A winter storm watch has been issued for the Lehigh Valley and surrounding region as the potential for a coastal storm to deliver a significant snowfall increases.
The watch, issued for Sunday morning through Monday afternoon, warns of heavy snow, with total accumulations potentially exceeding six inches, according to the National Weather Service.
In its Friday afternoon forecast discussion, the weather service said the possibility of “widespread accumulating snowfall” continues to increase; however, confidence in the forecast remains low. The weather service said more detailed snowfall estimates would begin to come into focus later Friday night.
While the forecast models are moving into alignment that low pressure moving off the Southeast or Mid-Atlantic coasts Saturday night into Sunday will strengthen as it moves out to sea, that’s where the agreement ends.
As has been the case for several days, the models are showing two vastly different scenarios for how the storm could play out, which will determine whether we end up with a run-of-the-mill snow event or a blockbuster.
If the system tracks closer to the coast and strengthens, more intense impacts will be felt, including heavy, rapidly falling snow and high winds. If the system stays weaker and moves further out to sea, then much lower snowfall amounts would be expected, and the precipitation could even start as rain in some areas, according to the weather service.
The eventual outcome could fall somewhere in between those scenarios, the weather service noted in its forecast discussion Friday afternoon.
“While the uncertainty remains high, the outcome may become more in the middle with a deepening storm offshore but not as quick as the more robust guidance.”
In addition to heavy snow, the storm has the potential to bring wind gusts of up to 35 mph, according to the weather service. Travel could become very difficult, if not downright hazardous, all the way through Monday evening.
After the storm, colder air will settle in over the region through Tuesday. High temperatures in the 30s are expected, a noticeable change from the milder weather this week. Warmer air will return by later next week, according to the weather service.
Here is the extended weather service forecast:
Saturday: Partly sunny, with a high near 46. West wind 5 to 10 mph.
Saturday night: A slight chance of rain and snow between 1 and 4 a.m., then a slight chance of snow after 4 a.m. Mostly cloudy, with a low around 30. West wind around 5 mph becoming calm. Chance of precipitation is 20%.
Sunday: Snow likely before 7 a.m., then snow, possibly mixed with rain between 7 a.m. and 4 p.m., then snow after 4 p.m. High near 39. East wind 5 to 10 mph, with gusts as high as 20 mph. Chance of precipitation is 90%. New snow accumulation of less than a half inch possible.
Sunday night: Snow, heavy at times. Low around 30. Chance of precipitation is 90%.
Monday: A chance of snow before 1 p.m. Cloudy, with a high near 38. Chance of precipitation is 50%.
Monday night: Mostly cloudy, with a low around 23.
Tuesday: Partly sunny, with a high near 33.
Tuesday night: Mostly cloudy, with a low around 20.
Wednesday: A chance of rain and snow. Mostly cloudy, with a high near 41. Chance of precipitation is 30%.
Wednesday night: A chance of rain. Mostly cloudy, with a low around 33. Chance of precipitation is 50%.
Thursday: A chance of rain. Mostly cloudy, with a high near 45. Chance of precipitation is 50%.
This is a developing story. Check back for updates.