BETHLEHEM, Pa. — The first true widespread snow of the season is on the doorstep.
The Lehigh Valley is under a winter weather advisory in effect from 7 p.m. Saturday to 7 a.m. Sunday for total snow accumulations of 2 to 4 inches.
The advisory covers Berks, Lehigh and Northampton counties, but the snow is expected to blanket much of the greater mid-Atlantic for the first time, including the Philadelphia metro area and the Interstate 95 corridor.
By Sunday, snow will stretch all the way to the nation’s capital, forecasters say.
EPAWA Weather Consulting graded its “winter storm impact level” at 3 out 5 — or “significant” — for a swath of the region that stretched from the Lehigh Valley to southeastern Pennsylvania.
Timing
Saturday morning, forecasts indicated a few light showers expected to move into the region later today, followed by a more organized round of precipitation this evening that will last into early Sunday morning.
The National Weather Service said temperatures will warm up today, especially south and east of I-95, so the precipitation in those areas may start as rain and change over to snow later tonight and into the overnight.
The heaviest snow is likely to fall after midnight, the latest forecast discussion said, which is a less disruptive time for most people.
Snow should taper off fairly quickly early Sunday morning, ending from northwest to southeast.
After an arctic cold front passes, strong northwest winds will move in, which could cause some blowing and drifting snow and make it feel much colder.
The worst of those conditions is expected Sunday night.
Totals tick up
The main update to the forecast Saturday morning was a slight increase in expected snowfall, which led forecasters to expand the winter weather advisory both north and south.
Across a large central area, forecasters now expect widespread snowfall totals of 3 to 5 inches.
Some forecast models suggest a narrow area could see even higher amounts, possibly reaching warning-level snowfall, but that is still uncertain, especially since some precipitation may be lost during the change from rain to snow.
For now, forecasters are sticking with a winter weather advisory for this region, though snowfall totals could end up near the higher end of that range.
