Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
543 FXUS62 KGSP 072358 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 758 PM EDT Mon Jul 7 2025 .SYNOPSIS... Hot and humid conditions continue through midweek featuring daily afternoon and evening shower and thunderstorm chances. The heat abates somewhat into the weekend but daily afternoon and evening shower and thunderstorm chances continue. && .NEAR TERM /THROUGH TUESDAY/... As of 736 PM Mon: A few showers and storms were making the most of the environment to the south and west of the Charlotte metro area early this evening, where a relative CAPE minimum was located. Nevertheless...there they are. Will add in a small chance of showers for the next hour or two until sunset, when the shower activity should be dissipated. Temps were in good shape. Otherwise...as post-TC Chantal moves up the mid-Atlantic coast thru the evening, it is progged to be absorbed into a weak sfc low centered in Ontario. A subtle cold front extends southwest from the aforementioned sfc low into the mid-Mississippi Valley. A trough moving across the northern Plains will help push the frontal features slowly eastward by Tuesday. A sfc trough looks to remain east of the Appalachians. While the front itself remains to our west through peak heating Tue aftn, some degree of moisture pooling ahead of it leads to higher PWATs and more midlevel moisture, both of which make profiles more favorable for deep convection. The rest of the pattern remains pretty similar to today. PoPs accordingly tick upward such that 40-60% PoPs will be advertised over the mountains, decreasing to 20-30% over the Piedmont. SPC continues to highlight our eastern zones in Marginal Risk for damaging wind on account of wet microburst potential associated with heavy water loading and 2000+ SBCAPE in the afternoon. It could be argued the severe potential will extend across more of the CWA, although such storms are likely to remain isolated, and marginal-level risk is appropriate. Temps will rise slightly warmer into the upper 90s across much of the Piedmont, but thinking is that aftn mixing still will bring dewpoints low enough to limit heat index to 100-104 in most locations, so Heat Advisory does not look warranted. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... As of 200 PM Monday: A shortwave will propagate into the OH and TN valleys on Wednesday, resulting in height falls over our area and slightly lower thicknesses. Its proximity will enhance forcing across the area as diurnal heating supports SBCAPE of 1000-2000 J/kg. Categorical PoPs exceeding 75-80% are forecasted across the mountains and NC Piedmont, with likely PoPs of 60-75% over much of Upstate SC and the GA Piedmont, where profile guidance suggests a deeper mixed layer, higher LCLs, and subsequently lower surface-based instability. Bulk-shear values increase slightly ahead of the trough but generally speaking, values are not supportive of organized convection. However, profile guidance suggests that there will be sufficient mid- and upper-level dry air to support isolated damaging microbursts. PWs of 1.6-1.8" and fairly unidirectional low- and mid-level flow support some cell training capable of producing isolated areas of excessive rainfall. The suppression of the subtropical ridge and increased cloud cover should reduce high temperatures a few degrees, though most areas will likely peak at slightly above-normal temperatures even if rain-cooled outflow arrives later in the afternoon. While afternoon mixing is expected to lower dewpoints a few degrees in the afternoon, heat indices will likely approach the 100-103 range in favored areas of the Savannah River Valley and the CLT metro. With strong subtropical ridging in place over the Sargasso Sea/western Atlantic and shortwave ridging over the Great Lakes, there will be little eastward progression or deamplification of the shortwave trough located just to our west over the TN Valley. As such, expect similar unsettled weather and convective coverage Thursday afternoon and evening. Increasing moisture through the column given persistent SWly flow and favorable storm-motion vectors suggest a continued risk for isolated areas of excessive rainfall. Bulk-shear values increase a bit further, approaching 20kts, and despite tall and skinny CAPE profiles, a wet microburst threat will continue where the strongest updrafts can develop. High temperatures will fall a few degrees further compared to Wednesday given thicknesses, cloud-cover, and convective coverage, but this will only equate to highs near normal for mid-July. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 200 PM Monday: The extended period will remain active as we are generally sandwiched between subtropical ridging along the Gulf Coast and the southern extent of the westerlies, which will usher in rounds of weak shortwaves across the OH and TN valleys and over the central and southern Appalachians through the period. This pattern will support likely to categorical PoPs over the mountains and foothills with chance PoPs over the Piedmont each afternoon and evening. Low-level moisture will continue to pool across the area with flow taking a circuitous route from the western Gulf of America, around the persistent Gulf Coast ridge, and into the southern Appalachians; therefore, typical periods of heavy rainfall can be expected, with isolated areas of excessive rainfall possible. Parameters are not supportive of a notable severe weather threat any afternoon, with the typical isolated damaging wet microburst being the primary concern. High temperatures will also remain fairly stable at near-normal values, with upper 80s in the mountain valleys and lower 90s across much of the Piedmont. Overall, pretty typical July weather is expected. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... At KCLT and elsewhere: Isolated showers and thunderstorms continue across the region at issuance time, but for the most part too far away from the terminals to include in the forecast. After the shower activity diminishes at sunset, should be a quiet night with only light/variable wind and some thin cirrus overhead. Mtn valley fog is not expected. On Tuesday, some moisture pooling along a boundary will allow for better coverage of thunderstorms in the late afternoon and early evening. Will handle this with a generic PROB30 at all sites other than KAND. Wind should be light SW and clouds limited to scattered cu with high bases, apart from thunderstorms. Outlook: Typical summertime weather is expected thru late week, with sct to numerous SHRA/TSRA mainly in the aftn/evening and fog and/or low stratus possible each morning. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JMP NEAR TERM...PM/Wimberley SHORT TERM...JMP LONG TERM...JMP AVIATION...PM