655 FXUS62 KRAH 181459 AFDRAH AREA FORECAST DISCUSSION National Weather Service Raleigh NC 959 AM EST Sat Dec 18 2021 .SYNOPSIS... Bermuda high pressure will extend westward across the Southeast today, ahead of an approaching cold front. This cold front will cross central North Carolina early Sunday morning, bringing sharply colder air Sunday through Monday. Temperatures will return close to seasonal normals through mid week, as a low pressure system tracks from Florida northeastward along the Southeast coast. && .NEAR TERM /TODAY THROUGH TONIGHT/... As of 959 AM Saturday... Southwesterly flow persists at the surface and aloft this morning, as an anomalously moist airmass remains in place across the region. The widespread fog from earlier this morning continues to mix out, although it has been stubbornly persistent across the Triad. Meanwhile, a weak area of forcing for ascent is moving through the western Piedmont with showers moving through the western half of the forecast area. This is also helping to scour out the early morning fog and the Dense Fog Advisory will be allowed to expire as scheduled. The aforementioned showers will affect mainly the western 2/3rds of the area through this afternoon, with the Coastal Plain likely missing out on much of the rainfall. Rainfall amounts today will be light, generally a tenth to two tenths of an inch or less. Looking ahead a bit, much higher precip chances will enter the forecast this evening and overnight as stronger forcing for ascent moves into the area ahead of the approaching trough and surface cold front. PoPs in the likely/categorical range still look more than reasonable especially after midnight, with some of those values also extending past 12Z Sunday. High temps will remain mild with upper 60s in the Triad to mid 70s across the Sandhills/southern Coastal Plain. Record highs should not be jeopardized, although RDU may be in the ballpark for a record warm min temp as they only fell to 59 this morning (see Climate section below for more records). && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... As of 425 AM Saturday... Forcing for ascent is expected to peak Sun morning along and just ahead of the surface cold front, where upper divergence will be maximized within the juxtaposed LFQ of jetting to our SW and RRQ of jetting to our NE, and will carry likely (NW) to categorical (SE) pops Sun morning. Pops should trail off NW to SE behind the front in the afternoon as the deepest moisture and lift shifts off the coast, although skies may not clear entirely until Sun night, when the southern portion of the dampening mid level trough shifts overhead and to our E. Event QPF is expected to be one half to three-quarters of an inch. Temps will fall through the day, reaching the mid 40s to mid 50s near sunset, followed by lows in the mid 20s to lower 30s Sun night. -GIH && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 210 AM Saturday... The extended forecast period begins with high pressure over the Mid- Atlantic states which will weaken in place as a low develops across the southeastern United States. The GFS and ECMWF have been flip- flopping back and forth as to how far inland precipitation will make it from the low as it moves along the Atlantic coastline and eventually offshore. With the 00Z guidance, both models have come a little bit farther inland, although it's a little early to know if this trend will continue. Definitely went above NBM lows Tuesday night considering how warm the GFS and ECMWF are, but am not 100% sure at this point that all precipitation will fall as rain. It's too early to say anything other than that. Precipitation will end on Wednesday and once this low moves completely offshore, high pressure will build across the eastern United States, allowing for a dry forecast Thursday and Friday. Monday will be the coldest of the next 7 days, with highs in the mid to upper 40s. After that, highs should moderate into the 50s for the rest of the week. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... As of 650 AM Saturday... Overall aviation conditions will be poor today across central NC, particularly this morning and again starting late this evening. LIFR cigs and LIFR/IFR vsbys are commonplace across central NC at this hour, with a light wind from the SW. Cigs/vsbys will slowly improve through the morning, but are likely to get no better than MVFR over much of the area through mid afternoon, as SW winds pick up a bit to around 10 kts with infrequent gusts to 15-18 mph. A few light sprinkles or showers will move into the Piedmont, including INT/GSO/RDU between 16z and 21z. More numerous showers will spread into eastern sections (RDU/RWI/FAY) after 04z tonight, with cigs areawide dropping back down to IFR/LIFR. Cold front passage will send winds at INT/GSO shifting to northwesterly after about 08z. Looking beyond 12z Sun, the cold front will continue pushing to the SE through 14z, with steady showers in the morning over the Coastal Plain (RWI/FAY). This cold front passage will result in a wind shift to be from the NW then N and NE as a chilly high pressure ridge noses in from the N on Sun. Skies will finally clear out NW to SE Sun evening, with VFR conditions persisting through at least Mon. Low pressure tracking from N FL along the Southeast coast Tue into Wed may bring a return to sub-VFR conditions, especially at FAY/RWI, with a chance of rain. -GIH && .CLIMATE... Records DATE RDU GSO FAY High Hi Min High Hi Min High Hi Min 12/18 77 1984 55 1937 77 1924 53 1933 79 1924 62 1937 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Leins SHORT TERM...Hartfield LONG TERM...Green AVIATION...Hartfield CLIMATE...RAH