716 FXUS62 KGSP 170527 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 127 AM EDT Thu Apr 17 2025 .SYNOPSIS... Dry high pressure lingers over the area through the weekend and temperatures warm a little each day. A cold front will approach from the west early next week, and could bring some showers and a thunderstorm or two to the area on Monday and Tuesday. && .NEAR TERM /THROUGH TODAY/... As of 940 PM... Key Messages: 1) Clear conditions tonight may result in patchy frost in a few mountain valleys and in a few spots along/north of I-40 in NC. 2) Mostly sunny Thursday and still dry. Less potential for fire danger. High pressure now centered over the central Great Lakes will build SE`wd this evening and center over the CWA by morning. Winds have generally become much lighter since late afternoon with decoupling evident in some spots, although portions of the I-85 corridor maintain a light SW wind and higher dewpoints where the high has not yet had an impact. Not expecting the high to build in like a cold front and induce a sharp decline in either of those elements, although calming/drying should arrive by midnight or a little later. Already seeing temps fall off more rapidly, however, in those spots that have already decoupled. Overall, though, the min temps forecast by the day shift appear on track, a few degrees below NBM in the outlying areas. Lows will still fall into the mid to lower 40s across the low terrain, and winds will gradually veer around to the northeast before daybreak. Upper 30s are possible in isolated or typically colder spots in the Piedmont/Foothills north of I-40, with mid to upper 30s in mountain valleys. Despite relatively low dewpoints, the decoupled PBL eventually exhibits dewpoint depressions small enough that where temps fall into the mid 30s, some frost now appears possible. Think it is too patchy to warrant an Advisory, but a mention has been added to the forecast grids. Another sunny day is expected tomorrow, with winds out of the southeast and temps around a category warmer than today`s. A steady increase in low-level moisture owing to strengthening SE flow off the Atlantic will result in dewpoints not quite as low as today`s, so fire weather should be somewhat less of an issue. Cloud cover will begin to increase late in the period with a weak vort blob seen on model progs and moisture AOA about 700 mb. With low levels remaining dry and only weak forcing, this is not enough to warrant a mentionable PoP except for a couple of spots in the northern mountains. Some virga could be seen elsewhere. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... As of 2:15 PM EDT Wednesday: Broad southerly return flow will become established over the area as high pressure moves off the Southeast/Mid-Atlantic coast late in the week. After the 850 mb ridge axis passes through, a warm front will quickly lift northward through the area Thursday night. Weak isentropic lift across the boundary and additional forcing from a mid-level shortwave trough could be accompanied by an increase in cloud cover at night, but the system is generally moisture starved, so the forecast remains dry with PoPs below 20 percent. The warm front will move well to our north on Friday, resulting in a significant warming trend with temperatures about 10 degrees above normal (highs in the 70s in the mountains, lower 80s elsewhere) Friday and 10-15 degrees above normal Saturday. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 2:15 PM EDT Wednesday: Surface high pressure will remain anchored to our north over the Northeast US and to our east the Southeast U.S. coast through early next week. Meanwhile, a southern- stream shortwave trough and attendent surface low is expected to lift northeastward from the Great Plains to the Great Lakes. A trailing cold front will approach from the MS Valley. Tend to favor a slower solution with arrival of the front as amplified S-SW flow across the eastern seaboard becomes oriented more parallel to the boundary, causing its eastward progression to slow. The most likely timing of the front is Monday afternoon or night, but it could be as early as Monday morning. If the downstream ridge block does not break down as quickly as the model consensus currently depicts it, there is a potential for this front to stall just to our east near the coast. This would prolong the chances for rain showers into Tuesday. The NBM shows an increasingly large spread in temperatures Monday night and Tuesday owing to the uncertainty in the pattern. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... At KCLT and elsewhere: VFR through the period. NNW winds to start the period will diminish, briefly lgt/vrb before veering around E to SE by later this morning (current timing is 16z at KCLT). Direction will continue on around the dial toward S (except for KAVL remaining SE down-valley), though more lgt/vrb again with high pressure in control overnight. Wind speeds at best 5-10kt this afternoon with mixing. High to mid-level cloudiness will increase this afternoon and evening especially across NC sites but no restrictions expected. Outlook: Dry/VFR conditions will continue into the weekend. The next chance of rain and associated restrictions won`t be until early next week. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...DEO/MPR NEAR TERM...MPR/Wimberley SHORT TERM...JPT LONG TERM...JPT AVIATION...TDP