... Snow, mainly south and east of Pittsburgh, will taper off tonight behind an exiting cold front. Dry and colder conditions are expected through Thursday before a warm-up this weekend.
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Quick update to increase POPs and snow accumulations across Nrn WV and Wrn MD, where a band of snow developed in divergence and shortwave support aloft behind an exiting cold front. Near term model and radar trends indicate this band should weaken over the next hour or two as it moves east, though accumulation of an inch or two is possible this evening.
Deep layer moisture and upper support/lift should gradually shift east of the area later tonight, with snow ending. A few lake/terrain enhanced snow showers are possible N of I 80 tonight as the flow becomes wrly, though building high pressure should end this potential by morning.
As cold advection continues, temperature will maintain its fall through tonight, with minima reaching the low-mid 20s late tonight despite sustained cloud cover.
SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... Colder and drier air will arrive on Wed as high pressure begins to build across the region in the wake of the exiting upper trough and downstream of a wrn-CONUS ridge. Amid clearing sky, light wind and building sfc high pressure, temperature seems likely to fall considerably more on Wed night, potentially into the mid-teens in many areas.
Flow aloft will flatten on Thu, aiding in the progressive exit of sfc high pressure and an eventual development of sly return flow. Although Wed will be cold and potentially peaking in the upper 20s, Thu will see a steady warm-up into the 30s (albeit still below seasonal average) amid increasing sunshine.
LONG TERM /FRIDAY THROUGH TUESDAY/... There remains higher confidence in the evolution of the upper-air pattern late in the week, as an upper trough amplifies in the central CONUS. This pattern will support increasing swly flow and strong warm advection for the Ohio Valley, leading to seasonably warm days and increasing chances for rain, particularly over the weekend.
However, by Monday, there is increasing confidence in a potential setup that might favor wintry precipitation in the ridges. In particular, the pattern appears somewhat favorable for freezing rain in Garrett County, with high pressure northeast of the region and strong warm advection on swly flow. Given the pattern and a 30-50% probability of 0.25" rainfall this far out in time, the concern will be mentioned in the extended portion of the HWO.