Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 282259 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 700 PM EDT Fri Jul 28 2017 .SYNOPSIS... A cold front will approach from the northwest tonight, and cross our region overnight through Saturday morning . Cooler and drier air will filter into the area through the weekend and will linger through the early part of next week. && .NEAR TERM /LATE AFTERNOON THROUGH TONIGHT/... As of 310 PM Friday... Little change required to the near term forecast. Scattered convection gradually developing at mid afternoon with the highest convective coverage expected between 22Z-06Z. Atmosphere has become moderately unstable with sfc based CAPE around 3000 J/kg across the Piedmont and Sandhills, thanks to afternoon temps near 90/lower 90s. Latest meso-analysis suggest SBCAPE may go as high as 4000 by late afternoon across the eastern counties. This buoyant air mass coupled with increasing effective bulk shear of 30- 35kts suggest an increased potential for organized convection late this afternoon-early evening in the form of broken convective segments and attendant locally damaging wind threat. Enhanced low level helicity will be found close to the VA border where an old outflow boundary resides. Any storms with sufficient updrafts that intersect or cross this boundary will begin to rotate and potentially produce a weak tornado threat through the evening hours. Still appears that the greatest convective coverage will occur between 22Z and 04Z, with coverage diminishing west-to-east during the overnight hours. A surface cold front will enter our nw counties well after midnight. Thus, most locations will retain the muggy air mass, yielding minimum temperatures primarily in the low-mid 70s. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... As of 310 PM Friday... The sfc cold front will slowly drift sewd Saturday, maintaining a threat for scattered showers and storms across our far eastern-se counties. The bulk of the storms will remain below severe criteria though gusty winds will be common with the storms. The strengthening s/w responsible for our active weather tonight will be in close proximity to our northern counties Saturday, triggering scattered showers and possibly a t-storm or two. Expect the higher concentration of showers in vicinity of the VA border. The s/w will cross our region Saturday night, possibly accompanied by a few showers, primarily northeast and east of Raleigh. A notably drier air mass will gradually overspread central NC late Saturday and Saturday night, leading to less humid conditions. A mixture of sun and clouds and a steady ne flow will result in cooler max temps Saturday. The clouds are expected to be more extensive north-northeast compared to the southwest. High temperatures upper 70s-lower 80s north to mid-upper 80s south. Min temps Saturday night low-mid 60s. && .LONG TERM /SUNDAY THROUGH FRIDAY/... As of 1245 PM Friday... Bit of a change in the way ECMWF handles the east coast trof later this weekend. Latest shows much more progressive movement, with the trof lifting out quickly early Sunday, in contrast the GFS`s slow rotation across the area through Sunday night. Not a huge problem, mainly would affect the sky coverage, with the ECMWF clearing us quickly while the GFS`s later solution would produce some isolated lingering showers in the northeast early Sunday. After this trof exits, a pleasantly dry and cooler airmass will be in place, with very gradual warming through the midweek. Seasonal conditions return Thu and Fri as weak return flow nudges humidity and warmer temperatures up the coast. Highs will start off Sunday from the upper 70s across the north to lower 80s in the south. These highs will warm to the mid 80s on Tuesday, then to around 90 Thursday and Friday. Morning mins will be pleasant...in the low to mid 60s through midweek, warming to around 70 by Friday morning. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
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As of 700 PM Friday... Scattered convection and associated MVFR/IFR parameters will occur in the vicinity of most TAF sites across central NC through midnight. The stronger storms will produce small hail and wind gusts up to 40 mph. A sfc cold front will slowly drift sewd across central NC overnight into Saturday morning. The frontal passage will be noted by the sfc winds veering to a nly direction. Expect scattered showers and a few t-storms to occur ahead of the front overnight into early Saturday, primarily in vicinity of KFAY and KRWI. An upper level s/w will cross overhead late Saturday into Saturday night. This feature may trigger scattered showers in vicinity of KRDU, KRWI, and KFAY Saturday afternoon through Saturday evening, as well as periods of MVFR ceilings. Surface winds Saturday will be breezy with gusts close to 20 mph from the north northeast. The gusts will be most common in vicinity of KFAY and KRWI. Once this feature exits our region Saturday night a drier more stable air mass will overspread the region, leading to an extended period of VFR parameters.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CBL NEAR TERM...WSS SHORT TERM...WSS LONG TERM...mlm AVIATION...WSS

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