Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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553 FXUS62 KGSP 091531 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 1131 AM EDT Sun Jun 9 2024 .SYNOPSIS... A cold front moves in today with returning shower and thunderstorm chances, mainly this afternoon and evening. The front moves south of the area Monday and Tuesday with dry conditions expected. Forecast confidence lowers through the rest of the week as overall pattern is uncertain. For now, a chance of afternoon and evening showers and thunderstorms is expected to return late in the week with above normal temperatures. && .NEAR TERM /THROUGH TONIGHT/... Key Messages... 1) Lingering Cloud Cover and Light Rain May Limit Both the Severe Weather Potential and High Temperatures this Afternoon 2) Another Round of Rain is Expected to Develop Overnight As of 1125 AM EDT Sunday: Cloud cover across the forecast area has allow temps to stay much cooler than forecast so far so lowered temps a few degrees through the morning hours to factor in the limited insolation. No other changes were needed this update. Otherwise, light rain continues tracking eastward across the central portion of the CWA this morning but it continues to gradually fall apart the farther east it goes. Large scale height falls will carve out a broad trough across the East by end of the period, with a series of embedded MCVs expected to ripple across our region, esp this afternoon and evening. A cold front is forecast to move into the forecast area this afternoon, and move steadily east throughout the afternoon/evening. This will provide the primary focus for initiation of deep convection. Uncertainty persists regarding the magnitude of destabilization this afternoon, owing primarily to uncertainty re: the extent, longevity, and thickness of this morning`s debris cloud cover and attendant impacts on insolation. Our best guess based upon a consensus of deterministic and probabilistic guidance is that sbCAPE will peak at around 1500 J/kg across much of the area this afternoon. With deep layer shear expected to range from 30-40 kts, instability is expected to be just enough to yield a marginal severe storm threat. Shear values may support a couple of rotating cells, but forecast low level shear and SRH values are such that the tornado threat is minimal, and isolated damaging wind gusts and large hail will be the main threats. Max temps are forecast to be about a category above normal, with temps likely reaching or exceeding the 90 degree mark across the southeast quadrant of the CWA. However, cloud cover from this morning may limit highs somewhat this afternoon. Convective chances linger into the overnight hours, especially across the southern half of the CWA, as the front takes its time clearing the area of moisture. However, overnight convection is expected to be tame...likely more showery than anything...as instability quickly weakens owing to very poor mid-level lapse rates. Min temps are expected to be close to normal. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 145 AM EDT Sunday: The aforementioned cold front will be in the vicinity of the southern portion of the CFWA and may keep a few lingering showers across the Upstate and northeast Georgia through mid-morning Monday. Otherwise, drier air filters in by Monday afternoon thanks to a continental surface high building in from the northwest and the front continuing to push southward. Cyclonic flow aloft will remain in place as the area of high pressure sets up shop across the southern/central Appalachians by the end of the forecast period. A shortwave will carve out of the base of the cyclonic flow and shift the axis offshore by 12Z Wednesday. Either way, the sensible weather will remain dry after Monday morning with temperatures at or slightly below normal for max/min through the short term. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 300 AM EDT Sunday: Run to run consistency is still out of whack amongst the guidance, especially for the second half of the medium range. One thing that seems evident is the airmass will moderate, with hot and muggy conditions returning by the extended forecast period. Model guidance continue to develop a surface low over the eastern Gulf, but becomes nearly stationary due to very weak steering flow. The GFS and ECMWF keeps the CFWA dry for a good portion of next week, with some resemblance of a rex blocking pattern developing. Going to stick with the NBM due to the low confidence in the forecast, but will need to monitor the position of this low as a heavy rainfall threat will occur if it lifts north into the region at any point due to the plume of deep tropical moisture associated with this system. Temperatures will be slightly above normal for much of the period. && .AVIATION /16Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: VFR conditions are forecast to prevail through the period. Mid and high level clouds will remain across much of the Terminal Forecast Area...especially western areas this morning as a weakening complex of showers and storms moves across the region. This feature is not expected to produce any convection or restrictions at the terminals this morning, although KAVL may see -RA for a short period this morning. However, increasing moisture and instability ahead of an approaching cold front is expected to support scattered shower/thunderstorm development across the area during the afternoon. Prob30s for TSRA are warranted at most sites, primarily from late afternoon into the evening hours. Shower chances will linger well into the overnight, esp across the southern half of the area, as the cold front takes its time pushing through. Winds will favor light SW or light/vrbl this morning, increasing to SW at around 10 kts late morning into the afternoon, with some gusts in the 15-20 kts range possible. Directions will turn toward the W/NW during the late afternoon and evening as the cold front pushes through the area, with light winds turning steadily toward the N overnight. Outlook: Drying sfc high pressure is expected to gradually spread over the area on Monday and linger through the first half of the week. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...CAC NEAR TERM...AR/JDL SHORT TERM...CAC LONG TERM...CAC AVIATION...JDL