Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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915 FXUS62 KGSP 130533 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 133 AM EDT Mon May 13 2024 .SYNOPSIS... As low pressures approach from the west, moisture increases to start the week and rain returns to our area Monday afternoon and evening. Rain and thunder are expected on Tuesday and Wednesday, followed by a brief period of dry conditions on Thursday. Another low pressure arrives for next weekend bringing more rain. && .NEAR TERM /THROUGH TODAY/... As of 130 AM: Thickening cirrus spreading in from the west may be slowly the nocturnal temp trend a bit, so have blended in CONSshort with latest obs to bring temps up. Given the expected cloud cover, bumped min temps up a deg or two. But overall, no major changes with this update. Otherwise...ridge axis now situated over the lower MS Valley with attendant sfc high extending over the Cumberland Plateau. These features will build east tonight, and sfc winds will come around to the NE across the Piedmont. Sfc/upper low in the Plains will activate a warm front to our southwest overnight, but it looks pretty unlikely any of that precip will develop into our area in the morning. PoP onset has been delayed compared to previous fcsts, with dry air to overcome and the lift being relatively weak. Midlevel clouds however will increase in numbers overnight, but slow enough that decent radiational cooling still should occur, so still went with bias-corrected guidance blend similar to what has worked well in recent nights. Of particular note, the pattern still may permit eventual development of in-situ CAD but see no need to expect that will begin tonight, without precip. Warm front will shift northward over the sfc high in the morning, possibly resulting in light precip developing near the Blue Ridge Escarpment and in NE GA by noon. Abundant alto/cirrus cloud cover will be in place but low clouds are appreciably slower to develop. Guidance mostly holds off with QPF until after 18z, with saturation occurring from the top down. Still favor precip chances no better than chance range for the majority of the CWA, the exception in the Escarpment/GA areas where saturation appears to occur earliest; those areas will see likely PoP mention by late afternoon. Thus, formation of CAD probably will not be until after peak heating, but the cloud cover will impact highs especially SW of I-26 where they should be in place more or less all day. Lack of CAD also suggested by model consensus for winds going southerly across the CWA by late morning. We end up with highs several degrees below climo in the SW, but near or slightly above normal in the sunnier NE. Any convection afforded by the upglide likely will be too shallow to result in thunder. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY/... As of 100 PM EDT Sunday: We remain on track for the likihood of dreary sensible wx conds Monday night as a period of moist llvl upglide flow expands atop of wedge-like pattern. Widespread low overcast, rain, drizzle and fog is on tap. Energy rounding the base of potent Ohio Valley upper low will eject NE into the region on Tuesday. Along with an associated slug of deeper moisture, showers are expected to be widespread. It remains probable that the wedge front, present along the SE fringes of the cwfa to start off the day, will be able to erode, probably uncovering a small amount of positive SBCAPE values SE of I-85 Tuesday afternoon. Within the robust deep shear there remains the possibility of svr tstm development along and SE of retreating/dissipating wedge front into Tuesday evening. The cwfa is progged to be within a cleaner warm sector environment on Wednesday, all beneath cyclonically curved flow aloft thanks to the lingering, but departing upper low axis. As temperatures warm to seasonable mid-May levels, the atmosphere will becoming moderately unstable. Coverage of diurnally enhanced tstms should becoming numerous, especially in Western NC where the flow and forcing will be greater. There should exist enough shear to promote a few severe storms. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 200 PM EDT Sunday: Save for the small chance for isolated ridgetop forced showers, we are expecting an essentially suppressed atmosphere on Thursday as upper ridge axis translates atop the SE CONUS. Lower elevations will warm into the lower 80s. The next slug of southern stream deeper moisture and energy remains progged to quickly advect into the cwfa on Friday. The latest medium range guidance is in decent enough agree with respect to the mass fields on Friday with considerable convective response, so the inherited sensible wx featuring numerous diurnally enhanced thunderstorms will remain as is. Less than usual confidence exists regarding the specifics for next weekend but with the wavy pattern likely to linger along with spokes of southern stream energy rippling eastward, above climo pops will be featured each day. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... At KCLT and elsewhere: Cirrus will continue to steadily thicken with altocu moving in during the morning and low VFR stratocu cigs by afternoon. Light and variable to light NE wind early this morning becomes SE by late morning then S for the afternoon. Low level moisture and isentropic lift move in through the day with cigs falling to MVFR during the afternoon then IFR during the evening. Precip chances will increase through the afternoon into the evening as well. Weak elevated instability is possible during the evening but chance of TSRA too low for the TAF at this time. Wind turns S to SE during the evening. Outlook: Scattered thunderstorms develop Tue and Wed afternoons bringing a chance for periodic restrictions. Some nocturnal restrictions remain possible Tue and Wed nights. Brief drying expected Thursday. Convection and associated restrictions return ahead of a cold front on Friday. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...DEO NEAR TERM...ARK/RWH/Wimberley SHORT TERM...CSH LONG TERM...CSH AVIATION...RWH