Forecast Discussion
Summary
SYNOPSIS
... Scattered shower will increase in coverage today through early Friday as a large, slow moving upper level system drifts across the Upper Ohio Valley. Dry weather is then expected with high pressure this weekend into next week. Temperatures will gradually warm through next week.
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... A few light, isolated showers continue across eastern Ohio and northern West Virginia this afternoon as weak waves ripple through the mid-level flow. Meanwhile, persistent easterly flow continues to advect dry air across the region. This has cleared much of the cloud cover over western PA, and kept light showers from getting much farther north/east than Wheeling, WV.
Upper low pressure will slowly shift eastwards overnight, becoming centered over Michigan by Thursday morning. This crawl to the east will shift increasing shower chances across eastern Ohio through early Thursday morning. Showers will likely stop short of the northern WV panhandle.
Temperatures remain close to seasonal averages.
SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/... Better shortwave support and slow eastward movement of the upper low will increase shower chances across the area on Thursday. However, the shortwave will lift northwards during the afternoon, decreasing rain chances once again. While rain may briefly make it into the Pittsburgh metro region, areas farther east are much less likely to see rain during the day.
Better eastward progression of the upper low is expected Thursday night and Friday, keeping scattered showers in the forecast through the overnight into early Friday morning. However, models continue to indicate the associated rain shield will decay overnight with lack of deeper moisture.
Lingering showers should mostly clear the area Friday morning as the broadening low crosses the area and forcing diminishes. However, isolated light showers and/or drizzle may persist into the afternoon.
Weak warm advection ahead of the trough will warm temperatures several degrees on Friday versus Thursday.
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Upper ridging will begin Friday night into Saturday as the upper trough/wave exits east. Broad surface high pressure and a strengthening ridge will then dominate weather over the eastern CONUS this weekend and into the middle of next week. This pattern will foster dry weather and seasonably warm temperature through the period. The degree of warming will depend on ridge strength/positioning, but ensembles indicate only about a 3 degree change between the current forecasted values and the 90th percentile (high-end) possibilities.