681 FXUS62 KGSP 111033 AFDGSPArea Forecast Discussion National Weather Service Greenville-Spartanburg SC 633 AM EDT Sat Oct 11 2025
.SYNOPSIS... A coastal low will lift north along the Carolina coast through the weekend. This system may bring rain to the North Carolina Piedmont and eastern Upstate late Saturday through Sunday as it passes by to our east. The low will continue to slowly track northeast along the Mid-Atlantic Coast early next week, with dry high pressure and above normal temperatures returning to the region.
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.NEAR TERM /THROUGH TONIGHT/... As of 130 am Saturday: A cyclone is forecast to gradually deepen and organize off the GA and SC coast through the period. The main impact for our area during the near term will be persistent high clouds, which will be especially thick across the eastern third or so of the CWA, resulting in max temps again falling around 5 degrees shy of normal in these areas, while near-normal highs are forecast under thinner cloud cover across the west. In terms of precip chances...while traditional operational deterministic model guidance depicts a dry scenario for the forecast area through at least the daylight hours, some convection-allowing guidance sweeps an outer band of precip originating from the Coast across the southeast third or so of the CWA this afternoon, squeezing out as much as 1/4 inch of rain in those areas by the end of today. PoPs have been increased in these areas a bit...mainly to a slight chance...but we may need to entertain higher chances with later updates if more of a consensus emerges in later guidance.
Otherwise, PoPs will increase across the east tonight, with 30-50% chances of rain forecast across the eastern part of the Upstate and the I-77 corridor after midnight. QPF will generally be in the 0.10-0.25 in these areas. Min temps will be several degrees above normal under mostly cloudy and continued breezy conditions.
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.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 1147 PM Friday: A somewhat complex synoptic pattern will be evolving by Sunday morning along the eastern seaboard. Starting aloft, a northern stream closed upper low is forecast to be located over New York state while a southern stream closed upper low is progged to be centered in the vicinity of coastal Georgia. At the surface, a coastal low is expected to reside somewhere along or just off the Carolina coast, but guidance differs with placement of the low. Some members also instigate a second area of surface cyclogenesis off the Mid-Atlantic coast as broad height falls continue to overspread a coastal baroclinic zone. The net result is a complex forecast evolution involving multiple upper waves, surface lows and a broad baroclinic zone. The overall consensus falls in line with guidance trends that support a slightly farther west track of the coastal low. The question at this point is how far west do any showers make it on Sunday. The highest rain chances continue to remain mainly along and west of the I-77 corridor, but several wetter members of guidance paint measurable rain as far west as the I-26 corridor. If these trends hold rain chances will need to be increased on Sunday, but given sufficiently different solutions will hold off on making large scale changes at this juncture. A tight surface pressure gradient will also promote gusty winds through Sunday. As for temperatures, locations under extensive cloud cover, and especially expansive precipitation, will see highs below 70 with mid to upper 70s over the western Upstate and northeast Georgia where clouds will be thinner with lower rain chances.
By Monday, the synoptic pattern will begin to change as upper ridging builds from the Southern Plains into the Mississippi Valley. This will help push upper troughing off shore with the coastal low also lifting towards New England and away from the area. This will allow for notable airmass modification as cloud cover wanes with highs returning to the low to upper 70s. Winds will also finally become less gusty as the surface pressure gradient relaxes.
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.LONG TERM /TUESDAY THROUGH FRIDAY/... As of 1208 AM Saturday: Heading into Tuesday and the remainder of the work week, guidance is in relatively good agreement that upper ridging will amplify over the Mississippi Valley while an upstream trough digs over the Rockies with a second upper low dropping over New England. The highest heights and warmest temperatures will remain confined to our west, but at least some influence from the upper ridge will dictate the forecast across the Southern Appalachians. The airmass will continue to modify with afternoon highs climbing back into the mid 70s to low 80s Tuesday and Wednesday. A slight cooldown may return late week if a backdoor front can drop into the area within broad northwest flow. Otherwise, dry conditions will prevail with scant moisture available in the column.
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.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... At KCLT and elsewhere: VFR conditions are expected to continue at the TAF sites through as least this evening, as this morning`s fog/low stratus is expected to remain confined to the mountain valleys west and north of KAVL. Moisture increasing from the east later today will result in increasing chances for lower cloud development, especially at KCLT, but these clouds will most likely be VFR in the 040-060 range. Chances for precip will also gradually increase near KCLT...mainly tonight. Some higher resolution guidance suggests a band of precip associated with a coastal disturbance may make a run toward the KCLT area this afternoon, but if anything...these guidance sources have backed off of this scenario, at least a little bit, so the precip mention is confined to a Prob30 for -RA at KCLT between 06-12Z. Lowering cigs are also expected to accompany the increasing precip chances, with MVFR expected at KCLT by 12Z Sunday. Otherwise, dry/VFR conditions are forecast at the other TAF sites, except for a brief, token MVFR visby mention at KAVL early Sunday. Winds will generally remain NE at around 10 kts through the period (lighter with vrbl direction at KAVL), with some gusts of 15-20 kts expected, especially later today.
Outlook: Periodic restrictions will remain possible at KCLT (and possibly KHKY) thru early Monday as sfc low pressure moves up the Atlantic Coast. VFR conditions are expected to return on Monday and persist thru at least the middle of next week.
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.GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None.
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SYNOPSIS...TW NEAR TERM...JDL SHORT TERM...TW LONG TERM...TW AVIATION...JDL
NWS GSP Office Area Forecast Discussion