textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

No significant changes to the forecast with this forecast package.

Updated the 06z aviation forecast.

KEY MESSAGES

1. A cold front will bring spotty showers, and possibly a thunderstorm, this afternoon and evening. Warm and dry weather returns late week into the weekend.

DISCUSSION

Key message 1: A cold front will bring spotty showers, and possibly a thunderstorm, this afternoon and evening. Warm and dry weather returns late week into the weekend.

Early morning water vapor imagery depicts a positively tilted trough sliding across the Midwest towards the Ohio Valley while surface analysis places an attendant cold front Chicago to central Missouri. Guidance is in good agreement that the trough will take on a neutral tilt as it swings across the Appalachians today with the cold front approaching the mountains this afternoon. The frontal boundary will push across the area late this afternoon through the evening hours. Forcing for ascent will be modest, but the antecedent airmass is rather dry with PWATs 1" or less. This will leave the system at least somewhat moisture starved with the trough orientation not supportive of sufficient moisture return prior to the arrival of the front. Nonetheless, a band of moisture pooling ahead of the boundary should support the development of a fast moving band of showers with a couple embedded thunderstorms over east Tennessee. This line will enter the mountains mid to late afternoon and across the foothills and Piedmont this evening. Coverage of showers, especially east of the mountains, may be rather limited with widely scattered showers. The front will also be moving fast enough that locations that do see rainfall aren't expected to see any appreciable values that would ease drought conditions, unfortunately.

Thereafter, a tall upper ridge is progged to slide east across the Mississippi Valley and into the Appalachians where it will flatten late week into the weekend. This will support rising heights and warming temperatures with afternoon highs climbing back into the upper 80s to low 90s. At the same time, a deep western trough digs across the Great Basin through the weekend with broad downstream southwest flow draped across much of the Great Plains. Eventually, this may support some degree of moisture return back into the Southern Appalachians while embedded shortwave perturbations lift out of the Mississippi Valley into the Ohio Valley. The majority of any QPF response remains displaced off to our west and north, but isolated to widely scattered convection cannot be completely ruled out late in the period.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: Not much change from the 06z TAF issuance. VFR conditions expected thru the period. A weak cold front will bring a narrow, broken line of showers into the mountains, and possibly surviving into the NC Piedmont late aftn thru this evening. Confidence remains low on much, if any impacts, these may have on KAVL, KHKY, and KCLT. But high-res models are in decent agreement on the timing, and PROB30 groups for SHRA lines up with that. Otherwise, winds will be light thru the morning, then pick up out of the SW winds will pick up and become marginally gusty in the Upstate. Winds will toggle to W, then NW behind the front this evening, becoming gusty at KAVL due to channeled up-valley flow. Breezy N/NW winds expected at KCLT starting late Thursday morning.

Outlook: VFR and quiet weather is expected for the rest of the week. Moisture begins to increase out of the south over the weekend, but confidence on a return to any diurnal convective rain chances remains low.

GSP WATCHES/WARNINGS/ADVISORIES

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