Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 280712 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 312 AM EDT Fri Apr 27 2017 .SYNOPSIS...
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A warm moist southerly return flow will prevail through the weekend as an upper level ridge strengthens offshore the Southeast coast.
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&& .NEAR TERM /Today and Tonight/...
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As of 300 AM EDT Friday... Extreme destabilization (3000-3500 J/Kg MLCAPE) is expected today as rich low-level moisture advects poleward beneath a modified elevated mixed layer /steep mid-level lapse rates/ in the presence of unimpeded insolation. Despite atypically favorable thermodynamics, a strong cap at the base of the EML combined with the absence of any discernible forcing is expected to preclude convective development. Convective inhibition will be greatest over western portions of the state where afternoon temps will top out in the mid 80s (versus ~90F in eastern NC). Unless a well-timed shortwave/MCV in SW flow aloft progresses across western NC or upstream convection propagates downstream into western NC (neither are likely based on the latest mesoanalysis/observational data and short term model guidance), convective development is highly unlikely. Erosion of CINH will be greatest in eastern NC this afternoon where weak low-level convergence will be present in assoc/w the seabreeze (assuming it penetrates inland). However, such weak/shallow forcing is unlikely to break the cap nor sustain updrafts in the presence of such a dry mid-level airmass. It is fortunate that deep convection is unlikely to develop considering that thermodynamic/kinematic profiles would strongly support robust supercells capable of producing destructive hail/microbursts. With a moist low-level return flow and expected development of stratus, expect overnight lows in the mid 60s to lower 70s. -Vincent
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&& .SHORT TERM /Saturday and Saturday Night/...
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As of 300 AM EDT Friday... Thermodynamic conditions on Saturday will be very similar to today, though kinematic profiles are progged to be weaker. Regardless, a strong cap and lack of forcing is once again expected to preclude convective development. Expect above normal highs in the lower 90s with lows Sat night in the mid/upper 60s to lower 70s. -Vincent
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&& .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 /06Z Friday through Tuesday/...
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As of 200 AM EDT Friday... 24 Hour TAF Period: MVFR/IFR fog has already (06Z) developed at the INT/GSO terminals in assoc/w calm winds and decreasing cloud cover (5 KFT ceilings). Expect conditions at INT/GSO to worsen through sunrise as IFR/LIFR fog/ceilings develop. Eastern terminals should also see sub-VFR visbys/ceilings develop prior to sunrise as cloud cover decreases from west-east. Conditions will gradually improve to VFR late this morning in association with diurnal heating/mixing. VFR conditions are expected to prevail through midnight, with SCT/BKN diurnal Cu based at 3-4 KFT this afternoon. IFR/LIFR stratus is anticipated to develop by the end of the TAF period at all terminals, between midnight and sunrise Sat. Looking Ahead: VFR conditions are expected to prevail through the weekend, aside from early morning stratus (IFR/LIFR ceilings). Convection appears unlikely until a cold front progresses eastward into the Carolinas late Monday into Monday night. -Vincent
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Vincent NEAR TERM...Vincent SHORT TERM...Vincent LONG TERM...SMITH AVIATION...Vincent

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