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Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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834 FXUS62 KGSP 031353 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 953 AM EDT Wed Jul 3 2024 .SYNOPSIS... Hot and humid conditions will become established once again for the second half of the week. Afternoon showers and thunderstorms will be possible each afternoon starting Thursday, especially over the mountains. A cold front may enhance thunder chances on Saturday. && .NEAR TERM /THROUGH TONIGHT/... As of 935 AM: Temps appear on track for today but based on obs so far this morning, dewpoints may have been a hair too low, so adjusted them upward through early aftn when mixing is still expected to have some effect. Touched up sky cover also, to reflect latest extent of low clouds scattered across the Piedmont. Cloud streets are forming which suggests cloud cover will last longer than originally expected, but still think skies will trend clearer with the aforementioned mixing. The upper pattern should slowly evolve over the next 24 hours, with the axis of a mid/upper ridge over the Appalachians to start the day getting tilted over positively and pushed to the East Coast by a nrn stream short wave that trails off across the OH Valley region. Altho the sfc high centered over New England this morning gets steadily pushed offshore as a result, it should still be able to ridge back and control our weather thru tonight. The movement of the sfc high should allow for some moisture to trickle back in from the Atlantic this afternoon, thus beginning our return to more typical humidity. Won`t rule out a few ridgetop showers during peak heating if the moisture makes it far enough west. High temps will creep back up above normal this afternoon and mild low temps can be expected as well. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 218 AM EDT Wednesday: The western Carolinas should be ensconced in a SW flow regime by Thursday, although at the low-levels the positioning of an axis of high pressure over the western Atlantic will result in trajectories mostly off the Atlantic coast, not the Gulf of Mexico as is typical of SW flow patterns. That might serve to hold our dewpoints in the lower 70s, although with afternoon temps in the mid 90s in the upper 90s to low 100s outside the mountains. Some afternoon showers and thunderstorms will be possible, with 1000-1500 J/kg sbCAPE expected across the area...but still think triggering will only occur over the NC mountains. On Friday, temps will get even higher, and much of the area will see afternoon heat index values above 100 degrees. In keeping with the past few forecasts...trended toward raw model output for dewpoints...which keeps most of the forecast area clear of any heat advisory criteria for Friday afternoon. Will monitor going forward. Once again, diurnally-driven showers and thunderstorms will be likely on Friday, and with the approach of a frontal boundary from the Ohio Valley and better instability (1500+ J/kg virtually everywhere) it`s possible we could see some cells pop up outside the mountains. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 227 AM EDT Wednesday: Long-range guidance has doubled down on the idea of a cold front arriving Saturday, and now points to a somewhat faster and more aggressive push into the forecast area. This`ll enhance coverage of showers and thunderstorms on Saturday, amid what should be a very moist and unstable environment. There`s less agreement on how the second half of the weekend will evolve...with some ensemble solutions pushing the deteriorating front all the way through the area, and others allowing it to stall and even surge back north as a sfc wave works its way up from the Deep South. Seems likely that some kind of unsettled weather will be possible through the end of the forecast period, as even the drier solutions have a return to S/SE flow driven by the Bermuda high by the start of the new workweek...meaning hot, humid weather and diurnal showers and thunderstorms. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... At KCLT and elsewhere: The patchy stratus/stratocu which developed around daybreak have thinned, although in the same areas low cumulus are forming, which will prolong the duration of SCT-BKN clouds below 030 perhaps until 15-16z. Outside of northeast GA these clouds should then mix out or scatter and lift to VFR level. Thereafter, confidence still highest for VFR at all sites, with only sct low clouds. Wind will be light SE to S and SW through the daytime. Any remaining low clouds should dissipate with sunset. Wind will probably go light/variable again. Outlook: A return of more typical mid-summer humidity and diurnal convection returns Thursday into the weekend leading to possible restrictions each afternoon/early evening. Fog and/or low stratus may develop each morning, especially for areas that received rain the previous day. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...MPR NEAR TERM...PM/Wimberley SHORT TERM...MPR LONG TERM...MPR AVIATION...PM/Wimberley