Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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420 FXUS62 KRAH 240527 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 125 AM EDT Wed May 24 2017 .SYNOPSIS...
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A warm and moist air mass will hold over the area tonight. A warm front will lift north through North Carolina Wednesday, then a cold front will cross the area late Wednesday night through Thursday morning, followed by passage of a strong upper level trough Thursday afternoon. Quiet and dry weather will return Friday.
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&& .NEAR TERM TONIGHT/... 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. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... 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. && .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 /06Z Wednesday through Sunday/...
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As of 125 AM Wednesday... IFR to LIFR conditions will dominate across central NC through mid morning, as a warm moist air mass combined with light surface winds supports low stratus. FAY, however, will see a few periods of MVFR to VFR clouds through this morning. Cigs are expected to rise to MVFR, with mostly VFR vsbys, by late morning (around 15z), perhaps reaching low-end VFR by early to mid afternoon (around 18z) as a warm front surges northward through the area with increasing mixing. Patchy light showers are expected through early afternoon, followed by more widespread showers/storms moving in from west to east during the mid to late afternoon. A period of IFR conditions in heavy showers and storms with gusty erratic winds are possible at all sites after 18z at INT/GSO and after 19z RDU/FAY/RWI, then MVFR to IFR conditions will likely last from 02z until the end of the TAF valid period with lingering rain. Some storms this afternoon into early evening may be strong to severe, with large hail and intense wind gusts. Looking beyond 06z early Thu morning, MVFR conditions are likely to dominate late tonight with decreasing rain chances from west to east overnight. Cigs should rise to VFR after 13z Thu, but there will be a good chance for showers with small graupel/hail during the day Thu as the axis of a powerful mid level trough swings through the area. Skies will clear out late Thu night, then VFR conditions should dominate Fri through Sun, although there will be a chance for a few storms late Sat into Sun as a cold front approaches. -GIH
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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...Hartfield NEAR TERM...Badgett SHORT TERM...MWS/Franklin LONG TERM...MWS/Franklin AVIATION...Hartfield

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