... Cold Canadian high pressure will bring below normal temperatures through the middle of the week. Temperatures gradually return to near normal late in the week. The next cold front crosses the area Friday night. Seasonal high pressure slowly builds in by Monday.
NEAR TERM /THROUGH WEDNESDAY/... As of 633 PM Tuesday: All is well across the western Carolinas and northeast Georgia, courtesy of high pressure to our north. Expect a cold night given the good radiational cooling conditions. No changes.
Otherwise, southern stream upper troffing will eventually move off the SE Coast later tonight and tomorrow as upper ridging spreads back over the area from the west. At the sfc, strong and cold high pressure will cross the Ohio Valley, and maintain cold thicknesses over the region into Wednesday. By the end of the near-term period late Wednesday, the high is expected to be centered over southern New England with sfc winds still out of the NE. The period will remain dry with mostly clear skies into tomorrow afternoon. Sct high clouds will begin to spread back over the CWFA from the west later tomorrow afternoon. Under mostly clear skies, lows overnight will bottom out well below climo again with teens over most of the higher terrain and low 20s elsewhere. With increasing thicknesses tomorrow, highs will rebound to near normal across the higher terrain, but remain about a category below normal outside the mountains.
SHORT TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... As of 200 pm Tuesday: A short wave ridge will progress off the East Coast early in the period while large scale height falls will be overspreading the central Conus in response to multiple speed maxima diving along the east side of a deep western ridge. This will culminate in the development of an upper low over the central Great Plains/Mid-Mississippi Valley by 00Z Friday. Associated frontal zone and WAA regime will develop across the Southeast Thu night into Friday, bringing the next good chance for precipitation to the forecast area by Fri morning. Moisture and forcing are expected to encounter a seasonably cool/dry air mass across the western Carolinas and northeast GA early Friday, such that p-type will be a concern at least initially across the mtns. While the cool/dry air mass indicates likely development of in-situ cold air damming on Friday (temps a solid 10 degrees below climo in most areas), the upper air pattern and location of parent surface high pressure are forecast to be unfavorable for cold air maintenance. As such, forecast profiles support possible snow across the higher elevations at precip onset, followed by a brief transition to a mix before warm advection would force a changeover to rain, suggesting potential for only light accums, mainly above 3500 feet or so.
Otherwise, just a chilly rain Friday, with pops peaking at 80-90% during the afternoon before tapering off quickly during the evening. Cooler air spilling in behind the system Fri night into Saturday on the heels of developing W/NW flow will support snow shower chances across the high elevations along the TN border through the end of the period. Current global model guidance depicts rather backed and weak low level flow throughout that time, so ingredients appear to be lacking for significant accumulating snow showers at this time. Temps will end the short term period a little below normal.
LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... As of 115 PM Tuesday: Above average model agreement provides above normal confidence in the extended portion of the forecast, which is expected to be fairly quiet. Broad troughing aloft will likely remain over the area Sunday before a short-wave "kicker" drops into the region and effectively pushes the rough offshore. Flat ridging will likely build into the region in its wake around Tuesday of next week. Cold advection associated with northwest flow a low levels will likely persist into Monday before waning into Tuesday. It appears the flow may be favorable to deliver moisture from the Great Lakes into the region through Monday, providing the potential for clouds and northwest flow snow showers at times focused across the mountains near the Tennessee border. Downsloping flow east of the mountains will provide generally fair skies and moderate the airmass somewhat, especially during the daytime hours. Slightly below normal temperatures will moderate to near normal sometime early next week in response to the flat ridge building into the area.