Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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114 FXUS62 KRAH 210016 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 815 PM EDT Sun May 20 2018 .SYNOPSIS... A moist and slightly unstable air mass will remain entrenched across central NC through the middle of the week. && .NEAR TERM /THROUGH TONIGHT/...
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As of 815 PM Sunday... Radar trends over the past half hour indicate that the slow moving convection over the western Piedmont is starting to weaken. With continue BL cooling, expect the bulk of this convection to dissipate over the next few hours. However, a sheared vorticity axis emanating northward from the broad cyclonic circulation center over the eastern Gulf of Mexico, along with the SE moving convection across northern/central VA, occurring ahead of a stalling sfc front, could support some a few showers near out NE and SW borders overnight. Overnight temperatures in the upper 60s-lower 70s, which will continue to challenge our record high mins.
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&& .SHORT TERM /MONDAY AND MONDAY NIGHT/... As of 330 PM Sunday... Monday-Monday night, a moist and slightly unstable air mass will remain entrenched over the region. A weak shear axis, the remnants of the nwd moving perturbation, may serve as a focus for isolated- scattered convection later in the morning. Another mid level perturbation is projected to lift nwd toward central NC Monday afternoon. This feature coupled with afternoon heating should trigger scattered convection across the entire forecast area, with the convective allowing models favoring locations along and north of highway 64. Based on relatively weak steering flow, the convection will be slow moving, and potentially dump locally excessive rainfall on a few locations. Afternoon temperatures will be dictated by when the convection fires as well as coverage. Temperatures across the south may warm into the low-mid 80s where convection may be limited, to the 70s/around 80 across the north where temperatures may be held in check by clouds/convection. Monday night, the northward drifting mid level perturbation will likely sustain scattered convection across the northern counties Monday evening, and potentially into the overnight hours along the I- 85 corridor. Again, the expected low movement of the convection may lead to localized flooding in a few locations. && .LONG TERM /TUESDAY THROUGH SUNDAY/... As of 230 PM Sunday... Maritime Tropical airmass will remain over central North Carolina through Wednesday with dewpoints in the upper 60s to lower 70s. Diurnal heating and embedded disturbances in deep southerly flow will contribute to scattered convection each afternoon and evening with a lull in activity late night into early morning. Any convection will have potential to produce very high rainfall rates given above normal PWs. High pressure building across the Northeast Thursday may push a backdoor cold front into the area Thursday and Friday bringing a drier airmass and much lower chances for convection, especially from Triangle and points north and east. Southerly flow returns Saturday bringing tropical airmass back into central North Carolina for the holiday weekend. Diurnal heating and embedded disturbances will generate more convection Saturday and Sunday. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... As of 714 PM Sunday... VFR Conditions continue at all TAF sites by the time of this issuance, with KINT/KGSO possibly dropping below between 715pm - 9pm due to local TSRA. Have maintained at least a TEMPO group at these sites while removing VCTS elsewhere where prob is much lower for ltng Sunday Night into Monday. Things settle down overnight, with the next potential sub-VFR conditions arriving early morning in the way of low clouds/fog. Highly uncertain on where this will form at this time, as a BKN/OVC mid to high level CIG should remain in place overnight. Best chance will occur at sites who saw precip Sunday evening, so have left mention of MVFR BR in at KINT/KGSO. A moist and slightly unstable air mass will maintain marginal aviation conditions through mid week. MVFR-low end VFR ceilings expected across the region through Monday evening with the highest chances for adverse ceilings during the early morning hours, and in the afternoon in proximity of scattered convection. The atmosphere will support the development of scattered afternoon-evening showers and thunderstorms through mid week. On Monday, it appears the highest concentration of convection will be across the northern Piedmont into the Coastal Plain, affecting most of the TAF sites. For now, have VCTS arriving everywhere by 18z. This will need massaging during later TAF issuance`s when geographic confidence improves. Scattered convection is fairly certain to occur each afternoon and evening through the remainder of the work week. In addition, patchy early morning low clouds will likely occur each morning. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...CBL SHORT TERM...WSS LONG TERM...Franklin AVIATION...JJM/WSS is the U.S. government's official web portal to all federal, state and local government web resources and services.