Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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611 FXUS62 KGSP 070231 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 1031 PM EDT Mon May 6 2024 .SYNOPSIS... A summerlike weather pattern remains through mid week with mainly afternoon and early evening showers and thunderstorms. Temperatures will be well above normal Tuesday through Thursday. Showers and thunderstorms will be more numerous ahead of a strong cold front which will cross our region Thursday night and Friday. Expect drier and cooler weather for the weekend. && .NEAR TERM /THROUGH TUESDAY/... As of 1030 PM EDT Monday: Scattered showers and thunderstorms continue across the SC Upstate and far northern NC Piedmont this evening. There is also a line of storms pushing across the TN valley as of the writing of this AFD. This activity has prompted a several severe warnings and SPS` this evening, mainly for hail near quarter size, which stands to reason given the icy cores but not-so- impressive DCAPE values across the area. With 500-1,000 J/kg of MUCAPE and 20-30 kts of 0-3 km shear remaining in place across the forecast area this evening, strong to severe storm threat will continue through at least the next few hours as activity progresses eastward.Heavy rainfall and frequent lightning will accompany any storms that develop. Did increase PoPs along the NC/TN border, the central SC Upstate, and the northern tier of the CWA to likely to categorical over the next few hours to account for thunderstorm activity. Otherwise...as flow turns NW aloft this evening, CAM guidance continues to depict additional waves of scatter showers and thunderstorms through tonight...which should fizzle as instability wanes. The latest couple runs of the HRRR now bring a semi-organized line of cells across the mountains, with some redevelopment over the western SC Upstate after midnight. If that happens...instability will be minimal but nonzero, and shear will remain elevated...such that a stray strong to severe storm couldn`t be ruled out. Low temps early tomorrow will be roughly 10 degrees above climatology again. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... As of 215 PM EDT Monday: A flat upper ridge will be in place across the area Wednesday with weak short waves rippling through the flow and across the area. A stronger short wave crosses the area early Thursday as an upper low moves into the Great Lakes. At the surface, a weak east/west oriented front stalls over the area Wednesday, with a cold front moving in from the west on Thursday. The air mass becomes very unstable Wednesday with moderate shear and mid level dry air leading to increased DCAPE and sfc delta Theta-E values. Coverage will be higher across the mountains, but severe storms will be possible at any location across the area given these parameters. Moisture increases on Thursday with less mid level dry air, DCAPE, and sfc delta Theta-E values. Instability also falls, but could remain in the moderate range while shear increases, approaching strong territory. Convective coverage still favors the mountains, but at least likely PoP will be featured across the area. Severe storms will again be possible, but overall chance is more uncertain. Highs Wednesday will push 90 degrees outside of the mountains, and mid to upper 80s in the valleys then fall a few degrees Thursday. Lows will be well above normal as well. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 240 PM EDT Monday: The Great Lakes low opens into a trough which moves into the area Friday. A series of short waves keeps the general troughiness over the eastern CONUS through the end of the period. With the trough moving in on Friday, cyclogenesis takes place near the Carolina coast along the cold front that moves through on Thursday. Guidance keeps going back and forth on the location of the front and cyclogenesis, along with any lingering moisture and resulting precip. Have continued the trend of chance PoP for now given the uncertainty. A series of weak clipper-like low pressure centers of frontal systems move near or over the area through the rest of the period. This leads to isolated to possibly low end scattered showers for the mountains each day with dry conditions elsewhere. Temps fall to a few degrees below normal by Saturday, then rise back to near normal through the end of the period. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... At KCLT and elsewhere: Convection is underway across the SC Upstate and parts of the NC mountains. Most model guidance doesn`t bring this activity to KCLT directly, although some lingering showers could certainly make it in the next 1-2 hours. Some guidance depicts a round of showers and embedded thunderstorms arriving from the west around and after midnight, but should this develop it would mainly affect KAVL and the Upstate terminals. IFR VIS and CIG restrictions are expected again tonight, with the worst VIS expected for the mountain sites and the worst CIGs expected virtually everywhere. This should scatter out quickly after daybreak Tuesday, followed by prevailing VFR through the end of the period. Some additional convection is possible in the afternoon, but mostly looks to stay confined to the NC zones...and may not even escape the mountains. Outlook: Moist profiles will combine with a weak/stalled front thru the mid-week, resulting in a period of active, mainly diurnal convec- tive weather each day. There is potential for restrictions associated with widespread fog and/or low clouds each morning. A cold front moves in later in the week with continued chances of diurnal convection. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...DEO NEAR TERM...AR/JPT/MPR SHORT TERM...RWH LONG TERM...RWH AVIATION...MPR