... Cold and dry high pressure will remain over the Mid-Atlantic region tonight and then move offshore on Sunday. Temperatures rebound to above average next week, as another area of high pressure spreads over the region and lingers into midweek. A moist cold front will move through the forecast area from the west on Thursday, bringing increased chances for rain.
NEAR TERM /THROUGH SUNDAY/... As of 930 PM: No major changes this update. High pressure is becoming centered off the East Coast though still extends inland over the CWA. Cirrus have already spread over most of the area and will make for a generally cloudy night. Light southerly wind continues, where not having calmed nocturnally. Temps appear on track with cirrus having a moderate effect to limit radiation, but made minor touch-ups thru early Sun morning. Lows still are expected to be near normal.
An approaching weak short wave will cause a weak low to form in the inverted trough along the Carolina coast. There will be an increase in low level moisture, however it is much deeper to our east. Isentropic lift shows shows a similar distribution. Precip chances will be much better to our east as a result, but light rain will be possible south of I-85 in the eastern Upstate and east of CLT. With increasing support for the idea the precip will really focus to our east, PoPs have been kept no better than slight-chance around midday, mainly east of I-77. Values remain below slight-chance even in Charlotte and Rock Hill. Low cloud chances will be better in that part of the CWA as well with some low clouds still possible across parts of NE GA and the Upstate. Clouds should begin to clear late in the day. Light SW winds are expected. Highs will be near normal most locations, but slightly below over the I-77 corridor given the likelihood of lower clouds.
SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 235 PM EST Saturday: The short-term fcst picks up at 00z on Monday with a broad upper trof amplifying over the Ohio River Valley and its associated trof axis moving over our area early Monday. The trof will translate off the Atlantic Coast Monday night with heights rebounding in its wake and upper ridging building to our south and persisting for the remainder of the period. At the sfc, warming SLY return flow will set up over the CWA on Sunday and help to modify the airmass. Late Sunday into early Monday, a weak cold front will move thru our area from the NW. This boundary still appears mostly dry with the better dynamics remaining to our north. In its wake, broad high pressure will spread back over our region and linger for the rest of the period. Temperatures will remain 1 to 2 categories above climatology thru the period.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 215 PM EST Saturday: The extended fcst picks up at 00z on Wednesday with upper ridging centered to our south over the Bahamas, while a northern-stream upper trof moves east of the Great Lakes. At the same time, southern-stream upper trofing will be translating over the far SW CONUS and may form an h5 closed low as the period begins. By early Thursday, this trof/ low will lift up and over the upper ridge and towards the Great Lakes, while the backside of the trof amplifies again over the Central CONUS. Over the next couple of days, this trof will translate eastward and push the upper ridge offshore. The trof axis is expected to be moving over our area by the end of the period next Saturday. At the sfc, very broad high pressure will be sliding off the Atlantic Coast with warming, SLY low-level flow established over the region as the period begins. At the same time, a weak cold front will stall out to our north as its parent low quickly pulls away from it over eastern Canada. As Wednesday progresses, another sfc low will spin up over the ArkLaTex region and lift NE towards the Great Lakes. This will bring a moist cold front to our doorstep by early Thursday. The front is expected to move thru our CWA fairly quickly, but then stall out over the coast as another vigorous low develops to our SW and pushes a moist warm front over the Carolinas on Friday. Most of the extended guidance has the center of the low lifting up and over the Carolinas late Fri/early Sat with drying high pressure behind it. As for the sensible fcst, Wednesday still looks mostly dry with PoPs ramping up Wednesday night and peaking just below likely for the Thursday fropa. I kept slight to solid chance PoPs for the rest of the fcst period due to the remaining uncertainty wrt the track/timing of the next low pressure system. At this time, convective and/or flooding potential through the period appears minimal at best, even over our southernmost zones. Temperatures start out well-above normal on Wednesday and remain there thru Friday. By the weekend, they are expected to cool to near-normal, if not a few degrees below.