quiet — long-range models don't plug in our next opportunity for a storm until New Year's.