Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 231603 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1103 AM EST Fri Feb 23 2018 .SYNOPSIS...
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A strong sub-tropical ridge aloft situated off the Southeast U.S. coast will weaken while drifting south toward the Bahamas through Saturday. Meanwhile, a quasi-stationary front over s-cntl NC this morning will retreat slowly nwd through this evening, then more appreciably so as it dissipates on Sat.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 1100 AM Friday... AT 16Z, the surface cold front was analyzed from just northeast of ILM, nwwd to near SOP, where it had become stationary from there wwd to near IPJ. Associated surface temperatures ranged from mid-upr 40s across the far nrn Piedmont and Coastal Plain (46-48 at TDF/HNZ/IXA) to around 70 degrees in the srn Piedmont (70-72 at AFP/RCZ/MEB). 12Z upr air data and pilot reports indicate the overcast layer over the Piedmont is relatively thick, between 1-2 k ft deep; and visible satellite imagery this morning indeed reveals a thick blanket of low cloudiness there. To the south, and even behind the front, over the Sandhills and srn and cntl Coastal Plain, the moist layer is more shallow and thinner and will be more readily eroded/mixed out with diurnal heating/mixing during the next few hours. This erosion will subsequently cause the srn fringe of the thicker ovc to the north to likewise erode and allow the surface front to retreat slowly nwd through the Highway 64 corridor mid-late afternoon, with associated late day sun and warming into the upr 60s/around 70 degrees there, though not the persistence upr 70s to around 80 degrees that are expected in the current warm sector over srn NC. Meanwhile, the low clouds and much cooler conditions are expected to persist across the nrn Piedmont and nrn Coastal Plain, with many locations nw of I-85 likely to hold in the 50s, to perhaps around 60 degrees, throughout the day. While the low clouds may briefly scatter even in these far nrn areas this evening, the associated remnant wedge air mass there will make those same areas most susceptible to the earliest development of very low overcast and fog tonight, with that occurrence likely to be delayed until very late tonight-early Sat morning elsewhere - similar to previous mornings. Low temperatures are expected to range from low-mid 50s in the remnant wedge regime to around 60 degrees in the srn Coastal Plain.
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&& .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... As of 325 AM Friday... While slightly dampened, the subtropical ridge over the SE US will continue to be the dominate weather feature over the region, deflecting the better rain chances west of the area, with a continuation of record warmth in both daytime highs and warm nighttime lows. Shortwave disturbances, ejecting NE in the SW flow aloft, ahead of the shortwave trough lifting from the Rockies into the Northern Plains and Upper Midwest, could support a stray shower or two, especially across the NW Piedmont. Otherwise it remain mostly dry with a mixture of clouds in the morning, and some sun by the afternoon. Breezy SWLY winds will develop by the afternoon and will continue into the evening and overnight as a 40 to 50 kt low-level jet spreads in from the west. Highs in the 75 to 80. Lows in the 60s. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 345 AM Friday... The Long Term period continues to look active, with two pertinent weather systems likely to impact the forecast area. Warmer than normal conditions Sunday afternoon will be replaced with more seasonable values by Monday afternoon and likely persisting through at least Thursday. A strengthening mid latitude cyclone will progress north and east across the Great Lakes on Sunday inching an associated cold front east of the mountains. A relatively strong area of high pressure over the western Atlantic will slowly slide east, allowing the front to cross through portions of central North Carolina before stalling across our area. Some significant model differences when it comes to how far the front will make it east, with the GFS consistently showing a more vigorous initial surge with the boundary, stalling the front closer to the coast. The ECMWF on the other hand stalls the front further inland, allowing a disturbance to develop Sunday night into Monday, spreading higher QPF amounts across the forecast area. Have tried to blend the two solutions, allowing POPs to linger through Monday evening, and notching the average QPF amount closer to a half inch between Sunday and Monday. High pressure will build into the mid Atlantic briefly Tuesday and Wednesday, allowing the sun to re-emerge and drier conditions along with more seasonable temperatures to win out albeit briefly. Cloud cover will be on the rise by Wednesday morning as a warm front lifts north through the Carolinas, once again introducing showers that will likely persist through Thursday night. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... As of 643 AM Friday... 24-Hour TAF Period: The back-door cold front will briefly stall over the area this morning, before retreating north into VA this afternoon and evening. LIFR to MVFR ceiling across the northern terminals will persist through the morning, gradually lifting and scattering out during the afternoon. Expect a brief period of ENELY winds behind the front through 15z, becoming southerly by the late afternoon and evening. Will follow a persistence forecast overnight, with areas of stratus and fog(south) developing overnight. Looking ahead: The sub-tropical ridge will weaken and drift south, but maintain influence over the Carolinas. As a result, 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. Isolated to scattered showers are possible Saturday afternoon, especially at KINT and KGSO. However, the better 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 ------------------------------------------ 02/23 79 1980 57 1962 02/24 81 1982 58 1985 GSO Records: Date | High Year | High Min Year ------------------------------------------ 02/23 74 2017 52 1922 02/24 79 1982 55 1985 FAY Records: Date | High Year | High Min Year ------------------------------------------- 02/23 80 1922 55 1922 02/24 83 1930 60 1975 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...CBL LONG TERM...JJM AVIATION...CBL/MWS CLIMATE...RAH

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