The latest winter storm forecast now calls for 7 to 10 inches of snow across much of the Lehigh Valley Monday evening through Tuesday.
The National Weather Service has issued a winter weather advisory from midnight Monday to 3 p.m. Tuesday for Northampton and Lehigh counties in Pennsylvania and Warren County in New Jersey, as well as surrounding areas.
The weather service says heavy snow is expected, with larger amounts forming at higher elevations, especially in northern Warren County and neighboring Morris County areas.
The weather service said the timing of the storm, with 1 to 2 inches falling per hour after midnight, would likely make the morning commute difficult. This means some regional school districts could move to remote learning, postpone openings, or close all together.
“This is a very dynamic meteorological setting, and these dynamics will produce particularly heavy rain in the cold sector of this fast-moving storm, resulting in heavy snowfall,” the weather service said.
The amount of snowfall in the Lehigh Valley depends on how quickly a coastal low takes over and intensifies, and thus how quickly cold air is pulled south late Monday into Tuesday morning, turning to snow from the Poconos down to the I-95 corridor, the weather service says. .
At Lehigh Valley International Airport in Hanover Township, Lehigh County, the weather service expects it to be mostly cloudy Monday with a high near 50 degrees. The weather service says winds will be calm west at about 5 mph Monday afternoon.
Meteorologists at both the weather service and AccuWeather say Monday evening is when things are expected to change.
Forecasters say this is the time when warm air ahead of the system will bring an initial round of rain to much of the region, expected sometime between 9pm to 10pm on Monday. The rain is expected to continue until 3 a.m. on Tuesday.
Then, with temperatures dropping to around 32 degrees, snow is expected to fall early Tuesday. The weather service says the chance of rain is 90% with 1 to 2 inches of snow accumulation possible.
Tuesday's snow is expected to fall mainly before 2 p.m., and could be heavy at times with wind gusts up to 30 mph. The maximum temperature is expected to reach 36 degrees. The chance of rain is 100% with 5 to 9 inches of snow accumulation possible.
Everything is then expected to clear up by Wednesday, but there is still a bit of wind.
The Meteorological Department expects the weather on Wednesday to be sunny, with temperatures rising to approximately 35 degrees. Winds are expected to be northwesterly at 10 to 15 mph, with gusts up to 25 mph. By Wednesday evening, the weather is expected to remain mostly clear, with a low around 22 degrees.
The next chance for more snow could come Thursday. The weather service expects rain and snow after 2 p.m., with a 30% chance of rain.
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Pamela Sroka Holzman can be reached pholzmann@lehighvalleylive.com.
