428 FXUS62 KGSP 081030 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 630 AM EDT Fri Oct 8 2021 .SYNOPSIS... Upper level low pressure moves into the Great Lakes today but periods of widespread showers and locally heavy rainfall are still possible. Moisture lingers over the area Saturday as a surface low pressure center moves north along the Carolina Coast. Dry high pressure builds in on Sunday and remains in place through next week with warming temperatures. && .NEAR TERM /THROUGH TONIGHT/... As of 6:30am EDT Friday: Light to moderate showers currently over the southwest quadrant of the CWA. These are expected to increase in coverage to the north and east through the day. A negatively-tilted upper trough lies west of the area and will finally eject northeastward today. Surface low with this system lies off the coast of South Carolina currently, and will make gradual progress northeastward. This will give fairly steady, though light to moderate, easterly to northeasterly surface winds. Rainfall is expected to be enhanced in upslope areas of the Southern Appalachian, particularly along the escarpment zone adjacent to the foothills. Precipitable water levels at around 1.5", while not extreme, are elevated for this time of year, and passage of upper system will provide ample upper lift to wring-out moisture. Additional rainfall amounts today of 1 to 2 inches are possible in some areas today, which will fall on very saturated soils, thus continuing the threat of flooding. Surface CAPE levels are minimal early this morning, and showers on radar are quite shallow. With a little warming after daybreak today, sufficient sbCAPE should develop to support thunder storms as the main form of rain. Rain and thunder will begin to end from West to East across the region this evening as upper system ejects northeastward, and surface winds become more northerly. Rain and clouds will keep temperatures moderate, with a muted diurnal range, and with highs only warming 5 degrees or so above the overnight lows. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 250 AM Friday: A wave rotating around the departing upper low will close off into its own upper low off the Carolina coast Saturday. This low will slowly open up and move up the East Coast Sunday as an upper ridge axis move over our area from the west. This feature interacts with an elongated area of surface low pressure off the South Carolina coast. The low initially has potential for tropical development but interaction with the upper low keeps it from fully developing tropical characteristics. Still, the low does strengthen and moves slowly toward Cape Hatteras through Saturday night, across or near the Cape Sunday then toward the Virgina coast Sunday night. A moist easterly flow around the low will bring keep low level moisture and weak instability over at least the eastern portion of the CWFA Saturday leading to scattered showers and isolated thunderstorms. Most of the guidance shows the flow turning more northeasterly then northerly Saturday night into Sunday night. This will bring drier air and a suppressing subsidence inversion into the area. There is some guidance showing lingering low level moisture and more easterly flow during this time. A guidance blend keeps the area dry, after some lingering showers Saturday evening. Therefore, have continued the dry forecast. Highs near normal Saturday rise a few degrees above normal on Sunday. Lows remain nearly steady around 5 degrees above normal. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 130 AM Friday: Most of next week looks benign, but seasonally warm, with a positively-tilted upper ridge in place on Monday that gets reinforced on Wednesday. One system will lift northeastward across the upper Midwest on Tuesday and some of the model guidance responds with isolated showers over the mtns, but at this point the possibility seems too remote to mention. Temps will be on the order of 5 deg above normal through most of the period...more like mid September. The pattern will start to become more progressive late in the week, with the upper ridge axis moving offshore and a broad upper trof pushing a weak front toward the fcst area from the west on Friday. That will finally bring a small precip chance into the western zones for the end of the week. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... At KCLT and elsewhere: Rain, low clouds, and reduced visibility will continue around the area through Friday, with MVFR to LIFR conditions at times. Ceilings of 500FT AGL are currently widespread with little improvement expected before 18Z. Wind direction will be fairly steady from the northeast as surface is parked off the South Carolina Coast, with speeds of calm to 10kts. Early this morning, Convective instability levels are minimal and area of scattered showers well to the west of KCLT and I77, are not expected to produce any lightning. Showers are expected to spread over most areas after day break today, with thunder becoming more likely in the afternoon. Outlook: Finally, some drier air will try to work in from the west over the weekend. Conditions will return to prevailing VFR beginning on Saturday morning. Low-level moisture may linger, keeping a chance of low cigs and fog, especially late night/early mornings. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...Flash Flood Watch until noon EDT today for GAZ010-017-018-026- 028-029. NC...Flash Flood Watch until noon EDT today for NCZ033-049-050-052- 053-059-062>065-501>510. SC...Flash Flood Watch until noon EDT today for SCZ001>005-010-011- 019. && $$ SYNOPSIS...CAC NEAR TERM...WJM SHORT TERM...RWH LONG TERM...PM AVIATION...WJM