Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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686 FXUS62 KGSP 120721 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 321 AM EDT Wed Jun 12 2024 .SYNOPSIS... Dry conditions will continue through the week under weak high pressure. Isolated to widely scattered showers and thunderstorms are expected early next week as a weak cold front approaches from the north. The hottest days are expected to be Friday and Saturday, then the heat should continue into next week. && .NEAR TERM /THROUGH TONIGHT/... As of 315 AM EDT Wednesday: Starting to see the low- and mid-level clouds retreat northward with some clearing over the Upstate and northeast Georgia. The one monkey wrench being thrown into the forecast is a band of cirrus moving in from the southwest. Adjusting sky cover and temperatures based on this development. The forecast still remains on track. Retreating upper trough over the northwestern Atlantic will set the stage for rising heights and the flow aloft to somewhat flatten out. Model guidance are picking up on a weak shortwave moving across the Deep South during the period and will fetch a deck of upper-level cirrus over the area. Weak surface high pressure will continue to control the sensible weather as the high gradually shifts offshore the Mid-Atlantic and Carolina Coast through the period. Expect winds to steadily come out of the east to southeast during the daytime period, providing a light Atlantic fetch across the area. In this case, shallow moisture will settle at the top of the boundary layer and underneath a mid-level subsidence inversion. Expect more cloud cover than Tuesday as a result during peak heating, but mentionable PoPs will remain out of the forecast due to the warmer air aloft helping to suppress the atmosphere and no real trigger for precip. Dewpoints will increase today to go along with a rise in temperatures as our summertime pattern begins to really settle in across the CFWA starting today. Expect afternoon highs to rise around a category or so compared to Tuesday with most locations reaching at or slightly above normal. Lingering cloud cover overnight will keep what would be otherwise a very good environment for radiational cooling. Overnight lows will be near normal as a result. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 250 am EDT Wednesday: Upper flow will become increasingly anticyclonic during the short term, as high pressure gradually builds toward the Southeast from the Southern Plains. The result will be a continued warming trend, with rather hot conditions expected by the end of the period. Meanwhile, despite steadily increasing humidity, conditions will remain unseasonably dry as the atmosphere becomes suppressed due to warming temps aloft/increasing subsidence. Some short term and convection-allowing guidance seem rather overdone with ridgetop convection Thu afternoon, as forecast soundings appear quite inhospitable to deep convection. Still...we`re getting to the point of the year in which it`s difficult to not get at least a little diurnal convection going across the high terrain...so slight chances for showers are carried there during the afternoon/early evening. Much of the same can be said of Friday...although a short wave trough passing north of the region is expected to send a weak frontal boundary through our area during the afternoon. Nevertheless, forecast soundings appear no less hostile to convective development than they do on Thursday, so PoPs are once again limited to late day ridgetop slight chances. Temperatures will be above normal through the period, with Friday expected to the hottest day of the year so far...with mid 90s expected across portions of the Piedmont. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 300 am EDT Wednesday: Upper heights will continue to rise during the early part of the extended, as anticyclone becomes centered over the Southeast during the weekend, before likely lifting into the Mid-Atlantic early in the new work week. As a result, the atmosphere will remain quite suppressed for vertical motion on Saturday, with sparse-at-most mountain diurnal convection expected. As the anticyclone begins to drift away from the area early next week, conditions will steadily become more favorable for (mainly) mountain convection Sunday through Tuesday afternoon/ evening. In fact, some global models lift a short wave trough north through the TN Valley and southern Appalachians by the end of Monday, which could further increase the convective potential for far western areas. In general, forecast PoPs trend toward climatology early next week...20-30 PoPs mainly across the western half of the area...with a small increase over these values Monday afternoon. After another day with max temps 5+ degrees above normal, conditions will moderate a bit thanks to falling heights, although max temps are still forecast to be a couple of degrees above climo through the end of the period. Increasing humidity will result in above-normal mins. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... At KCLT and elsewhere: VFR conditions will prevail through the forecast period. Ongoing stratocu will hold steady over the next few hours before scouring out around daybreak or shortly after, which is reflected in the prevailing lines at all TAF sites. Model guidance still hints at some flavor of mountain valley fog, but not expecting it to fill in at KAVL as cloud cover will hold fog development until later in the overnight period. Winds will be light and variable overnight with 060-090 cigs underneath the current cloud deck. High pressure will remain in control through the rest of the period and keep winds on the lighter side with mainly a south to southeasterly component. FEW to SCT fair weather cu will develop once again during peak heating with upper-level cirrus hovering overhead as well. Outlook: Surface high pressure remains over the area through the end of the week with minimal chance for convection and associated flight restrictions. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...DEO NEAR TERM...CP SHORT TERM...JDL LONG TERM...JDL AVIATION...CAC