textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

The aviation forecast was updated to reflect the recent 00Z TAF issuance.

KEY MESSAGES

1. Unseasonably warm and humid conditions are expected for the remainder of the week, with shower and thunderstorm chances increasing Wednesday and lingering through Friday.

DISCUSSION

Key message 1: Unseasonably warm and humid conditions are expected for the remainder of the week, with shower and thunderstorm chances increasing Wednesday and lingering through Friday.

Widespread cloud cover is in place across the area this evening as deepening moisture continues to stream into the area embedded within ESE flow across the Southeast. There's no evidence on radar of any ongoing drizzle, although some very shallow, isolated sprinkles can't be ruled out, particularly along the Blue Ridge Escarpment.

Otherwise...the upper level pattern across the CONUS will remain amplified and not especially progressive through much of the week, with a fairly short-lived omega block persisting over the next few days out west. The center of an upper low is expected to lift from the Southern Plains to the upper MS Valley by Wednesday morning, inducing gradual height falls over the Eastern CONUS. An associated occluding/weakening frontal zone is fcst to approach our CWA from the west on Wednesday. Persistent SLY flow ahead of this feature will result in increasingly warm and humid conditions over the next couple of days, with temps expected to be at least 5 to 10 degrees above normal while sfc dewpts are expected to reach the 60s by Wed aftn. The frontal zone should have more than enough moisture along with some modest instability in place as it moves into our area Wed aftn/evening. Short-term guidance still shows fairly robust forcing, especially in the low levels as the boundary crosses the TN Valley and the Deep South Wed aftn, but this weakens as it moves into our area Wed evening. As a result, a notable gradient in PoPs and especially QPF is anticipated from west to east, with roughly 0.5 to 1.0" amounts currently fcst across our western third (with locally higher amounts on south-facing slopes), and less than 0.25" expected over the I-77 corridor. In addition, the combination of fairly weak shear and modest instability along with the occluding nature of the front are not favorable for an organized severe storm threat. Regardless, a few strong-to-severe storms cannot be ruled out. Locally heavy rain is possible across our western zones, especially on aforementioned south-facing slopes, with a non-zero chance of localized flash flooding Wed/Wed night.

Little temperature contrast is anticipated in the wake of the frontal zone on Thursday, so conditions are expected to remain warm and humid. Broad cyclonic flow aloft combined with terrain effects is likely to result in some sct convection Thursday aftn/evening. By Thursday night, a weakening upper low over the Southern Plains is fcst to move quickly across the SE quadrant of the CONUS, with the associated height falls bringing another cold front to our area, and possibly another round of sct convection on Friday. At this time, most of the guidance has better coverage/higher PoPs over our eastern zones. Saturday should be mostly dry with temperatures remaining above normal and some amount of cooler/drier air advecting into our area. By Sunday, temperatures and humidity levels should return to near-normal for early Nov.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: Our streak of quiet aviation weather finally comes to an end over the next 24 hours as an active system approaches from the west. All the TAF sites are currently VFR, but quite a bit of cloud cover is in place, with mostly BKN/OVC stratocu and some thick mid-level clouds. Guidance is in good agreement, however, that as deeper moisture pushes into the area overnight, most terminals will see at least MVFR ceilings before daybreak, with some potential for IFR cigs leading up to dawn. Thereafter, thick cloud cover embedded within strengthening SE winds will result in MVFR to IFR restrictions persisting for much of Wednesday. Some low-end gusts may develop, particularly at KCLT, and possibly the Upstate sites as well. Some improvement late in the day will be brief, if it occurs at all, as scattered showers, and perhaps even a couple of embedded thunderstorms, arrive in the western zones by around sunset. Scattered showers will then persist across the area for much of Wednesday night, resulting in widespread patchy fog and lingering low ceilings through the end of the 00Z TAF period and beyond.

Outlook: Showers and associated restrictions will persist into at least early Thursday, as a cold front arrives in the region. Consistent improvement is not expected until Friday, when the cold front moves to our east and ushers in VFR conditions for the weekend.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...None. SC...None.