... Above normal temperatures persist through the forecast. A weak cold front will cross the area slowly on Saturday bringing a chance for showers. Slightly cooler temperatures Sunday and Monday will be followed by a return to well above normal temperatures with the next round of precipitation possible on Thursday ahead of a strong upper low.
NEAR TERM /THROUGH TONIGHT/... As of 330 AM EDT Friday: Latest radar imagery depicts a few light showers that have developed within the past hour over the southwest mountains/northeast GA/western Upstate SC area as anticipated with available shallow moisture and upslope flow. Otherwise, conditions remain quiet across the FA this morning with a combination of passing mid to high clouds and areas of low cigs and patchy fog. Current temps are in the low to mid 60s, with a locations across the mountains slightly cooler.
With Hurricane Epsilon churning well offshore over the Atlantic, upper ridging will continue to break down over the Mid Atlantic/SE today as broad upper troughing migrates eastward across the northern Plains and into the Upper Midwest tonight. At the sfc, high pressure will continue to weaken and gradually pull away from the Carolinas as the aforementioned trough ushers a cold front towards the area - it's parent sfc low well north of the Great Lakes region by tonight. Once the morning fog dissipates within a few hours past sunrise and low stratus scatters out, expect passing high clouds through the period as moisture gradually infiltrates into the area. Light showers and a few rumbles of thunder will be possible across the mountains/TN border today while elsewhere, capping is expected to inhibit any shower activity. Though, with shallow moisture and potentially some weak isentropic lift, could not entirely rule out a light, isolated shower outside of the mountains. While a few degrees cooler than yesterday, max temps will still remain above normal today in the mid to upper 70s/near 80 degrees, cooler across the mountains.
With thunderstorm chances diminishing with the loss of daytime heating, continued shower activity will remain confined to the mountains through the overnight hours with latest guidance placing a cold front right on the doorstep of the FA around daybreak on Saturday. Elsewhere, expect dry conditions with patchy fog. QPF throughout the fcst period will remain light. Min temps will remain 10 to 15 degrees above normal.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 3am EDT Friday: For the Saturday-Sunday period, main issue will be a FROPA with some rain and some possible convection. Substantial shortwave develops in continental longwave, beginning this longwave's general eastward progression, a process that will last into midweek. The shortwave tracks up the northeast CONUS and draws a cold front into the area by late Saturday morning. Ahead of the front, continued southeasterly flow will allow Precipitable Water to creep up to about 1.5" by Sunday from the current 1" or so. Front may make slow progress through the CWA on Saturday before washing-out Sunday morning. Front will provide a focus for rain with total amounts for Sat-Sun of a tenth to a half inch. Rain amounts are not generous, but probability of some measurable rain is pretty high. Best chance for significant rain is Saturday afternoon where diurnal heating will allow some CAPE and afternoon thunder.
Temperatures on Saturday will remain well above normal with Temps Sunday declining a bit with FROPA and cloud cover, but still above normal.
LONG TERM /MONDAY THROUGH THURSDAY/... As of 3am EDT Friday: Monday through Thursday will be mostly dry, with the next good chance for precipitation coming in Thursday. Though moisture doesn't decline a whole lot after the Front washes out on Sunday, subsequent energy with the eastward progress of the continental longwave will keep well to the north with a bit of a ridge developing over the southeast states. Surface ridge to the northeast will produce some northeasterly surface winds as Cold-Air Damming with extensive cloudiness and milder temps on Monday, possibly dissipating by Tuesday. However, a strong, nearly cut-off, low forms out of the continental trough, digging into Texas by Wednesday. This system could bring some significant precipitation to the GSP area by Thursday (per the GFS) or Friday (per the EC). Currently, instability is forecast to be weak at that time, but the GFS does have some MLCAPE forecast to 400j/kg ahead of the main low Thursday afternoon, along with rather strong deep layer shear. This is a strong late-season system, bringing some chance for a round of severe weather Thursday afternoon.
Following a bit of cooling Sunday and Monday (mostly from cloud cover), well-above normal temperatures will persist until the closed low exits the region, possibly late Thursday or Friday. In addition to chances for showers and thunderstorms on Thursday, the passage of the closed upper low will give the strongest winds of the forecast, with southerly flow of 15kts at least, and higher amounts at elevation.