... High pressure dominates over the area this weekend. Moisture moving inland from the Atlantic to the southern Appalachians will produce scattered showers and thunderstorms each afternoon and evening through the weekend. A cold front will move slowly across the area on Monday before stalling just southeast of the region on Tuesday. Despite rebuilding high pressure, moisture returning over the front should lead to scattered afternoon and evening showers and thunderstorms the rest of the week.
NEAR TERM /THROUGH TONIGHT/... As of 639 AM EDT: Showers have slowly migrated to the upper French Broad valley in the pre-dawn hours, while diminishing in coverage. This trend and northward drift should continue into the middle part of the morning.
Only gradual changes are expected over the next 24 hours. The upper anticyclone generally centered over the Ozark Plateau continues to ridge in from the west, while weak sfc high pressure moving off the Mid-Atlantic coast keeps convection suppressed outside of the mtns owing to warm air at mid-levels forming a capping inversion as seen on fcst soundings. The weak upslope low level flow and differential heating should be enough to trigger scattered showers and storms over the higher terrain this afternoon/evening given available sfc-based CAPE of 1500 J/kg or so. Severe storms will be unlikely, but locally heavy rainfall might be possible with slow moving storms. Temps will be right around normal. Tonight looks like a fairly typical summer night with convective debris once garden-variety storms die off, followed by normal low temps.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 300 am EDT Saturday: Upper-level ridging remains centered over the Ark-La-Tex Region with the northeastern periphery of the ridge extending into the southern Mid-Atlantic region on Sunday. At the sfc, high pressure remains just offshore the East Coast leading to return flow off the Atlantic across the Carolinas and northeast Georgia. This will lead to continued shower and thunderstorm chances, mainly along and west of I-85. Have chance PoPs across the mountains and NC Foothills with slight chance up to and along I-85. Not expecting any severe storms with this activity as the GEFS show shear values only ranging from 10-15 knots and only a few hundred J/kg of SBCAPE across the CWA. The upper-level ridge breaks down across the Carolinas and northeast Georgia Sunday night into daybreak Monday as upper-level troughing tracks across the northern Great Lakes Region. At the sfc, a cold front will approach out of the Midwest/OH Valley region pushing towards the NC/TN border near daybreak Monday. High temperatures on Sunday will range from 1 to 3 degrees above climo across the mtns, and 3 to 5 degrees above climo east of the mtns. Lows Sunday should be 3 to 6 degrees above climo thanks to increasing cloud cover.
The aforementioned FROPA will track across the rest of the fcst area Monday into Monday night bringing much better shower coverage to the region compared to Sunday. However, QPF amounts with this front are rather disappointing with most locations picking up only half an inch of rain or less. So, this front looks to be providing little relief for the abnormally dry conditions we have in place east of the mtns. The good news is that there will be continued rain chances through much of next week. Please see the long term forecast discussion for more information. Otherwise, instability will be rather lacking with mostly cloudy skies overhead Monday, and with only 10-15 knots of shear in place across the CWA, the severe weather potential looks to remain very low, if at all. Temperatures will be noticeably cooler Monday afternoon especially across the mtns and NC Foothills where the front will push across first. High temps in these locations will end up being a few degrees below climo Monday afternoon. The rest of the fcst area will still see temps a few degrees above climo Monday afternoon ahead of the FROPA. Low temps Monday night will be near to just above normal.
LONG TERM /TUESDAY THROUGH FRIDAY/... As of 320 am EDT Saturday: The cold front mentioned above looks to stall from the Gulf Coast to the Southeast Coast throughout the duration of the long term forecast period. As a result, the majority of global model guidance has shower and thunderstorm chances continuing across the fcst area through late next week. This could act to alleviate the abnormally dry conditions east of the mtns. However, guidance is not in good agreement regarding how far NW shower and thunderstorm chances would make it. So, for now the southeastern zones look to have the best chance to see continued PoPs. Capped PoPs through the long term to chance due to model discrepancy. With the front stalling out, cloud cover looks to hang around throughout the fcst period leading to noticeably cooler and below climo high temps, especially on Tuesday and Wednesday. Tuesday temps look to drop around 10 degrees below climo with mid to upper 70s east of the mtns and mid 60s to lower 70s across the mtns. Wednesday high temps increase slightly, but remain 3 to 5 degrees below climo. High temps Wednesday look to only top out into the mid 80s east of the mtns and lower 70s to lower 80s across the mtns. So, it will be feeling a lot more like mid May than late June middle of next week. Temps continue warming late week as upper-level ridging builds back into the region from the west. This will allow temps to return to near climo values. Lingering overnight cloud cover will lead to mostly near to above normal low temps throughout the long term.