Sunrise 6:32 AM   Sunset 8:15 PM Moonrise 1:49 AM   Moonset 11:56 AM

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FXUS62 KGSP 011842 AFDGSP

Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 242 PM EDT Wed May 1 2024

SYNOPSIS
Dry and warm high pressure will continue through Thursday night, before an active frontal system moves in Friday and lingers through the weekend. Our weather gradually becomes more of a summer time pattern with afternoon and early evening storms through the middle of next week.

NEAR TERM /THROUGH THURSDAY/
As of 238 PM EDT Wednesday: All under control this afternoon across the region. Trends look good, so no course corrections.

Fair weather will persist across the region for the next 24 hours as surface high pressure camps out over the mountains, held there by an amplifying upper ridge. The ridge axis should slide to the east by the end of the day on Thursday, so the high will weaken, but the next weather system will remain too far west to affect our region. It is possible we could see another round of mtn valley fog late tonight/early Thursday, particularly in the Little TN River valley, but otherwise the sky will be mostly clear through the period. Overnight temps will be on the order of five degrees above normal. The air mass continues to modify on Thursday, allowing high temps to climb another category above today's high, topping out almost ten degrees above normal.

SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/
As of 130 PM Wednesday: Upper ridging that will have set up shop over the CFWA during the near-term will begin to breakdown and shift eastward as a shortwave trough and diffluent flow moves in from the southern/central Plains into the lower/mid MS Valley Thursday night into Friday. Weak vort energy will gradually fill in over the region and should produce enough forcing for a few showers to develop after daybreak Friday, especially over the favorable upslope regions with south-southwesterly winds filtering in better moisture. Eventually the areas of DPVA will traverse over the rest of the CFWA during the daytime period Friday, bringing with it elevated PoPs across most locations with scattered showers and a couple of thunderstorms. As of now, soundings do not support strong to severe thunderstorms as the vertical column will be fully saturated with warm air aloft and only meager instability and deep layer shear. QPF response will remain on the low end as well, outside of an embedded thunderstorm with heavier rain rates. Expect temperatures to drop a few degrees compared to Thursday for afternoon highs as extensive cloud cover and increased rain chances will be in store for much of the area.

A secondary wave of DPVA will push in soon after the initial round slips east of the CFWA. A weak attendant boundary will accompany this area of DPVA and allow for better forcing, while the environment becomes more saturated as PWAT values will rise up to 1.50" by Saturday. In this case, expect for even better coverage in rainfall, mainly by mid-morning through the afternoon as the best overlap between moisture and DPVA will occur around this time.
Profiles continue to support a very saturated vertical column, with skinny CAPE and weak deep layer shear. This may cause localized hydro concerns if the QPF response on Friday overproduces and the same locations get hit multiple times by heavier rainfall rates. The other factor going into this set up is the presence of a surface high over New England, which shifts offshore by the end of the forecast period. This set up will support the development of a weak wedge-like configuration. Temperatures will drop closer to near- normal values as a result due to cloud cover and precip locking in across the CFWA. PoPs will remain elevated through the daytime period Saturday (end of the forecast period).

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
As of 240 PM Wednesday: The flow aloft will turn more quasi-zonal with warm thicknesses still in place. At the same, a series of shortwaves traverse through the flow and allow for at least mentionable PoPs each day, especially in the mountains where topography influence will allow for daily showers and thunderstorms as we remain under a warm and moist airmass through much of the forecast period as surface high pressure shifts offshore the Southeast Coast and filters in continuous south-southwesterly low- level flow. Early next week may present better thermodynamics for stronger storms compared to the weekend as drier air aloft filters in and slightly better instability and deep layer shear will be available. Otherwise, the airmass will remain rather stagnant through the period with temperatures a couple categories above normal for highs and lows through much of the extended. The convective season will be in full swing from hereon through the Summertime.

AVIATION /19Z WEDNESDAY THROUGH MONDAY/
At KCLT and elsewhere: Not much to get concerned about over the next 24 hours, with prevailing VFR at all terminals expected. Stratocu was developing over the higher terrain, and also across the Midlands/Sandhills of the Carolinas. Expect KCLT to have FEW to SCT clouds around 050, and same at KAVL, until we lose the thermals. Wind will be light N for the most part. Clouds melt away with sunset and wind goes calm or light/variable for the overnight. Would never rule out mtn valley fog, but for now the air mass looks too dry for fog at KAVL. On Thursday, another quiet VFR day courtesy of high pressure. Wind returns from the SE around midday.

Outlook: VFR conditions are expected through Friday. More numerous showers and thunderstorms and their associated restrictions are likely on Saturday and possibly into Sunday with the passage of another cold front.

GSP WATCHES/WARNINGS/ADVISORIES
GA...None.
NC...None.
SC...None.

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