Forecast Discussion
Summary
SYNOPSIS
... High pressure over southern Canada and northern New England will continue to wedge south along the eastern Appalachians through midweek. Onshore flow will continue as a result with cloudy, cool, and at times showery conditions. High pressure will breakdown Thursday into Friday as a weak wave of low pressure pushes through. Drier conditions and slightly warmer temperatures return with high pressure early next week.
NEAR TERM /THROUGH TONIGHT/... Canadian high pressure continues to linger further north, wedging an upper trough towards the Mid- Atlantic with a weak low pressure off the coast. Onshore to northeasterly flow will continue to bring more moisture and clouds across the area for the time-being today. Given the airmass, high temperatures today will struggle to reach the low 60s for most areas, with 50s across the higher elevations. Overall precipitation chances will decrease as the afternoon and evening progresses, with slight- chance to chance PoPs in place through tomorrow morning. Winds may be elevated for a few hours this afternoon with increasing pressure gradient but it should be brief in nature through early this evening.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... Wednesday will also continue northeasterly flow with on and off showers and periods of drizzle across much of the forecast area. The upper trough may begin to deepen as a result of the canadian high pressure and may result in slightly improved conditions by Wednesday afternoon. Some breaks in the clouds may be possible later in the day Wednesday with precipitation chances decreasing sharply into the afternoon and evening hours. A warming trend is expected to begin Wednesday, with highs increasing into the mid to upper 60s for most areas with upper 50s for the mountains expected. By Wednesday night, lows will drop down into the upper 40s to low 50s generally for the area.
By Thursday, the upper trough will move further east and bring a slight increase in moisture with it given the synoptic pattern and prevailing onshore flow. Some more instances of breaks in the clouds will be possible for the afternoon hours but rain chances will linger slightly throughout the day. Highs will increase further into the upper 60s to maybe some low 70s for the lower elevations and nearing 60 for the higher terrain. By Thursday night, lows will continue to be in the 50s to near 60 right along the waters.
LONG TERM /FRIDAY THROUGH TUESDAY/... The weather pattern begins to flip as we get toward the latter half of workweek. The wedge will begin to slowly erode as the remnants of Ophelia and the resultant upper level trough kick south/east of the region. This will allow for more dry air to filter into the region while tapering the persistent onshore flow.
Current 12z deterministic/ensemble guidance continues to show this process with the erosion of the wedge in areas west of the Blue Ridge Saturday and areawide Sunday. Most of the guidance still hints on a marine influence with a shallow layer of moisture lingering in the low levels east of the Blue Ridge through at least Saturday afternoon. Some uncertainty remains based upon the quickness of the upper level trough Friday into Saturday combined with the placement of the remnant low from what is left of Ophelia off the VA/NC coast. Either way look for decreasing shower chances and warming temperatures through the weekend. Highest rain potential will be on Friday areawide with a shift east of the Blue Ridge Saturday morning into Saturday afternoon.
A broad ridge of high pressure builds back into the region from the central Plains and Ohio River Valley Sunday into early next week. This will further erode the wedge pattern with flow turning toward more of the north and northwesterly direction. More sunshine will also be noted along with slightly warmer temperatures near 80 degrees. The warmer temperatures and drier conditions look to continue through much of next week.