textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Update for 12z TAFs.

KEY MESSAGES

1. Dry through Saturday before rain chances return late this weekend into early next week. Temperatures remain mostly above normal, with the exception of Sunday.

DISCUSSION

Key message 1: Dry through Saturday before rain chances return late this weekend into early next week. Temperatures remain mostly above normal, with the exception of Sunday.

Mid/upper ridging gradually breaks down through tonight as the flow aloft becomes more quasi-zonal through the end of the workweek. Strong surface high (1030+mb) centered over the northeast CONUS slips offshore today, while continuing to nose into the CWA Thursday and Friday. Expect this surface high to control the sensible weather through Friday as dry weather continues. Temperatures are expected to remain at or a few ticks above normal for this afternoon and continue to rise through the rest of the workweek with values around 5-10 degrees above normal Thursday and Friday.

Synoptic pattern amplifies by this weekend as a mid-level shortwave trough develops over the Southern Plains Thursday into Friday. At the same time, a backdoor front slips into the region from the north Saturday, which will support the onset of cold air damming as a reinforcing continental surface high (~1030mb) moves from south-central Canada into the northeast CONUS. Weak isentropic lift should help to develop better precip chances Saturday night into Sunday as a classical CAD locks in and associated forcing for ascent from the shortwave traverses across the area. Guidance vary on the duration and QPF amounts as most of the guidance handle the shortwave differently. The stronger the shortwave, the better forcing will be available and help to squeeze as much of the available moisture as possible and vice versa. As a result, forecast confidence on exact timing and QPF amounts remain low. CAD becomes more in-situ as we head into early next week as the surface high slips offshore and weakens, while the aforementioned shortwave lifts north and east of the region. Lingering PoPs can't be ruled out next Monday and Tuesday as temperatures are likely to trend slightly cooler compared to the current forecast as any clear cut wedge erosion mechanism isn't very obvious in model guidance. Model guidance continue to hint at a stronger closed upper low over the central CONUS just beyond the current forecast period that will need to be monitored over the next week or so. Temperatures will drop at or even below normal by Sunday and likely struggle to rise above normal early next week.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

For KCLT: Easterly low-level flow will support low stratus moving inland from the NC coast early this morning, and while a cig appears unlikely, the deck could get close enough to warrant a FEW012 mention this morning; furthermore very low diurnal cumulus formation could occur through mid-morning. Those clouds should dissipate for a time, but low VFR cumulus again may form during the afternoon. Moist onshore flow tonight into early Wed appears even more capable of forming stratus than this morning, and making another run at the field. Think clouds may be depicted too low in guidance as usual in this sort of regime, however, so introduced a VFR cig at 11z Thu and only SCT MVFR level mention, which potentially will linger much of the day Thursday.

Otherwise: Another dry TAF period. Cirrus will be seen early this morning, and most likely all TAF sites remain VFR through evening; a few cumulus may be seen this afternoon. Mainly light N to NE winds, except ESE to SE at KAVL due to terrain effects. The onshore/easterly flow is expected to bring low VFR cigs to KGSP/KGMU/KAVL before dawn Thu and MVFR to KHKY.

Outlook: Dry through Saturday. Restrictions which develop Thu morning should improve by afternoon. However, mountain valley fog/low stratus may develop each night. Rain returns late Saturday night into Sunday, bringing restrictions back to the terminals.

GSP WATCHES/WARNINGS/ADVISORIES

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