Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 280112 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 840 PM EDT Thu Apr 27 2017 .SYNOPSIS... A cold front will over the Mountains this evening will drift into the central Piedmont overnight, then dissipate. A strong high pressure will build off the southeast coast Friday and linger into Saturday. A moist southerly return flow on the western periphery of the strengthening Bermuda high will prevail Friday through the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 748 PM Thursday... Central and eastern parts of our region, essentially east of the Triad region eastward are in the clear for now, and expected to be so for the evening. The air mass continued to be rather stable and not favorable for convective development. To the west, as previously mentioned the cold front was drifting into the Mountains. Conditions were more unstable and favorable for convective showers/iso thunderstorms in this region. However, the most unstable air did reside along the boundary over the Mountains and the forecast is for the boundary layer east of the mountains to cool and stabilize further as the the evening unfolds. Therefore, the scattered showers and isolated thunderstorms tracking NE over the Mountains, Foothills, and western Piedmont should weaken with time this evening. We will maintain the highest POP (likely) over the Winston- Salem area, with lower POP (chance of shower) from Greensboro and Lexington eastward to Burlington for the next few hours. Otherwise, no POP in the east. Then later tonight and early in the morning, the cold front will slowly advance east toward the central Piedmont. As this occurs, the latest HRRR and other hi-res models suggest only a low chance of showers associated with the front. Otherwise, simply a partly cloudy evening and overnight with warm temperatures. Lows should be in the mid to upper 60s (or a good 15-18 degrees above normal). && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 330 PM Thursday... In the wake of the upper wave lifting through the Great Lakes, the sub-tropical ridge will expand across the Southeast Friday into the weekend. Strong heating, with thicknesses approaching 1420m on Saturday, will leave to highs in the upper 80s Friday and upper 80s/low 90s on Saturday. A strong cap will limit any convection to the seabreeze on Friday, where the cap will be weaker owing to strong heating, but dry air will ultimately limit the coverage storms. Lows Friday night in the mid to upper 60s. Strong instability will develop on Saturday as an elevated mixed layer advectS across the region, deflect to the north a bit by the mid-level ridge. MLCAPE as high as 3000 J/KG is forecast by both the NAM and GFS. The threat of severe storms will be conditions upon convective development, which will be hindered by dry mid-level air (which will also support 1000 J/KG of DCAPE) and the lack of a focus, other than the terrain induced differential heating. Models do indicate a shallow tropopause disturbance/jet emerging off the GOMEX saturday, which given the strong instability could be enough to offer some forcing. However, confidence is low at this point. Lows Sat night will be in the upper 60s. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 330 PM EDT Thursday... The subtropical ridge will retreat a bit on Sunday and especially Monday as an upper low lifts of the southern Plains. the associated cold front and convection are forecast to move into central NC Monday night, later than in prior forecasts, with limited instability and and forcing as it moves east. The front will also serve to knock temps back to more seasonal values, with highs in the 70s and lows in the 50s for midweek. Some uncertainty develops midweek, as the front is forecast to stall over the region and may be the focus for some unsettled weather as another shortwave or two swing through the longwave trough generally over the eastern US. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... As of 840 PM Thursday... 24 Hour TAF Period: A cold front will slowly move into the area this evening/tonight, while dissipating. KGSO/KINT stand the best chance of see sub-VFR conditions and thunderstorms from 00-04Z this evening. Further east, from 02-08Z VFR/MVFR conditions in showers will be possible. IFR/MVFR cigs will be possible early Friday morning through around mid/late morning-early afternoon as well. VFR conditions are expected to return Friday afternoon as strong high pressure aloft expands over the region. Outlook: A very summer-like pattern through the weekend with sub-VFR stratus possible during the early morning hours, scattering out by 15Z, and isolated afternoon convection being focused mainly around GSO/INT. Otherwise, expect the best overall potential for convection Monday evening/night in assoc/w a cold front /squall line/ progged to track eastward through the Carolinas. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Badgett NEAR TERM...Badgett SHORT TERM...SMITH LONG TERM...SMITH AVIATION...BSD/SMITH

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