Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 220915 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 415 AM EST Thu Feb 22 2018 .SYNOPSIS... Strong high pressure will gradually weaken tonight and Friday, allowing a backdoor cold front to stall in the vicinity of northern NC on Friday, before retreating north as a warm front Saturday. && .NEAR TERM /THROUGH TONIGHT/... As of 410 AM Thursday... Today: Unseasonably warm conditions associated with the persistent strong subtropical ridging centered off the south Atlantic coast will support another day of record setting warmth across central NC. Much like yesterday, morning stratus will initially temper daytime heating, with eventual lifting and scattering of the stratus deck by late morning and into the early afternoon. Afternoon highs again in the mid 70s NW to lower 80s SE. Additionally, will see some occasional wind gusts into the mid to upper teens, especially during the afternoon. Tonight: Shortwave energy rounding the crest of the subtropical ridge over the Ohio Valley and northern Mid Atlantic states will weaken/dampen the subtropical ridge just enough to allow the northern end of the wavy frontal zone to sink slowly south through central and southern VA by the evening, and will attempt to move into northern portions of the state tonight/Friday morning. The NAM remains the most aggressive in pushing the front through the northern half of the CWA by daybreak, while the GFS and EC stall the front near the NC-VA border, before quickly retreating north as a warm on Friday. Spotty showers will be possible along the front, with the shallow cool air making for a very sharp north-south temp gradient in overnight lows, ranging from upper 40s/lower 50s NE to near/lower 60s south. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 410 AM Thursday... Low Confidence in Friday`s forecast across central and northern Piedmont and Coastal Plain. Challenging forecast give the model discrepancy in the location of the back-door cold front Friday morning, with the NAM indicating a brief reprieve from the anomalous warmth, at least across the northern half of the forecast area, via a shallow in-situ wedge north of the boundary. Meanwhile, the GFS and EC stall the front briefly along the VA-NC border, keeping all of central NC in the warm sector. Huge bust potential wrt forecast highs Friday. If the NAM is correct, northern areas will struggle to get out of the 50s with some patchy drizzle possible through the first half of the day. Meanwhile, areas south of the front will once again warm into the mid to upper 70s. Am not ready to go quite that cool across the northern Piedmont, but have certainly trended towards the cooler guidance. Conversely if the GFS and EC verify, all of central NC will see another day of near record warmth with mid 70s to lower 80s everywhere. Lows Friday night ranging from mid 50s north to lower 60s south. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 330 AM Thursday... An unsettled pattern returns by the weekend, as a surface low is expected to strengthen across the central Great Plains States Saturday and eject northeast through the Great Lakes region on Sunday. This will push an associated cold front through central North Carolina Sunday and Sunday night before stalling it along the Carolina coast Monday. This front will re-introduce showers to the area as early as Saturday afternoon in the form of light pre-frontal showers, with the best coverage of rain, including the possibility of a rumble of thunder, arriving Sunday afternoon and evening as the front progresses through. Another wave will intensify along the front Monday and Monday night, spreading an additional wave of precipitation into the area. Some uncertainty here on just how far west this precipitation will spread, with some significant differences in the ECMWF/GFS solutions. The European solution tends to spread a greater amount of QPF inland, mainly due to a much slower progression of the original front, while the GFS keeps the bulk of the precip east of Interstate 95. For now, have kept PoPs higher in the southeast and lower in the northwest for this time period. High pressure builds in Tuesday and the first part of Wednesday keeping the area drier and temperatures much closer to normal for this time of year. The high will push offshore Wednesday afternoon ahead of a developing southern stream system set to introduce another round of rain chances Wednesday night into Thursday. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... As of 1252 AM Thursday... 24-Hour TAF Period: Southerly return flow between the offshore high pressure and a cold front approaching from the NW will continue to support an unseasonably warm and humid airmass, which will be prone to widespread stratus development, with MVFR generally between 06Z and 09Z Thursday, then subsequently dropping to IFR/LIFR between 09Z and 15Z, with the best chances at KFAY, then KRWI and less so at KRDU, KGSO, and KINT. Generally expect clouds to scatter out with bases in the 2-4 kft range by Thursday afternoon, though there is a chance KINT and KGSO terminals could stay broken into the afternoon. South- southwesterly winds will persist through the period, generally 5 kts or less overnight and 5-10 kts during the day Thursday. Looking ahead: A backdoor cold front will settle into at least nrn NC late tonight/Friday morning, roughly along or just north of US Highway 64. This boundary will result in a more prolonged period of IFR-MVFR ceilings along and north of it through most of the day Fri. Thereafter, a persistence forecast of late night-morning stratus and fog, lifting and scattering to high MVFR- low VFR each afternoon, will generally continue through the weekend. The next chance of rain will accompany a frontal zone that will settle into and possibly stall over the Carolinas late Sun into early next week. && .CLIMATE... RDU Records: Date | High Year | High Min Year ------------------------------------------ 02/22 75 1897 60 1897 02/23 79 1980 57 1962 02/24 81 1982 58 1985 GSO Records: Date | High Year | High Min Year ------------------------------------------ 02/22 74 1925 57 1980 02/23 74 2017 52 1922 02/24 79 1982 55 1985 FAY Records: Date | High Year | High Min Year ------------------------------------------- 02/22 77 2003 56 1989 02/23 80 1922 55 1922 02/24 83 1930 60 1975 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CBL NEAR TERM...CBL SHORT TERM...CBL LONG TERM...JJM AVIATION...CBL/MWS CLIMATE...RAH

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