Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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410 FXUS62 KGSP 040553 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 153 AM EDT Thu Jul 4 2024 .SYNOPSIS... Hot and humid conditions return for the second half of the week and will linger into the weekend. Afternoon shower and thunderstorm chances return on Thursday, mainly for the mountains. A cold front will increase diurnal shower and thunderstorm chances across the entire forecast area Friday into the weekend. && .NEAR TERM /THROUGH TODAY/... As of 145 AM EDT Thursday: Another quiet night with only some high clouds dropping down from the north over the top of a few patches of lingering high-based stratocu. No changes suggested. Upper ridge over the Appalachian region will become more positively tilted as a shortwave moves south of James Bay; weak frontal zone will lay out near the Ohio River by daybreak Thursday. Sfc high will weaken further, while our low-level flow continues to veer to southwest. This flow appears less likely to foster low early-morning cloud cover than what we this morning, but should maintain an upward trend in dewpoints through Thursday, while max temps rise back to around 90 in the mountain valleys and lower to mid 90s for the Piedmont. Winds through the column will remain pretty weak. Subsidence inversion looks weaker on prog soundings but still persists such that areas near and southeast of I-85 still get below- climo PoPs for Thursday. The inversion will weaken enough that updrafts over the mountains look viable. CAMs however show only spotty QPF response in that area, perhaps reflective of winds being too weak to enhance initiation via upslope. A few vort blobs could eject from convection in KY/TN nearer the front and provide some enhancement, though. We will advertise mainly 20-30% PoPs for isolated or widely scattered coverage for most of our mountains, and higher 30-50% values along the TN border. PWATs are mostly below 1.5 inches; rainfall is not particularly likely to cause flash flooding despite slow storm motion. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... As of 120 PM EDT Wednesday: Mid level ridging will remain in place across the region through the short range period. The expected southwesterly low level flow will bring higher dewpoints back into the area. The main issue is how high the will dewpoints get. Mid 70s dewpoints are not that far away this afternoon, so they could easily advect into our forecast area. However, with the dry ground in our area we have to anticipate those readings could mix a bit lower during peak heating. Confidence is not particularly high, but the possibility of heat indices around 105 degrees exists in the lower Piedmont and around Charlotte on Friday and Saturday afternoons. Later forecast updates will have to fine tune whether this will be an issue. Otherwise, we do expect showers and thunderstorms to develop in the hot and moist air in the mountains with the highest pops being on Friday. Some storm activity will spill out into the Piedmont, but pops will be lower there. Saturday looks like another active convective day as a weak cold front drops into the area from the northwest. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 130 PM EDT Wednesday: Mid level ridging will be in place across the region with a seasonably warm and moist air mass persisting. We don`t expect excessive heat indices but do expect an active mainly diurnal shower and thunderstorm setup for Sunday through early next week. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... At KCLT and elsewhere: VFR should prevail at all terminals through the period. Only high thin clouds through daybreak for the most part, but a few high-based stratocu will also linger. Wind will be light/variable or calm until after sunrise, at which time the direction should be SW as we begin to feel the approach of the next system. Convection should not be as suppressed as the last few days, and a further increase in moisture should fuel some development of showers and storms mainly over the mtns/foothills. We start out with a PROB30 at KAVL/KHKY and will evaluate the overnight guidance to see if we can warrant a TEMPO instead. At this point, the rest of the terminals are most likely to remain dry, with only a few high stratocu. Around sunset, the wind will go light SW or variable. Outlook: Typical mid-summer humidity and diurnal convection will continue into early next week, leading to scattered TSRA and possible restrictions each afternoon/early evening. Fog and/or low stratus may develop each morning, especially for areas that received rain the previous day. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...AR NEAR TERM...AR/PM/Wimberley SHORT TERM...SCW LONG TERM...SCW AVIATION...PM