069 FXUS62 KGSP 060739 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 339 AM EDT Mon Sep 6 2021 .SYNOPSIS... A weak cold front will move through the forecast area today bringing isolated to scattered showers to the region. Another cold front is expected to cross our area late Wednesday and bring more showers and possibly a few thunderstorms. Drying high pressure will spread back over the region in the front's wake and linger into the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 310 AM: A broken line of showers ahead of a cold front is moving across the area early this morning. Best coverage will be the I-40 corridor and the NC southwestern mountains into NE GA and the western Upstate. Precip has been on the light side and this is expected to continue, although moderate QPF is possible in any heavier showers. Precip chances diminish across the I-40 corridor and northern mountains after daybreak as the front drops into the area and drier air moves in behind. The front is quite slow moving, so precip chances will continue along the front. The highest precip chances will be across NE GA and the western Upstate where moisture and forcing lingers longer. Precip chances taper off across the NC southern Mountains, southern foothill, and Southern Piedmont. Guidance shows the best chance of instability will be across NE GA and the western Upstate where moisture pools and the subsidence inversion erodes enough for weak instability to develop. These locations have the best chance to see a thunderstorm. QPF still looks to generally be light, but moderate values are possible in heavier showers and thunderstorms. Highs will be near or just below normal. The front pushes south of the area this evening with convection quickly tapering off with loss of heating and drier air moving in. Should see a return of mountain valley fog, with patchy fog elsewhere. Lows will be near or just below normal. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 315 AM EDT Monday: The short-term fcst picks up at 12z on Tuesday with upper trofing lifting off the coast of Maine as another upper trof begins to dig down over the Western Great Lakes and broad upper ridging remains in place over the Western CONUS. Over the next couple of days, the trof will dig farther southward and is expected to be centered just to our north by the time the period ends early Thursday. At the sfc, a weak cold front will be nearly stalled just to our south and east by early Tuesday, as high pressure spreads farther eastward and over the western Carolinas. Some degree of weak, SLY return flow is still expected to develop over the CWA Tues afternoon as high pressure shifts more NE. This will allow whatever is left of the frontal bndy to drift back northward and bring more moisture into the CWA from the south. On Wednesday, another cold front will approach the area from the NW and move thru the CWA late Wed into early Thurs. Overall, the models have been slowing the progression of this front and it's now not expected to be clear of the CWA until later Thurs morning. Overall, precip chances and amounts haven't changed much from the previous fcst, with the best chances for more widespread precip Wed aftn/evening and PoPs ramping down early Thurs as the front moves east of the CWA. Temperatures start out just above normal on Tuesday and remain a few degrees above normal thru the period. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 255 AM EDT Monday: The extended fcst picks up at 12z on Thursday with another broad upper trof centered to our north and gradually moving eastward as steep upper ridging dominates the Western CONUS. The upper trof is expected to linger over the Eastern CONUS thru the end of the week, with heights likely recovering at least some over the weekend as the upper ridge deamplifies and spreads farther east. At the sfc, another cold front will be moving south and east of the CWA with broad high pressure spreading over the area in its wake as the period begins early Thurs. At the same time, low pressure will try to organize over the northern Gulf of Mexico and lift NE and over the Big Bend of Florida. The models appear to be coming into better agreement wrt how quickly the low will progress NE, with most of the guidance moving it off the Southeast Coast late Friday or early Saturday and broad high pressure remaining over our area for the rest of the period. Temperatures start out near normal on Thursday and gradually warm above normal over the weekend. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... At KCLT and elsewhere: SHRA and low VFR cigs moving into the mountains ahead of a cold front. VFR cigs and isolated SHRA will spread across the foothills and Piedmont early this morning. MVFR vsby and cigs develop across the mountains as low level moisture fills in. The front drops across the area after daybreak turning the SW wind to NW. Lingering moisture and instability along the slow moving front will keep low VFR cigs and isolated showers for KCLT and KGSP/KGMU into the afternoon. Instability and moisture is better near KAND, so a PROB30 for TSRA included there. Low clouds scatter out behind the front with winds turning briefly SE then back to N for the evening. Outlook: Nocturnal Piedmont restrictions cannot be ruled out late tonight with front stalling just south of the region. A few SHRA/TSRA may redevelop Tuesday afternoon. A second cold front may bring scattered convection Wednesday into Thursday. Mountain valley fog and stratus remain possible each morning. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JPT NEAR TERM...RWH SHORT TERM...JPT LONG TERM...JPT AVIATION...RWH