textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated the aviation discussion for the 06Z TAFs.

PoP coverage and timing adjusted based on radar and latest high-res guidance.

Rainfall totals for Friday night/Saturday have decreased very slightly.

KEY MESSAGES

1. Another round of beneficial rain this morning. A cold front brings scattered showers and thunderstorms this afternoon and evening, a few of which could become strong to severe. Confidence on the severe threat remains low. Yet another round of early morning showers are possible late tonight. 2. The next active system arrives late Friday into Saturday, bringing another round of much-needed rainfall to the western Carolinas.

DISCUSSION

Key message 1: Another round of beneficial rain this morning. A cold front brings scattered showers and thunderstorms this afternoon and evening, a few of which could become strong to severe. Confidence on the severe threat remains low. Yet another round of early morning showers are possible late tonight.

Round 2 of the MCS train is approaching the area from the west at this time. While there is a large area of showers associated with it, there is less in the way of TSRA than yesterday and those may move by mostly to our south. Either way, it looks like just some additional beneficial rainfall before the showers move east of the area by late morning.

Low clouds linger through the morning but should scatter out during the afternoon as a cold front approaches from the west. Instability may be building as the clearing takes place ahead of the front. This will lead to isolated to scattered thunderstorms as the front moves through. All the guidance agrees that the better chance will be across NC. That said, some show little in the way of convection even there. With the potential for sbCAPE over NC, bulk and low level shear are high enough that a severe storm or two will be possible if the instability can develop. This is where the Marginal risk is in place, being highly conditional based on the development of any instability. Gusty winds are expected to develop ahead of the front and linger across the mountains into the evening behind the front. Gusts should remain below advisory level.

The third and final round of the MCS train makes a run at the area late tonight and Thursday morning. This system looks even weaker and farther south that this morning's MCS. Do have slight chance PoP with light QPF in the forecast during this time. No convection expected Thursday afternoon. Breezy winds linger across the mountains but taper off during the afternoon a well.

Key message 2: The next active system arrives late Friday into Saturday, bringing another round of much-needed rainfall to the western Carolinas.

Still expect surface high pressure to push into the area from the west on Thursday, ushering in cooler and drier air for the end of the week. To wit, highs on Thursday are expected to be up to a category below normal, and highs on Friday, though trending a little warmer in the new forecast, are still expected to be as much as two categories below normal. Mostly clear conditions are expected on Thursday, before a steady increase in cloud cover begins on Friday as moisture in the 700-500mb layer begins to roll in from the west.

Active weather will return Friday night. Long-range ensemble guidance is in good agreement on the expansion of a broad baroclinic zone extending across much of the southern CONUS by late Friday ahead of a shortwave ejecting out of west Texas. Associated surface frontal zone looks to stay south of the CWA through the weekend, but by midnight Friday night, ensembles variously depict either cyclogenesis over the Gulf coast or the development of an open wave along the frontal zone, prompting a round of moist upglide across most or all of the western Carolinas. The result will be another round of rainfall for the area from perhaps the predawn hours Saturday morning, through late Saturday night. As of tonight, the very wettest of LREF and NBM solutions only look to produce ~1.5-2" of QPF south of I-85, and considerably less over the northern portions of the CWA. ...drops in the bucket that is our current drought status, but at least we're headed in the right direction.

Behind this system, low-level CAA will redevelop Saturday night, and dry conditions will return for Sunday and the beginning of next week.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: A mix of VFR it LIFR cigs across the area at this time. Cigs might bounce around for an hour or so before they drop to IFR across the area as showers and a few TSRA move in with another morning MCS. Expect vsby to fall to MVFR with the precip. Have TEMPOs for LIFR cigs and IFR vsby for the precip as well. Convection should move east of the terminals be 14Z, but IFR cigs will linger only slowly lifting to MVFR then low VFR during the afternoon. A line of convection may develop, mainly for the NC terminals later in the afternoon as a cold front crosses the area. S to SW wind this morning picks up speed and becomes gusty by afternoon. KAVL will see gusty NW for the afternoon. Gusts drop off during the evening and turn northwesterly outside of the mountains but remain gusty NNW at KAVL. Yet another MCS, although weaker with less convection and restrictions, makes a run at the area late tonight. Right now, it looks like mainly VFR with spotty showers for our area.

Outlook: Mostly dry and mostly VFR Thursday into Friday before another disturbance brings rain chances and associated restrictions back Friday evening into Saturday. Dry high pressure for Sunday.

GSP WATCHES/WARNINGS/ADVISORIES

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