Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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757 FXUS62 KGSP 092139 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 539 PM EDT Sun Jun 9 2024 .SYNOPSIS... A cold front moves south of our area becoming stationary through mid week with dry conditions under weak high pressure for Monday through Thursday. Isolated to widely scattered showers and thunderstorms are expected by next weekend as a weak cold front approaches from the north. Temperatures are expected to be well above normal at end of the week. && .NEAR TERM /THROUGH MONDAY/... Key Messages... 1) Strong to severe storms possible this evening. 2) Another round of sct to numerous showers is likely overnight and into early Monday morning, largely confined to the I-85 Corridor and south of it. 3) Dry conditions return Monday afternoon. As of 5:25 PM EDT Sunday: A fairly robust cluster of showers with some embedded thunderstorms associated with a weak cold front is currently approaching the NC/TN border. The latest CAM guidance has this activity moving into the NC mtns over the next couple of hrs and continuing its SE trajectory and eventually moving SE of our CWA later tonight. 1000 to 1500 J/kg of Sfc-based CAPE has already developed across much of our area and 30 to 40 kts of deep-layer shear is also in place. This should allow isolated strong to severe thunderstorms to develop as this activity moves thru our area this evening. The SPC Day 1 Severe Wx Outlook has the majority of our fcst area in a Marginal Risk and this still seems reasonable. The main hazards with any severe storms that develop are damaging wind gusts and large hail. The most likely window for severe wx appears to be slightly later, ie, from roughly 6pm to 10pm EDT. Otherwise, a brief drying period is expected once the cold front pushes south and east of the fcst area later this evening. Upper shortwaves will track overhead the forecast area overnight into early Monday morning allowing for widespread cloud cover and rain showers to develop. Instability will be lacking so maintained no mention of thunder overnight. Lows tonight will end up a few degrees above climatology thanks to both cloud cover and precip limiting radiational cooling. Timing of the second wave of convection will be from roughly 3am-9am. However, some isolated activity may linger across the southern zones throughout the morning hours. Dry high pressure will gradually build in from the west throughout Monday allowing dry conditions to return by Monday afternoon. Temperatures will be cooler on Monday, around 2-4 degrees below climo, with highs only reaching the low 80s east of the mtns. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... As of 205 PM EDT Sunday: Short waves drop across the area through an upper trough on Tuesday. The trough moves east Wednesday with weakening NW flow over our area. The cold front from the near term slowly moves south away from the area Tuesday with dry high pressure building in on Wednesday. Can`t rule out an isolated shower Monday evening with lingering low level moisture and weak forcing, but chance too low to include in the forecast for now. It will be breezy Monday night and Tuesday though. Dry conditions and light winds expected Wednesday. Below normal lows Monday night rise to near normal Tuesday night. Near normal highs Tuesday rise a couple of degrees above normal Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 220 PM EDT Sunday: Still some run to run consistency issues with the guidance. That said, there does seem to be a trend toward a drier forecast. A series of weak short waves move through the flow, mainly north of our area through Friday. Then a semblance of a Rex Block develops Saturday into Sunday with an upper anti-cyclone sliding into the Southeast by Sunday, and a weak upper low moving east across the Gulf of Mexico. The result is weak and generally dry high pressure Wednesday and Thursday with the potential for diurnal convection Saturday as a weak cold front crosses the area. Diurnal convection possible again Sunday as a moist southerly flow develops. A warming trend takes place with highs nearly 10 degrees above normal by Saturday, which drop back a few degrees for Sunday. Lows rise to around 10 degrees above normal. && .AVIATION /22Z SUNDAY THROUGH FRIDAY/... Key Messages... 1) Thunderstorms Expected this Afternoon Ahead of a Cold Front 2) Widespread Rain expected Overnight into early Monday Morning 3) Cigs and Vsbys should generally range from MVFR to VFR through the period At KCLT and elsewhere: Light rain continues pushing east this afternoon, with only isolated activity lingering along/near I-77. Low-end gusts are noted at KAVL and KAND as of 18Z and KGSP and KGMU could see gusts develop this afternoon as well. Gusts should diminish by the early evening hours. Cloud cover is starting to clear across portions of the terminals this afternoon which should allow the atmosphere to become unstable. However, cloud cover will gradually increase from west to east again, becoming BKN to OVC, later this afternoon ahead of a cold front. The cold front will lead to -SHRA/-TSRA late this afternoon into early this evening as it tracks overhead. Have TEMPOs at all terminals, with the exception of KAND which is expected to remain dry, to account for the convective potential. Cigs should generally remain VFR outside of TSRA. Wind direction remains W`ly east of the mtns this afternoon. Winds will remain NW at KAVL through the TAF period, while winds east of the mtns will turn N/NW behind the front this evening into tonight. Brief drying is expected before a round of widespread showers tracks across the terminals overnight into early Monday morning. Handled this potential with PROB30s across all terminals. -SHRA should start between 07Z and 09Z and push out between ~11Z and 13Z and should allow cigs to fall to high-end MVFR levels, mainly across the SC Upstate terminals. High pressure will build into the region throughout Monday leading to much drier conditions and allowing VFR cigs to gradually return. Cloud cover will gradually decrease throughout Monday becoming FEW to SCT. Winds east of the mtns should become more variable around daybreak Monday before turning WSW/SW Monday afternoon. Outlook: Dry sfc high pressure will linger through mid-week leading to quieter weather. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...DEO NEAR TERM...AR/JPT SHORT TERM...RWH LONG TERM...RWH AVIATION...AR/JPT