From LWX (4:33 AM)
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Low pressure will traverse the area Friday. It`s weak, but there`s
notable warm advection in the 850-700 hPa layer, tucked under a
modest coupled upper jet structure and mid-level PVA. Given the cold
temperatures, any precipitation that falls will be snow and have no
trouble sticking. East of the mountains, lift is focused in the
dendritic snow growth zone, so despite low-level dry air believe
there should be at least some steady light snow in the I-81 corridor
and near/north of US-50. Along and north of I-70, moisture and lift
are a bit better and this is where the best chance for plowable snow
exists east of the mountains.
As far as the ridges of the Allegheny Highlands go, lift here is
actually a bit below the dendritic snow growth zone. Cold
temperatures should yield ratios close to 18:1, but with low
inversion heights and less than ideal wind trajectories, current
most likely forecast is for sub-warning level snow (solid advisory,
3-6"). Therefore, have opted not to go with a watch at this time.
Advisories will likely be needed over the mountains and in northern
Maryland (especially given the cold ground and potential impact) for
Friday, if current forecast projections remain on course.