Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
185 FXUS62 KGSP 312145 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 545 PM EDT Thu Jul 31 2025 .SYNOPSIS... One more hot day is on tap for Friday before a cold front sags south through the region Friday night. Mild high pressure will wedge into the area this weekend bringing some much-needed relief from the heat in the form of below normal temperatures into early next week. A gradual trend back to normal temperatures expected by the middle of next week. && .NEAR TERM /THROUGH FRIDAY/... As of 5:35 PM EDT Thursday: Clusters of heavy showers and thunderstorms continue to make their way eastward across our area early this evening. Over the past few hrs, we`ve been issuing SPSs on the stronger storms, but have yet to issue any warnings. With a lack of drier air in the lower atmosphere and thus a lack of dCAPE, it`s still looking doubtful that any of these storms will become severe this evening. Regardless, the heavy rain/localized flooding threat will continue with precip water values in excess of 2 inches across our area. It remains to be seen how long this convection will linger over our CWA, but most of the recent CAM runs have it mostly ending across our area just after 00z (8 PM) this evening. The situation gets more complicated overnight as the sfc frontal zone analyzed over the OH Valley this afternoon drops down from the north and lays across our region tonight. The boundary is expected to be diffuse and may take the form of a wind shift boundary that manages to sink south of the region by daybreak while a moisture/theta-e gradient stays on the north side of the fcst area. The latter would keep warm temps overnight, then provide an environment rich with low level moisture and sfc-based buoyancy for Friday. The RAP looks reasonable with its 3000-4000 J/kg of most-unstable CAPE by afternoon and the CAMs generally fire storms over the mtns by afternoon. There should be just enough shear to maybe organize some cold pools and drive the storms off the Escarpment in the afternoon and then out across the western Piedmont. Fcst soundings suggest enough dCAPE to account for some strong wind gust threat, so the Marginal Risk on the Day 2 Convective Outlook is a decent bet. We will also still have a better chance at heavy rain and flash flooding in areas where storms might train along, especially near the Escarpment late in the day where the developing low level easterly flow is opposed by the mid/upper level westerly flow. Can`t argue with the Slight Risk in the Day 2 Excessive Rainfall Outlook either. Should be an active day. Should also be our last day of the long string of 90F or greater high temps east of the mountains. We might get close to Heat Advisory criteria again, particularly around Charlotte, but we will not entertain an advisory at this time. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... As of 115 PM EDT Thursday... Key Messages: 1) Numerous to widespread showers and thunderstorms will linger into Friday night, with isolated flash flooding possible. 2) Much cooler conditions on Saturday. The synoptic scale feature of interest remains the southward moving backdoor cold front which will push into the cwfa through Friday night. Numerous to widespread deep convection, especially along said boundary, will linger into Friday evening aided by the easterly llvl flow developing just behind the front. Within the lingering rich PWATs, there remains a broad signal, as per the 12Z HREF output, that isolated areas of excessive rainfall are probable. All systems are go for the development of an uncommon summer wedge on Saturday as sfc ridging is still progged to build sswd all the way through the cwfa. Within the NE flow, considerable cloudiness should linger all day, limiting piedmont maximum temperatures to around 80. Showers forced by the upslope and upglide remain progged to blossom, especially along the Blue Ridge where a dreary day is probable. Sfc ridge positioning changes little on Sunday, still effectively nosed into the region. Continued impingement of drier air though will lead to a higher probability of at least partial sunshine returning and a bump into the lower 80s for maximum temperatures. Sfc dwpts have the potential to dip below 60F as well, unusually dry for early August. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 155 PM EDT Thursday... Key Messages: 1) Slow climb of temperatures back to the early August normal by Thursday. 2) Gradual return to typical summertime diurnal showers and thunderstorms by midweek. Sfc ridging will linger atop the cwfa to start off the work week while upper heights and mid lvl southerly lvl flow increases around the Atlantic subtropical ridge. It looks like the weekend sfc based "cool" layer will hang on for a few more days as the llvl easterly flow keeps maximums below normal. With the influx of richer sfc dwpts on Tuesday, expect the return of more typical summertime diurnal tstm chances. The medium range model consensus drifts the weakness between Atlantic subtropical ridge and SW CONUS ridge eastward as the week wears on, likely aiding in tstms becoming numerous each day with temperatures climbing back to normal by Thursday. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/... At KCLT and elsewhere: Should be convectively active into the evening hours with plenty of buoyancy to support scattered/numerous showers and storms, which translates to all terminals having a good chance of seeing a slow-moving storm at some point thru early evening. Thus, all terminals get the TEMPO. Once the storms use up the buoyancy, it should be quiet for the rest of the night, even as a weak sfc boundary drifts in from the north. The models don`t really develop a strong enough easterly flow to force a low cloud deck in the early morning hours, so the only restrictions expected are the usual mtn valley fog/low stratus. Otherwise, a wind shift to NE is expected after sunrise. New storms should develop in the late morning to early afternoon. Only KAVL gets the mention after 16Z, and also KCLT later Friday afternoon by virtue of its longer forecast period. Outlook: A developing easterly flow Friday night into Saturday may bring widespread low cloud ceiling restrictions. The rest of the weekend looks VFR apart from the usual low stratus and/or fog each morning. A return to more usual summertime weather is expected early next week. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...CSH NEAR TERM...JPT/PM SHORT TERM...CSH LONG TERM...CSH AVIATION...JPT/PM