Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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610 FXUS62 KGSP 051850 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 250 PM EDT Fri Jul 5 2024 .SYNOPSIS... Above normal temperatures will persist through the weekend. Meanwhile, a cold front moves in from the north and becomes stationary near the southern portion of the forecast area on Saturday. This front will increase the chance for thunderstorm activity outside the mountains through Sunday. More typical summertime thunderstorm development returns Monday and persists through next week. && .NEAR TERM /THROUGH SATURDAY/... As of 230 PM Friday: Thunderstorms will remain numerous across the mountains through late afternoon with scattered activity developing into the Piedmont through mid-evening within the axis of 2500-3500 j/kg SBCAPE values. Decent enough storm motion should limit the excessive rain threat, but we will continue to monitor for any training storms, especially in the high terrain. Thanks to an axis of moderately high downdraft CAPE values analyzed across the piedmont, there remains the potential for a few storms to produce damaging wind gusts. Otherwise, after storms ash out, temperatures will remain warm all night with daybreak minimums flirting with record high minimums. More summertime storms are expected on Saturday as baroclinic zone activates, aided by vort energy translating into the region within the moderate sw flow aloft. The short range model consensus actually has the better forcing east of the Blue Ridge tomorrow, where cvrg should blossom to numerous. Just like today, there is the ongoing threat for isolated excessive rainfall and damaging wind gusts. The llvl thickness ridge shifts east away from the region on Saturday displacing heat advisory concerns to the I-95 corridor and coastward. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 200 pm Friday: A broad long wave trough will be centered across the central Conus through the short term, with the southern Appalachians and vicinity expected to be near the southern periphery of the subtropical jet. A surface boundary...perhaps being displaced by a lee/thermal trough with time, will remain over or near our CWA through the period, which in light of continued very moist conditions (PWATs at least the 75th percentile in terms of climatology through the period) will continue to enhance diurnal convective chances early in the new week. Above-normal coverage of convection is expected both Sunday and Monday afternoon/evening, with general likely PoPs forecast over the mountains, and 50-60% chances across the Piedmont both days. Instability will be adequate for multiple strong+ storms, with a few pulse-y or multicell cluster severe storms possible. Unusually high moisture, along with cell motion of < 10 kts, and some potential for training storms will yield a threat for locally excessive rainfall both days, especially for locations that see multiple days of heavy rainfall. With the increased activity and expected relatively early start to convective initiation...as well as lower heights aloft, temps will be cooler than they`ve recently been...generally around or even slightly below climo. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 225 pm Friday: The early portion of the medium range will be a battle for influence on the weather across the southern Appalachians between an upper trough across the central Conus, and a subtropical ridge over the western Atlantic. The consensus of the latest global model guidance suggests the ridge may begin to win the day toward mid-week. Thus, PoPs for diurnal convection will trend down closer to climatology Tue/Wed. A few strong-to-severe storms producing microbursts and locally heavy rainfall will remain possible, although with a diminishing threat due to fewer targets of opportunity. (There will almost certainly be pockets of the CWA with relatively poor antecedent conditions, so the excessive rainfall threat will remain elevated for those areas.) Moisture associated with the remnants of T.C. Beryl pose a potential fly in the forecast ointment late in the period. However, the GFS and Canadian tend to spin the cyclone down over Texas, while even the ECMWF...which has consistently maintained a closed circulation into the Tenn Valley in the Day 5/6 time frame...keeps the notable impacts very close to the center. So...even indirect/minimal impacts appear unlikely for our area at this time. Temperatures are forecast to remain within a degree or two of climo through the period. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... At KCLT...Will plan on holding off on chances for TSRA until closer to 00z based on convection allowing model timing of clusters of deep convection moving off the higher terrain after mid-afternoon and approaching the terminal during the early evening. After storms dissipate by midnight and within the moist blyr layer, there remains model signals of a period of lower clouds, perhaps an mvfr cig around daybreak. Unless rain actually materializes, will also hold off on introducing any vsby restrictions. An activating frontal zone is fcst for the Carolina piedmont Saturday afternoon, so introduced tsra chances after 18z. Outlook: Diurnally-driven convection will continue each day thru the weekend and into early next week, leading to sct showers and thunderstorms and possible restrictions each afternoon/evening. Fog and/or low stratus may develop each morning, especially over areas that received rain the previous day. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...Heat Advisory until 8 PM EDT this evening for GAZ018-026-028- 029. NC...Heat Advisory until 8 PM EDT this evening for NCZ036-037-056- 057-068>072-082-508-510. SC...Heat Advisory until 8 PM EDT this evening for SCZ008>014-019- 104>109. && $$ SYNOPSIS...SBK NEAR TERM...CSH SHORT TERM...JDL LONG TERM...JDL AVIATION...ARK/CSH