Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 141850 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 250 PM EDT Mon Aug 14 2017 .SYNOPSIS... A front stalled across portions of central North Carolina will gradually wash out and dissipate by mid-week. && .NEAR TERM /THROUGH TONIGHT/... As of 145 PM Monday... Challenging forecast. Central NC remains situated at the southern periphery of the westerlies in SW flow aloft. Upper level forcing will be limited to small amplitude waves progressing across the far N/NW Piedmont. The cold front that progressed southward into central NC yesterday remains stalled over the region. At 17Z, the boundary was located over portions of the Sandhills and Coastal Plain, extending (roughly) SW-NE from Wadesboro to Rocky Mount. The boundary should remain nearly stationary through tonight, though some meandering is likely in assoc/w differential heating and convective outflow this afternoon. Regardless, forcing assoc/w this feature will be very weak in nature and confined to shallow convergence. Diurnal destabilization is expected to yield marginal MLCAPE (250-500 J/kg) in the north (weakest along/north of I-85) to moderate MLCAPE (1000-1500 J/kg) in the south (strongest near the NC/SC border) this afternoon. With the above in mind, expect the best potential for convection in the N/NW Piedmont where episodic DPVA will augment forcing and offset weaker instability. Further S/SE, instability will be greater, however, coverage is likely to be isolated in nature due to weak forcing. The latest guidance suggests small amplitude waves are most likely to traverse the region this evening/overnight, and convective coverage may be greatest after sunset. Expect highs ranging from the upper 70s to lower 80s near the VA border to upper 80s /90F/ near the SC border. Lows tonight in the lower/mid 70s, warmest S/SE. -Vincent && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... As of 145 PM Monday... With little change in the synoptic pattern, expect conditions similar to today, though a fair amount of uncertainty persists w/regard to the spatial/temporal extent of cloud cover, convection, and high temperatures. Like today, convective coverage/timing may largely be dictated by small amplitude waves in WSW/SW flow aloft. With the above in mind, will indicate a 50% chance of showers/storms across the area, primarily during the aft/eve hours, with highs in the mid 80s (N) to ~90F (S) and lows in the lower/mid 70s. -Vincent && .LONG TERM /WEDNESDAY THROUGH MONDAY/...
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As of 250 PM Monday... A weak wave in the otherwise zonal flow aloft will provide support for an uptick in the shower/tstm coverage on Wednesday, with the existing sfc trough across the Carolinas to serve as a low level focus. Once this wave exits to our east, the sfc trough will also move eastward, and subsidence in the wake of these features should set the stage for a mostly dry and warmer daytime on Thursday. This break in the precip chances will be short-lived, as the next wave in the fast upper flow will approach Thursday night, along with the next sfc front which is progged to move into the western Carolinas Friday morning. Once again, look for an uptick in shower/tstm coverage along and ahead of the front, so chance PoPs are in order for central NC on Friday and again on Saturday, but highest PoPs on Saturday across our eastern half given the boundary positioned across the center of the state. During the latter half of the weekend, a more substantial short wave trough will move across the Mid-Atlantic region, thus enhancing our rain chances yet again Saturday night into mid-day Sunday, before shifting east and pushing the cold front to our south by late Sunday. Looking ahead to next Monday and eclipse weather...of course long- range forecasts are always subject to change, but todays models suggest at least partly cloudy conditions for central NC, with veering low level flow on the southern periphery of high pressure transiting the Mid-Atlantic. Rain chances appear to increase southward and closer to the aforementioned cold front stalled to our south. Temps during the long term period will be largely a function of cloud coverage and rain chances. On the days with lesser of both, look for highs up around 90, but on the cloudy/wetter days, highs in the mid-upr 80s. Uniform low temps, in the low-mid 70s.
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&& .AVIATION /18Z MONDAY THROUGH SATURDAY/... As of 145 PM Monday... 24-hr TAF Period: As of 17Z, LIFR ceilings persisted at the INT/GSO terminals, though RDU/RWI have improved to MVFR and FAY to VFR. Expect further improvement mid/late afternoon, with VFR conditions possible at RDU/RWI/FAY terminals (esp FAY). LIFR conditions at the INT/GSO terminals should improve to IFR and possibly MVFR mid/late afternoon, though confidence is lower. Convection could potentially affect any terminal this aft/eve, though the relative best chance should be at the INT/GSO terminals. With little change in pattern/ airmass, IFR/LIFR ceilings are expected to re-develop at all terminals late this evening/tonight. Winds will be light/variable throughout the TAF period. Looking Ahead: With relatively little change in the synoptic pattern, adverse conditions associated with diurnal convection (primarily 18-03Z) and early morning stratus (primarily 06-15Z) are likely to persist through mid-late week. -Vincent && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Vincent NEAR TERM...Vincent SHORT TERM...Vincent LONG TERM...np AVIATION...Vincent

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