Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 132053 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC Issued by National Weather Service BLACKSBURG VA 353 PM EST Tue Feb 13 2018 .SYNOPSIS...
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Cool surface high pressure over the Mid-Atlantic will weaken and drift over the southeast coast later Wednesday and allow weak southwest flow to return and bring milder but continued moist weather through the remainder of the week. The next cold front is expected to arrive by the weekend.
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&& .NEAR TERM /THROUGH WEDNESDAY/...
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As of 350 PM Tuesday... A ridge of surface high pressure along the mid-Atlantic Coast into central North Carolina this evening will slowly drift south and weaken over South Carolina by late Wednesday. This will allow the cool stable wedge to begin to slowly erode, but not until late Wednesday most likely. In the meantime, expect low clouds and near steady temperatures overnight, with a few showers along and east of I-95 corridor associated with a zone of weak isentropic lift over the wedge. This expected to move east pretty early in the evening, but may leave some lingering sprinkles or drizzle for a few more hours into the later evening. Confidence on lingering drizzle or development of anything more than light fog, mainly east of I-95, is fairly low so have only indicated slight chance for showers though about midnight. Wednesday with the weakening high drifting south there may be an opportunity for some peaks of sun and breaking of inversion but there is not especially strong southwest flow above the inversion and likely bias of most guidance is to break this up and warm temperatures too soon. Leaned closer to NAM and some of the higher res models on temps for the daytime, but with some compromise upward. Weak upper wave in zonal flow aloft moves in from the west by mid day and question is how far east will showers make it across the Appalachians. Best chances across the northwest half of the forecast area for any showers in the afternoon but did not see reason to go with PoPs higher than mid chance category with only very light precip at best through the daytime hours.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
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As of 300 PM Tuesday... Wednesday night into Thursday, high pressure will remain situated off the southeast U.S. coast. Anti-cyclonic flow around this high will draw moisture north from the western Gulf of Mexico into the Tennessee Valley then eastward to along the VA/NC border. Western and northern sections of the forecast area are expected to experience some scattered showers during this time frame in association with this moisture feed and weak upper level disturbance passing over the region. By Thursday night, the weak disturbance will be northeast of the region, bring a brief break in the activity across the western and northern sections. Thursday night into and through Friday, our focus turns northwest of the area as a cold front heads southeast into TN/WV/VA. Look for increasing chances of showers, especially across northwest sections of the region, Friday afternoon. The cold front crosses the entire forecast Friday night with its associated showers. Temperatures across the region will trend milder during this portion of the forecast with readings averaging some 20 degrees or more above normal by Friday.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/...
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As of 300 PM Tuesday... Temperatures trend colder for the weekend behind cold front, but still average about five degrees above normal through Sunday. A cold rain is forecast for Saturday as the front makes limited progress south of the region before a disturbance moves along it, bringing rain showers back to the area after a brief break late Friday night into early Saturday morning. A shortwave trough will progress through the Great Lake region Saturday night into early Sunday. This feature will be the kicker to help the cold front off the southeast U.S. coast with surface high pressure building into the area from the northwest. Temperatures will start to moderate again Monday into Tuesday as the center of the high pressure shifts east of the area, and low level flow shifts southwest. Guidance offers a solution of a warm front heading north across the area on Monday, Monday night, and Tuesday. This will bring a return of some light rain to the area, especially western and northern parts of the area. By Tuesday, temperatures some 15 degrees above normal are forecast.
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&& .AVIATION /21Z TUESDAY THROUGH SUNDAY/... As of 1258 PM Tuesday... Wedge remains in place with mainly VFR ceilings and northeast winds but gradient is relaxing a bit this afternoon and so expect most winds to remain below 10 kts or only briefly gust to that level the remainder of the afternoon. Ceilings should begin to slowly drop into MVFR range later this afternoon and especially into the evening, and confidence is moderate that they will remain MVFR. There is a possibility for some temporary IFR ceilings at RWI and maybe FAY. If showers develop a little more later this afternoon and as far west as RDU, but most likely they will stay just east of RDU, that could result in evening ceilings dropping into the IFR category as the showers move east and sun goes down. Winds very light to nearly calm overnight. By morning the wedge should begin to slowly erode and ceilings should lift back to VFR and become broken at during the morning. Winds will remain light but shift more southwesterly as wedge erodes. Outlook: After the wedge erodes and the area is in the warm sector by Wed night, this will allow an increasingly moist air mass to expand across the southeastern and middle Atlantic states through mid to late week, which will result in periods of sub-VFR conditions, particularly during the overnight and morning hours, through the end of the week. && .CLIMATE... RDU Records: Date | High Year | High Min Year ------------------------------------------ 02/15 | 82 1989 | 61 1989 02/16 | 77 1976 | 62 1990 GSO Records: Date | High Year | High Min Year ------------------------------------------ 02/15 | 78 1989 | 57 1949 02/16 | 76 1927 | 58 1990 FAY Records: Date | High Year | High Min Year ------------------------------------------- 02/15 | 81 1918 | 63 1918 02/16 | 82 1989 | 62 1935 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...99 NEAR TERM...99 SHORT TERM...99 LONG TERM...99 AVIATION...MWS/99 CLIMATE...

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