... Moisture will continue atop another high pressure center ridging down from the north into Wednesday with cloudy, damp, and cool conditions lingering through Thursday. Expect a slow warm up and drier conditions beginning Friday which will continue into next week.
NEAR TERM /THROUGH WEDNESDAY/... As of 730 PM Tue: Forecast remains on track with surface high pressure in Quebec extending southward over much of the Eastern Seaboard. As a result a wedge-like pattern has developed over our CWA. We lack upper level confluence over the northeastern CONUS that would normally be seen in actual CAD. Furthermore, isentropic lift is rather unremarkable atop the sfc airmass, and appears unable to maintain more than a weak midlevel inversion in the face of diurnal warming/mixing. Lapse rates aren't great aloft, but mainly isolated showers have developed west of the French Broad Valley. These will continue into the evening.
Isentropic lift may slightly improve overnight but still weak. Low-level profiles do moisten across the area so cloud cover should be maintained and would appear to lower overnight, as nocturnally stronger winds near the sfc reinforce the inversion. That may be a factor in enhancing the isentropic lift as well. Generally E'ly to SE'ly flow does continue into the Escarpment, and that mechanical lift will enhance low cloud formation and likely lower vsby. Otherwise, still not seeing a strong signal for fog due to the sfc layer remaining mixed. Precip chances increase into the middle of the night, still mainly along/SE of the Escarpment.
The general pattern holds steady into Wednesday and could actually turn slightly more wedge-like. As the remnant of TS Ophelia drifts south along the coast, backing winds slightly more northerly in the midlevels, the inversion that develops tonight appears to be reinforced, such that profiles will be more stable. Morning clouds should last longer. Along with stronger CAA at the surface, this should lead to max temps a few degrees cooler than today. Although precip chances will be unmentionably small for most of the CWA, on the periphery of the "wedge" near the TN border, small SBCAPE will develop diurnally. A passing weak shortwave may trigger convection and thus 20-30% PoPs are forecast there, along with a smaller chance for thunder in the Smokies and immediate vicinity.
SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of 130 PM EDT Tuesday: Closed upper low will be situated over the Midwest and will migrate over the Lower Great Lakes and OH Valley by the end of the period and open up during this process. At the same time, Canadian high pressure over New England will continue to bring a persistent northeasterly component at the surface across the lower terrain of the CFWA. This will be the main weather headline as the surface ridging remains in place with a cool, stable airmass. Under this stable airmass will be low clouds that will stick around for a while before slowly scattering by the end of the period once the wedge weakens and upper trough axis slips east of the area. The aforementioned closed low will be morphed into an upper trough across the Northeast and Mid-Atlantic late Thursday into Friday, while a stout upper ridge intensifies across the Southern Plains and MS Valley which will help push the upper trough offshore by the upcoming weekend. 850 mb S/SE winds over the higher terrain will be enough to produce the potential for upslope shower and thunderstorm development along the ridgetops across the NC/TN border Thursday afternoon. Another round of showers and thunderstorms will be possible Friday afternoon across the NC ridgetops, this time being aided by vort energy associated with the upper trough. Mostly dry conditions with near- to slightly below-normal max and min temperatures during the short-term, with the exception of elevated PoPs in the NC mountains during peak heating both Thursday and Friday.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 245 PM EDT Tuesday: The upper trough from the short-term will slip offshore over the western Atlantic by this weekend as an amplifying upper ridge sets up shop across a good portion of the eastern CONUS. Longwave upper trough over the western CONUS and the aforementioned trough over the western Atlantic will meander in their alluded position and aid in the development of an Omega blocking pattern across much of the CONUS. This is supported by GEFS/EPS ensemble members and global model guidance, which shows the trough in the western Atlantic evolving into a closed low and meander offshore the Mid-Atlantic with some variation in position, but all in all the same idea. This would favor dry conditions across the area as the CFWA would be located on the eastern peripheral of the ridge. Despite elevated heights (590-585 dm) during the period, cool northeasterly flow will filter into the region through much of the extended as surface ridging becomes stubborn and continues to nose into the CFWA. In this case, temperatures will remain at or slightly below normal, with lows at or slightly above normal through the medium range.