BETHLEHEM, Pa. — As temperatures continue to fall, the Lehigh Valley’s December snow totals continue to climb.
After a wintry blast Wednesday that dropped as much as 3.1 inches of snow in parts of the area, forecasters say more could be coming this weekend.
The National Weather Service said another fast-moving system will sweep into the Great Lakes on Saturday. As it does, much colder Arctic air will push in behind it, spreading across the northern and central Plains.
The system will help create a new upper-level disturbance that will move through the Ohio Valley and into the Mid-Atlantic. At the surface, an area of low pressure is expected to develop near the base of the disturbance and track through our region Saturday night.
Forecast details still are coming together, but several models currently show the low forming near the Tennessee Valley and heading toward the mid-Atlantic, with snow expected to become the main type of precipitation as the system moves over the region.
Timing, accumulation
The latest guidance shows a moderate chance of accumulating snow late Saturday night.
“I do think Saturday is going to be a dry day,” EPAWA meteorologist Bobby Martrich said in his latest video update. “Then snow is going to come in overnight.”
Martrich said there’s still some question about the exact axis of the system, and emphasized it’s “fast-moving and not going to turn into this big, gigantic storm.”
“It has limited upside because it’s moving so fast,” he said.
A jet streak will determine who gets the heaviest snowfall rates, he said, with an “upside of maybe 2 to 4 inches. That’s kind of what we’re looking at.”
A jet streak in winter is a powerful, fast-moving core within the main jet stream, driven by bigger north-south temperature contrasts, according to the weather service.
Jet streaks lead to intensified weather patterns such as stronger storms and significant cold air outbreaks, affecting precipitation and temperature across the United States and beyond.
Martrich said the system might even be targeting areas that haven’t seen snow yet, including southeastern Pennsylvania and the Philadelphia metro area.
“I think you’re in line for what should be a couple inches of snow,” he said.
Deterministic models early Thursday put the Lehigh Valley area at 3 to 4 inches, with snow beginning after midnight and tapering off Sunday morning. But outlooks could change, with lower totals possible.
I’m dreaming of a … warm Christmas?
After the snow, a strong cold front will sweep through, bringing in much colder air, the weather service said.
High temperatures will only reach the mid- to upper 20s Sunday, with northwest winds increasing to 15–20 mph with gusts up to 30 to 35 mph, creating wind chills in the teens to low 20s through the day.
As of Thursday morning, Allentown’s monthly average temperature was 28.3 degrees — a 9.1-degree departure from average.
It’s the eighth-coldest start to December ever for the Lehigh Valley, but there are signs of moderating temperatures ahead, perhaps even warming into the upper 40s by late next week.
The Climate Prediction Center’s 8-to-14 day outlook (valid Dec. 18-24) shows a 40-50% probability of above-average temperatures.
How much snow fell Wednesday? These were some of the totals reported by the National Weather Service?
Northampton County
Nazareth 3.1 inches
Moore Twp. 2.6 inches
Danielsville 2.5 inches
Bushkill Twp 2.3 inches
Bath 2.3 inches
Lehigh County
Neffs 2.0 inches
Germansville 1.4 inches
North Whitehall Twp. 1.4 inches
