Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 240046 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 842 PM EDT Tue May 23 2017 .SYNOPSIS...
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A series of low pressure systems will track along a nearly stationary front over central NC through Wednesday night, causing periods of showers and thunderstorms. Improving weather conditions are anticipated by late in the week.
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&& .NEAR TERM TONIGHT/...
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As of 842 PM Tuesday... ...Flood watch has been extended through Wednesday night ... Even though the Flood Watch is in effect through Wednesday night, there should be a lull in the significant rainfall for a period this evening into the overnight hours over the southern and eastern zones (Sandhills and Coastal Plain) - just behind a departing meso-low that brought the round of heavy rain and even the isolated tornado down south near Autreyville late afternoon. This weak low was currently over NE Johnston/Wilson County, moving NE along the nearly stationary boundary extending up into NE NC near Elizabeth City. The main area of heavy rain/isolated thunderstorms was pushing east and will be out of the Wilson, Tarboro, and Goldsboro areas by 9-11 pm or so. Radar confirmed the expected lull just in the wake of this departing system, with only scattered lighter showers expected through 200-400 am in the east and south. The nearly stationary boundary extended SW of the departing wave of low pressure through the Sandhills to near Charlotte into north Georgia. Additional widespread convection associated with the next wave upstream over GA extending into western NC is expected gradually weaken with time through the overnight hours. However, with the front lingering in place and dew points in the 70 degree range, with inflow from the south, the convection may be able to sustain itself longer than is forecast by the current hi-res models. For now, we will continue to carry chance POP overnight - except likely in the NW where more widespread showers are expected along and north of the boundary aided by the ENE flow combined with more upper support with the disturbance aloft tracking east across the central Appalachians. A general low overcast with areas of fog is expected overnight. Lows should hold in the upper 50s N but range into the upper 60s to near 70 south (where the juicy air resides just south of the front). Widespread convection is expected again, mainly Wednesday afternoon and night associated with the next strong vorticity maximum crosses the TN Valley and rolls out of the Mountains late in the day.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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As of 225 PM Tuesday... A complex pattern will result at the surface on Wednesday and Thursday. A frontal zone will likely be draped northeast to southwest marking the southern periphery of weak ridging/CAD/low overcast extending across most of Virginia and North Carolina at the start of the day Wednesday then extending Northwestward as a warm front to a low over the western Ohio Valley. That front, acting as the edge of the CAD regime, and focus for convection, will then likely retreat northward with a narrow wedge of a warm sector airmass through southern and perhaps portions of eastern portions of the area during the day Wednesday, then through the remainder of central North Carolina early Wednesday night, all immediately ahead of a triple point low that will develop and migrate across the western Carolinas very late Wednesday afternoon and Wednesday night. Initial CAD conditions, and subsequent convection along the retreating warm front, will tend to slow the retreat of the unstable warm sector and north boundary for any severe threat through much of Wednesday, such that any strong to severe potential will likely remain from Wadesboro to Goldsboro and Rocky Mount and points southeast. That unstable warm sector should then surge Northward through the remainder of central North Carolina early Wed night, immediately ahead of the triple point low, yielding brief, but likely sufficient, weak destabilization to support surface-based QLCS storms capable of producing both swaths of damaging straight line winds and isolated tornadoes along embedded mesovortices/bows/lewps. The cold/occluded front will cause the warm sector and associated severe threat to collapse eastward and through the Coastal Plain late Wednesday night. Brief drying and clearing will be probable through early midday Thursday, but clouds will redevelop with heating, with an additional band or bands of convection in fast, cyclonic, and Cold Air Advection bearing flow aloft, which will spread northeastward across central North Carolina through late afternoon. The western edge may result in a strongly forced line of storms along the eastern periphery of focused forcing for ascent accompanying the aforementioned upper trough/low. Cold temperatures and steep lapse rates aloft will favor small hail in even marginally strong cores; and a 50-70 kt South-southwesterly speed max on eastern fringe of the upper trough will support organized storm modes, including low- topped (splitting) supercells, given long and relatively straight forecast hodographs, which would be capable of producing severe hail and damaging straight line winds.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... As of 225 PM Tuesday... Dry conditions will return by Thursday night, as the upper trough lifts away and weak high pressure expands across the sern states through early Sat. A warm front will develop newd across the central Appalachians later Saturday and across the Middle Atlantic states by Sunday, with a return to warmer and more humid conditions, and a chance of convection over the weekend into early next week. && .AVIATION /00Z Wednesday through Sunday/...
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As of 842 PM Tuesday... Ceilings are expected to remain LIFR to IFR through the period, with visibilities MVFR to VFR except in the heavier rain showers. The most concentrated showers are expected in the NW around KGSO and KINT through 06z before tapering to areas of drizzle. Although there will be a lull in precip/convection until the arrival of the next surface wave late Wednesday afternoon/evening ceilings are expected to remain IFR to MVFR. A closed upper low digging into the southern Appalachians Wednesday night will bring another round of heavy showers and a few potentially strong thunderstorms to the area late Wednesday afternoon/evening, lingering into the predawn morning hours on Thursday. Outlook Late Thursday through the weekend... Improvement to mostly VFR is expected by midday Thu, although scattered afternoon showers generating MVFR conditions are possible. VFR conditions should return for Fri/Sat as a weak high pressure ridge extends into the area.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... Flood Watch through late Wednesday night for NCZ007>011-021>028- 038>043-073>078-083>086-088-089. && $$ SYNOPSIS...Badgett NEAR TERM...Badgett SHORT TERM...MWS/Franklin LONG TERM...MWS/Franklin AVIATION...Badgett/CBL

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