Prepare for 'significant weather' later this week, forecasters say. But snow is not the biggest concern

BETHLEHEM, Pa. — While Santa is making his list and checking it twice this week, forecasters at the National Weather Service will be scrutinizing any snow that may fall on Christmas Eve.

That’s because just as Jolly Old St. Nicholas is meticulous in his work, so are the folks who hold fast to the specific definition of what constitutes a “white Christmas.”

• A "white Christmas" is defined by the National Weather Service as having at least one inch of snow on the ground on Christmas morning
• The Lehigh Valley has a shot at it this year because of a complex storm system taking aim at the region
• The storm should arrive Thursday into Friday

According to the weather service, it occurs when there is at least an inch of snow on the ground on Christmas morning.

But will it happen this year?

Meteorologists have been fielding more questions about it the last few days, with weather models circulating on social media (some as early as a week ago) showing a massive Christmas Eve snowfall.

They’re attention-grabbing, but are they correct?

Rain and gusty winds ahead. And then?

The storm expected to arrive in the area Thursday will bring heavy rain and gusty winds for much of the area, forecasters say.

It will be followed by a very cold holiday weekend.

How cold?

“Intense” is the word used by the weather service in its latest forecast discussion to describe the temperatures, which are expected to top out in the teens to our north and 20s elsewhere on both Saturday and Sunday.

“Wind chill readings will be in the single digits and teens. Overnight lows will range from the single digits north/west to the teens elsewhere. Wind chills overnight will be sub-zero north/west and single digits for other areas,” the discussion said.

And the cold will create problems on its own. That’s because the storm system targeting the area will bring several rounds of precipitation – including the potential for freezing rain, sleet and snow – as cold air rushes into the region just as the storm is pulling away.

It could create a flash freeze scenario, EPAWA meteorologist Bobby Martrich said in his latest video update.

“This is not your typical back-end snow situation,” Martrich said. “This is an arctic front.”

How much snow?

Martrich went on to describe the potential snowfall anticipated late Friday as “an inch or two, maybe three in some places.”

But the transition from rain to wintry precipitation and the rapid plummet in temperatures is most concerning. That’s because a flash freeze means there is a good chance for any liquid to quickly become ice, which can cause havoc on roads in an instant.

In this case, temperatures are expected to fall from the 50s, through the 40s and 30s and down into the 20s rather quickly.

“It’s going to create a flash freeze concern because you have all this rain that’s out ahead of it,” Martrich said.

The good news is that Saturday will bring strong winds, which should help to dry roads for Christmas Eve celebrations.

More details on this storm system are expected over the next few days, and the weather service offered this tip: “It’s a good time to prepare for some significant weather this week, especially for the colder northwest counties.”