textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Guidance is backing off on the potential for light snow reaching the North Carolina mountains today.

KEY MESSAGES

1. Cold air mass lingers over the region through tonight, keeping well below normal temperatures around. Lows tonight will drop near to below freezing, impacting sensitive vegetation that has already started blooming from the recent abnormally warm weather. 2. Warming trend still on track starting Thursday into weekend. A backdoor cold front still could bring showers on Monday and cooler temps on Tuesday.

DISCUSSION

Key message 1: Cold air mass lingers over the region through tonight, keeping well below normal temperatures around. Lows tonight will drop near to below freezing, impacting sensitive vegetation that has already started blooming from the recent abnormally warm weather.

Upper troughing remains overhead while periodic shortwaves dive down across the western Carolinas and northeast Georgia through tonight. Meanwhile, at the surface, cool high pressure will remain over the region keeping dry conditions and well below normal temperatures around.

00Z CAMs are backing off on the potential for light snow over the North Carolina mountains today. Even if snow were to survive this far east it would likely sublimate before reaching the ground with such a dry air mass in place. Upper cloud cover will continue to increase through daybreak before thinning out late this morning into this afternoon for most locations. However, cirrus should gradually thicken again across the mountains, especially along the NC/TN border, this afternoon and evening. Light winds finally return today and will linger through tonight. Lows tonight will fall near to below freezing, with freezing temperatures most likely returning in the North Carolina mountains and along/north of I-40 with the NBM showing a 70% to 100% chance of freezing temperatures across these locations. Elsewhere, the NBM only shows a 45% to 65% chance of freezing temperatures returning. Sensitive vegetation that has already started blooming from the recent abnormally warm weather will remain vulnerable with the return of cold temperatures tonight.

Key message 2: Warming trend still on track starting Thursday into weekend. A backdoor cold front still could bring showers on Monday and cooler temps on Tuesday.

A series of short waves move through the northwest flow over the area. This brings a series of clipper lows across the Mid Atlantic. Guidance continues to differ from run to run and from each other on how close these lows make it to our area, and any resulting moisture and precip. The model blend keeps the area dry which is reasonable given the uncertainty.

The bigger story is the steadily rising heights through the weekend leading to a significant warming trend. Temps near normal on Thursday rise into the 80s by Sunday, around 20 degrees above normal.

Guidance in better agreement on a backdoor cold front moving in on Monday, bringing a chance of rain. That said, they do differ on what the front does for Tuesday. The GFS moves the front to our south with dry, CAD high pressure building in. The Canadian and ECMWF stall the front with a wave of low pressure moving along it keeping precip, and a wet, CAD high pressure building in. The model blend has chance PoP developing, and this also seems reasonable given the overall trends. Temps monday drop to around 10 degrees above normal then 5 to 10 below normal for Tuesday. Temps both days will be highly dependent on the development of precip.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: VFR and dry, with light winds through the 06Z TAF period. Winds will start out N/NNW at KAVL before going calm later this morning. Winds east of the mountains will start out N/NE east of the mountains, turning more E'ly through daybreak. Winds will turn S/SE across all terminals late this morning into this afternoon before going light and VRB to calm shortly after sunset.

Outlook: Mostly dry and VFR through the rest of the week.

GSP WATCHES/WARNINGS/ADVISORIES

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