The National Weather Service sees three possible snowy scenarios for Western Pennsylvania this weekend.
In a Facebook post Tuesday, the weather service broke down the forecast and outlined some potential outcomes. Meteorologist Colton Milcarek said it will be a few days before a single clear prediction emerges.
“It’s really up to Mother Nature,” Milcarek said.
On Tuesday, the Pittsburgh office issued a cold weather advisory for the region, warning wind chills as low as 15 degrees below zero could cause hypothermia or frostbite.
Temperatures are expected to ease a little Wednesday and Thursday before dropping again significantly.
How much snow should be expected headed into the weekend remains up in the air.
What are the possibilities?
A first scenario for weather this weekend shows a storm track staying south and leaving the region with very little snow, the post said.
“This scenario is around 20% likely at this point given current weather prediction guidance,” the post said.
The second scenario shows a storm track forming to the south and curving north as it heads toward the mid-Atlantic region.
“In this scenario, the region would see snow, but not the worst of the storm,” the post said.
If this storm track were to hold, the National Weather Service said snow accumulations would likely be between 1 and 6 inches.
“This scenario is around 50% likely at this point, given current weather prediction guidance,” the post said.
The third scenario shows a storm track forming to the south before curving up the spine of the Appalachians and reforming off the coast. This scenario would create the heaviest chance of snow, with the possibility of snowfall between 6 and 12 inches, the post said.
“But this scenario is 30% at this time, given current weather prediction guidance,” the post said.
How does weather forecasting work?
Meteorologists begin by looking at the weather about seven to 10 days ahead of time and begin to dwindle that information down to possible weather scenarios around five days out, Milcarek said.
The possible weather scenarios are derived from a culmination of more than 100 weather-predicting models. As the day gets closer, Milcarek said, meteorologists are able to determine the worst, best and most likely scenarios.
In the social media post, the NWS compared forecast uncertainty to riding a train.
“We like to think about the forecast as a train heading into the rail yard. You start on one track. As you go through time, that one track turns into two, then perhaps four, and eventually, you could end up with tens of potential tracks the train could take as it arrives,” the post said.
As the weekend approaches, the weather models will begin to look the same, making it possible for meteorologists to provide a more concrete prediction.
To stay up-to-date on the NWS forecast, visit the website.