SPC discussion
Areas affected...Portions of northeast OH...northwest PA...and
western NY
Concerning...Heavy snow
Valid 020143Z - 020745Z
SUMMARY...Moderate/heavy is expected overnight. Snowfall rates of 1+
inch per hour are expected, with localized rates in excess of 2
inches in the most intense snow bands.
DISCUSSION...Latest surface analysis shows a surface low progressing
eastward/northeastward near Pittsburgh, PA. Meanwhile, satellite
imagery indicates northern/southern stream phasing currently
underway over Ohio, with mid-level trough becoming negatively tilted
over the area. As this occurs, strong deep layer ascent associated
with intense frontogenetical forcing and a coupled upper-level jet
structure is expected to promote strong lift through a saturated
dendritic growth layer. Snowfall rates of 1+ inch per hour will be
common across the MCD area, with localized rates in excess of 2
inches per hour in the strongest bands. Snowfall rates are expected
to decrease in intensity late tonight as the surface low progresses
east of the area and deep layer ascent diminishes.
While rain is currently being observed across southern portions of
the MCD area, strong low-level cold air advection and dynamic
cooling is expected to increase tonight as the center of the surface
low progresses just south of the area. This will lead to a rapid
transition from rain to moderate/heavy snowfall near 0600Z.