Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 070651 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 151 AM EST Thu Dec 7 2017 .SYNOPSIS...
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Cool high pressure will extend across the Carolinas through Saturday, while an upper level trough amplifies sharply west of the Appalachians and moves slowly eastward.
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&& .NEAR TERM /THROUGH TONIGHT/... As of 910 PM Wednesday... The westward-inland resurgence of precipitation this evening is in response to shortwave energy streaming NE across the area, within the energetic SW flow aloft. Precipitation, which has occasionally and briefly been mixed with some very light sleet/wet snow over the central Piedmont counties, is falling from a 7 to 9 kft cloud base. However with temperatures overnight remaining well above freezing, cooling down only into the upper 30s to lower 40s, any frozen precipitation will prove inconsequential. Latest radar trends indicated back-edge of precip is starting to shift slow eastward, and should continue to push east towards the coastal areas(east of I- 95) by daybreak. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... As of 110 PM Wednesday... Forecast remains nearly unchanged with a persistent southwesterly flow aloft, deep moisture, and multiple disturbances riding northeast over a baroclinic zone off the southeast coast. Light rain is expected on Thursday and Thursday night across the Coastal Plain and Sandhills, mainly south and east of Raleigh. With colder air working into the region, there is a chance that some of the precipitation will mix with or change to snow. It`s important to note that the pattern suggests an active period with widespread precipitation across coastal NC and decreasing amounts and coverage to the north and west in the more climatologically colder region of the northwest Piedmont. In addition, there is no well defined surface high to support the delivery of cold and dry air into central NC to support more than a low end event. Still, partial thickness values and forecast BUFR soundings support some wet snow across the northwest and northern Piedmont including the Triad area Thursday night with surface temperatures dropping into the 32 to 36 range. But given these areas are on the northwest fringe of the precipitation shield and PoPs are in only the chance range, no snow accumulation is expected. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... As of 305 PM Wednesday... ...Increasing chance of snow across portions of Central NC between midnight and 7 AM Saturday, with some accumulation on elevated and grassy surfaces possible... Friday and Friday Night: Central NC will be under the influence of deep southwesterly flow aloft as a strong upper level trough to the west swings eastward toward the region. Disturbances in the flow aloft will move over the area, resulting in periods of heavier precipitation. At the surface, Central NC will be sandwiched between the stalled front off the Mid-Atlantic coast and high pressure ridging eastward from the west. With the high in an unfavorable location, the best push of cold air will likely get hung up along the mountains. Expect much of the precipitation to fall as rain, especially early on. Despite the delayed CAA, strong lift in a saturated dendritic growth zone will likely result in precipitation rates strong enough for snow to occur where temperatures are in the 32-36 degree range. This will be an event where the cold air is chasing the precipitation, thus expect most of the precipitation to fall as liquid. Liquid equivalent precipitation totals will range from less than a quarter of an inch in the northwest to nearly 1.75 inches in the southeast. Given the warm ground and boundary layer, snow will have a difficult time accumulating except for on elevated and grassy surfaces and under high precipitation rates. Generally less than an inch of snow is expected at this time, primarily between midnight and 7 AM Saturday. Best chances for accumulating snow along a line from Lexington to Burlington to Roanoke Rapids, generally be along and west of US-1. Highs on Friday in the low to mid 40s with overnight lows in the upper 20s NW to mid 30s SE. Temps are not expected to fall below freezing in the Triad until after midnight. Saturday through Wednesday: As the strong upper disturbance swings through the region Saturday morning, the main precipitation axis will shift east of the area. At the surface, in the wake of the disturbance aloft, west-northwest flow will advect strong cold air into Central NC ahead of a secondary strong vort max aloft diving southward over the area. Saturday and Sunday will be the coldest days Central NC has had in a while, with highs in the low to mid 40s and overnight lows in the low to mid 20s (possibly dipping below 20 in outlying areas Sunday night). Generally dry weather expected for the remainder of the period although a few sprinkles/flurries early next week cannot be ruled out. Temperatures will moderate a bit Monday and Tuesday before another cold front moves through the area. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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As of 130 AM Thursday... A lead disturbance in wswly flow aloft --and associated light, VFR rain-- will continue to move east and away of cntl NC during the next several hours. Ceilings, but of the VFR, mid-high level variety, will otherwise persist throughout the TAF period. The approach of a disturbance upstream/over the srn Plains will cause these ceilings to lower --into low VFR or high-end MVFR range and with the re-development of light rain at FAY/RWI/RDU-- this evening. Surface winds will be light and variable, to occasionally nly on Thu, as high pressure extends directly over the Carolinas. Outlook: An upper level trough will amplify west of the Appalachians, with associated periods of precipitation and sub-VFR conditions expected to persist through early Sat, mainly at FAY/RWI/RDU. Some of that precipitation may mix with or change to snow Friday night-early Sat at Piedmont sites, particularly at RDU and perhaps GSO if the precipitation shield ultimately extends that far wwd.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...CBL SHORT TERM...BLAES/Franklin LONG TERM...KC AVIATION...MWS is the U.S. government's official web portal to all federal, state and local government web resources and services.