Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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488 FXUS62 KGSP 240753 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 353 AM EDT Fri May 24 2024 .SYNOPSIS... Temperatures will remain several degrees above normal each day through the holiday weekend. Daily chances for showers and thunderstorms. A cold front on Monday brings cooler and drier conditions for the middle of next week. && .NEAR TERM /THROUGH TONIGHT/... As of 325 AM EDT Friday: Still dealing with scattered showers and thunderstorms over the western Piedmont of NC at this early hour, but these should move to the east of the fcst area by 09Z or so. Meanwhile, other showers were noted also moving along to the east. The SPC mesoanalysis shows a residual most-unstable CAPE around 500 J/kg, so additional showers or maybe even a thunderstorm or two won`t be ruled out through daybreak, but for the most part the coverage should be in a lull through the mid-morning. Expect a few patches of fog across the region where precip has moved through overnight, along with mild temps. The main problem for the next 24 hours or so revolves around deep convection, and there aren`t any easy answers, because the CAMs don`t show much agreement in terms of coverage, timing, and intensity. In reality, new development of showers and storms will probably be tied to the approach and passage of remnant MCVs and outflows from storms out west. These may come in a few waves in the otherwise quasi-zonal flow, but when they pass through, will help to trigger or bring an uptick in coverage of storms. With that, also perhaps an increase in potential for severe storms. The environment will remain somewhat favorable with sufficient buoyancy on the order of 1500-2500 J/kg of sfc-based CAPE depending on the model, and enough deep layer shear through the early evening on the order of 20-30 kt, which could make storms more interesting. No issues with the Marginal Risk on the Day 1 outlook and it seems reasonable to expect a few warnings to be issued mainly in the afternoon/evening. Similar to this past evening, expect some of this activity to persist into the early morning hours as the buoyancy is slowly used up. Won`t rule out locally heavy rain, either. High/low temps will be about five degrees above normal. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... As of 215 AM Friday: Picking up Saturday with gradual strengthening of an area of high pressure over the Gulf and a weak ridge extending northward over the CWA. As the ridge progresses eastward, shortwaves traverse the Carolinas and up the chances for additional showers and thunderstorms. Guidance keeps a steady stream of moisture in the area through the forecast period and beyond, with instability remaining prevalent. Latest guidance does bring some questions as far as coverage on Saturday, especially outside the mountains. EURO is trending for a few more areas outside the mountains, but the GFS trends drier. Cannot rule out a few thunderstorms at this time. Sunday looks to dry out a bit as the upper ridge axis crosses over the CWA and suppresses rain chances. However, height rises does make Sunday the warmest day with low 90s popping up in most places east of the mtns. Meanwhile, an upper low forms over the southern plains and lifts NE, bringing a chance for a FROPA across the mountains Monday, increasing rain and TS chances once again. At this time, guidance has decent upper flow of 30-40kts and sufficient instability. Modeled soundings show steep sfc-3km lapse rates, but with a strong T/Td spread and inverted-V. Will continue to monitor, though it appears to be more typical TS with a frontal passage. Overall, hotter temps returning for most of the holiday weekend and TS chances each day. && .LONG TERM /TUESDAY THROUGH THURSDAY/... As of 220 AM Friday: Continuing with Monday night onward, the pattern becomes generally more dry as far as the synoptic pattern goes. Any remaining FROPA should be weakened closer to Monday night and pinch off rain and thunderstorms chances by Tuesday. As the strong upper low lifts towards the Great Lakes, a strong ridge builds over the central CONUS, taking on an omega pattern toward the north. Meanwhile, high pressure amplifies zonally to the south and balances height rise/falls through at least Wednesday. Long range models show an upper trough dipping southward from the Great Lakes. Given how far out the model runs are, there is still much uncertainty as to how far south and if the trough reaches the CWA. GFS suggests a stronger pressure gradient and possible rain chances, while the EURO remains less enthusiastic and keeps the area dry. After Wednesday, the ridge axis from the central CONUS propagates eastward toward the CWA and shunts rain chances with strong subsidence aloft. Temperatures should remain close to climo through the period as well. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... At KCLT and elsewhere: A low confidence forecast this morning because of much uncertainty with the timing, coverage, and location of convection over the next 24 hours. Most of the convection will probably be organized around outflow boundaries and waves aloft, reference the two area of showers and storms working their way eastbound early this morning. We will handle this with amends and TEMPO groups as appropriate, to handle the restrictions around the precip. It is possible the precip will lead to patches of MVFR to IFR ceiling/vis with stratus and fog through daybreak, but it should mix out quickly. Wind will be variable and light. For Friday, will go VFR prevailing, with a PROB30 for afternoon thunderstorms and associated restrictions. Wind should be W to NW. After the loss of daytime heating, we should have only debris cloudiness. Outlook: A unsettled pattern will linger thru the weekend and into early next week, allowing for diurnal shower and thunderstorm chances each day and fog development each night/morning. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...CP NEAR TERM...PM SHORT TERM...CP LONG TERM...CP AVIATION...PM