Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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624 FXUS62 KRAH 210613 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 210 AM EDT Mon May 21 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 210 AM Monday... Primary drivers of weather today include a weak backdoor surface front moving in from the north and minor mid level shear axes shifting in from the south. The latest surface map shows a fairly uniform air mass across much of the Carolinas and Southeast, albeit with lingering instability over the eastern CWA, and a weak backdoor front stretches W-E across central VA. This front is expected to drop southward into N NC this morning before washing out and ultimately dissipating as it starts to shift back N tonight. This front is more of a temporary wind shift, with minimal change in low level thicknesses, so impacts should be little more than weak low level mass convergence over the N Piedmont this afternoon. But this resultant forcing in tandem with afternoon heating and subsequent destabilization (tempered a bit by considerable mid and high clouds across the region) should allow scattered afternoon convection to be focused over the N Piedmont and N/C Coastal Plain starting in the mid afternoon, perhaps dropping into the Sandhills, S Coastal Plain and S Piedmont late afternoon into early evening, although this will depend to a large degree on cold pool propagation. While moderate CAPE is expected over the N and E CWA, other forcing mechanisms will be absent or very weak, including the aforementioned surface frontal convergence and subtle mid level waves tracking northward through the area between the offshore-centered mid level anticyclone and low pressure over the FL panhandle. Latest model runs are favoring pretty good convective coverage along the frontal zone, and will retain the trend up to likely pops across the N/E with lower coverage in the SW. Storm intensity will be limited by the weak deep layer shear, although forecast soundings suggest elevated D-CAPE with potential for strong wind gusts, and high values of normalized CAPE favor high lightning activity. Expect highs in the low-mid 80s, with some upper 80s SW. Storms should decrease gradually in coverage and strength during the evening and into the overnight hours, although residual surface heat flux and high dewpoints necessitate keeping chance pops in through the night. Lows in the upper 60s to near 70 under mostly cloudy skies. -GIH
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&& .SHORT TERM / /...
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As of 330 PM Sunday... To be updated shortly.
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&& .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 /06Z MONDAY THROUGH FRIDAY/... As of 125 AM Monday... VFR conditions will dominate at central NC terminals through the next 24 hours, although there is a good chance of MVFR to IFR conditions 08z-12z this morning at FAY/RWI with a lower chance at RDU. Considerable mid level cloudiness based above 8 000 ft AGL is expected today through tonight, with scattered to periodically broken clouds based at 3 500 - 6 000 ft AGL this afternoon. Light winds and high humidity early this morning may induce development of stratocumulus based at 500-800 ft agl across the eastern sections in the hours before and around daybreak this morning. Scattered showers are possible near RDU/RWI 15z-18z, then scattered to numerous storms are possible 18z-00z later today at RDU/RWI/FAY, with a lower chance near INT/GSO. Shower/storm chances will decrease quickly after 00z. Looking beyond 06z Tue, VFR cigs/vsbys will dominate through Tue morning, with a slight chance of sub-VFR cigs 08z-12z. Another round of scattered showers/storms with local sub-VFR conditions is expected 18z-00z Tue. This pattern is expected to repeat through the week, with storm chances from mid afternoon through mid evening and low clouds or fog possible late each night through dawn. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...Hartfield SHORT TERM... LONG TERM...Franklin AVIATION...Hartfield

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