... Dry high pressure will be in control of our weather for Friday into Saturday. A strong low pressure system approaching from the southwest may support a threat for heavy rain late Sunday into Monday. Northwest flow snow may develop across the mountains in its wake late Monday and continue into Tuesday.
NEAR TERM /THROUGH FRIDAY/... As of 642 pm EST: A weak surface front continues to make slow eastward progress across the region, but most of the cloudiness has temporarily pushed off to the east. Remaining instability has slowly bled away, so think our chances of any showery precip have ended, and thus the showers were removed with the early evening update. With that, our attention turns to the potential for locally dense fog across the wrn Piedmont later tonight. Some of the guidance continues to hit the fog potential hard, although the 18Z NAM showed slightly higher surface condensation pressure deficits across the I-77 corridor. Think the forecast still has the right idea, though, as when obs came back in the last hour, we notice that Lincolnton is already reporting dense fog. The cooling and drying should manage to shave some 10 degrees west to 5 degrees east off the minimum temperature forecast for Friday morning compared to Thursday morning.
A shortwave ridge will cross the southeast on Friday ahead of the next digging trough moving toward the lower Ohio Valley. Profiles will remain dry across the region, and the resulting insolation will offset the thickness cooling to keep maximum temperatures some 10+ degrees above climo in most areas.
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... As of 1245 PM Thursday...The short range period continues quiet until late in the period when PoPs pick up as llvl moisture flux increases ahead of a vigorous upper low pressure system. Before that, a weak cold front will cross the area early Sat with little upper support as an associated h5 vort lobe interacts with prevailing zonal flow. A suppressive llvl ridge will keep moist adv at bay across the srn gulf states, so have backed the going slight chance PoPs to nil with the FROPA. Strong hipres builds in Sat and will continue to transit NE thru Sun. The incoming precip will begin to form an insitu wedge with this high, however, only anticipate light rain thru the end of the period and confined mainly to NE GA and the wrn Upstate. Max temps will rise a little abv normal Sat in good insol, then arnd normal levels Sun with increasing cloud cover and precip. Mins will fall to arnd normal each night.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 140 PM Thursday...The ext range still looks active early on as a strongly supported sfc low brings high amts of moisture to the FA and a changing airmass. The op models are coming into a little better agreement with the timing and strength of the system, however, the 12Z ECMWF is still further north and agrees more with the CMC than the srn track GFS.
The guidance is now showing a distinct shift in the heavier precip axis aft 06z Mon. The first part of the overnight period will have the wrn zones under the gun for continued moderate to heavy upslope precip, then the ern FA gets decent rainfall amts. So, hydro threats are still possible across the srn BR escarpment and then the Piedmont where training cells may setup as the upper low pivots while being pulled into the mean ulvl trof/low.
The sfc low will continue advancing NE quickly aft 12z and little precip will fall aft 18z Mon, except across the wrn NC mtns where back-side NW flow -snsh will begin to develop. Soundings across the mtns show a quick change over to below freezing profiles during the afternoon, and there could be a brief wintry mix before all precip falls as snow thru the event. Still looks like elevations abv 3.5 Kft and the TN spine will take the brunt of the snowfall where adv level snow is looking probable at this point. Winds will also pick up and become gusty Mon as the sfc p/grad tightens and adv level gusts will be possible over the higher terrain. The upslope snow will begin to taper off by Tue evening as the large scale ulvl low finally pulls north of the region.
Max temps will begin the period arnd normal, then drop 10-15 degrees below normal Tue and Wed. Mins begin period abv normal, but then drop to mid to upper 20s Mon and Tue nights.