309 FXUS62 KRAH 141146 AFDRAH AREA FORECAST DISCUSSION National Weather Service Raleigh NC 646 AM EST Thu Jan 14 2021 .SYNOPSIS... Surface high pressure will temporarily move across the region today, then a strong cold front will move across the Carolinas Friday. Colder this weekend as high pressure builds into the region. && .NEAR TERM /TODAY THROUGH TONIGHT/... As of 345 AM Thursday... Water vapor satellite displayed a shortwave trough pushing east off the NC coast, weak ridging across the Midwest, and a deep trough across the Plains with it's associated low just north of ND. Surface observations showed low pressure just off the NC coast, and weak high pressure across the TN Valley. Radar displayed showers along the NC coast associated with the departing trough, and some areas of virga across central NC this morning. Low clouds across much of the region will continue to lower through early this morning, helping to drop visibility across some areas. Portions of the Triad were already observing dense fog, with visibility down to one-quarter mile. Dense fog may develop in a few other areas this morning, but currently is not expected to be widespread enough to warrant a Dense Fog Advisory. Low clouds will slowly clear throughout the morning as low pressure departs further into the Atlantic, surface high pressure builds across the Southeast and weak ridging builds aloft. Highs will mostly be in the mid-50s today, with lows in the low to mid-30s tonight. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 345 AM Thursday... The aforementioned upper low will dive south into the Midwest today, then into the Ohio Valley by Friday. The first associated trough and a surface cold front will push across central NC from west to east late Friday morning through the evening. High-res models still disagree in the exact timing the line of showers will move across the area. Precipitation looks to be mostly less than one-quarter of an inch across the region through the period, with highest amounts along the Coastal Plain. Southerly winds will increase ahead of the front, with gusts of 20-25 mph possible in the late morning and afternoon. Clouds will develop across the Triad early in the day, so highs will be the lowest there across the region. Max temps will range from the mid 40s NW to near 60 SE. The cold air will start to filter in Friday night behind the front. Conditions in the lower- layers of the atmosphere will remain above freezing through the period, so expect all precipitation to fall as rain. Skies will become mostly to partly cloudy by late Friday night as showers depart to the east from the first trough , with minimum temperatures ranging from the upper 20s NW to upper 30s SE. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 430 AM Thursday... Cooler and drier air will advect into the area on Saturday behind the cold front, with highs in the mid-to-upper-40s (slightly below normal). A second upper trough axis will swing through the area, and it should be accompanied by decent vorticity advection. The air will be dry but both the 00z GFS and 00z ECMWF, along with their ensembles, are in agreement in showing potential for some additional light precipitation, mainly in the north. Thus brought back slight chance POPs in the northern Piedmont on Saturday. Thicknesses appear low enough that a few wet snowflakes can't be entirely ruled out especially in the far NW. At the very least, increasing clouds are expected as the trough moves through. The pressure gradient between the departing low pressure and a high building in from the SW will also result in some gusty west to southwest winds, up to 15-25 mph. Skies will clear on Saturday night, but winds look to hold on a bit longer than previously thought, and the latest models are a bit warmer as a result. Thus slightly raised forecast lows on Sunday morning, to upper-20s to near 30. Weak upper ridging will briefly build over the area on Sunday, resulting in dry conditions. Temperatures should be similar to Saturday but maybe a hair warmer. Clouds will be on the increase again Sunday evening as the next upper trough approaches from the west. The system looks moisture-starved, but the 00z GFS and ECMWF did come in a hair wetter from prior runs. For now keep POPs just below slight chance on Monday morning, but this may need to be increased if trends continue. The best chance for precipitation would again be in the north. Regardless, the trough and associated cloud cover on Monday should keep highs similar to Sat-Sun. High pressure will bring a return to dry weather on Tuesday, before a southern stream wave potentially approaches on Wednesday. However, the latest GFS and ECMWF have trended slower with the system, so keep POPs at only slight on Wednesday at this time. High pressure should bring the best radiational cooling conditions on Tuesday morning, with lows in the mid-to-upper-20s, before zonal flow begins a slight modification of temperatures to near normal on Tuesday and Wednesday (highs in the upper-40s to mid-50s). && .AVIATION /12Z THURSDAY THROUGH MONDAY/... As of 630 AM Thursday... 24 Hour TAF Period: MVFR to IFR ceilings and VIS will continue across portions of the region this morning, with isolated pockets of LIFR. Low ceilings/VIS will improve by mid-morning, with VFR conditions expected into the evening. Small chance of IFR/LIFR ceilings and VIS again tonight with FG/BR. Outlook: Sub-VFR conditions, along with RA and breezy winds, will develop Friday through Saturday as a cold front moves across the region. VFR conditions will return Saturday night through Monday. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...JJT NEAR TERM...JJT SHORT TERM...JJT LONG TERM...Danco AVIATION...JJT