Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 202256 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 655 PM EDT Tue Jun 20 2017 .SYNOPSIS...
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A stalled frontal zone over the region will gradually dissipate tonight. A low-level southwesterly flow will prevail through the remainder of the week.
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&& .NEAR TERM /Tonight/...
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As of 655 PM EDT Tuesday... Some changes made to the PoP tonight, mainly to increase to likely across the southeast two-thirds of the region. This lead to a minor adjustment upward in the rainfall amounts tonight along and east of highway 1. A s/w in the northern stream crossing the lower Great Lakes into the northern Mid-Atlantic will induce a weak shear axis, currently aligned from eastern NC into central GA, to drift northwestward tonight. This will shift the plume of moisture crossing the eastern half of SC and southeastern NC into the se half of central NC later this evening and into the overnight. A series of perturbations aloft interacting with this available moisture should cause scattered- numerous showers to form, with the most persistent showers to occur primarily south and east of Raleigh. Expect rainfall amounts tonight between two-tenths to a half inch with locally greater amounts near an inch where heavier showers repeat across the same location. This threat for locally heavy rain appears greatest along and east of a Wilson-Fayetteville line. Widespread overcast along with the showers will result in a fairly uniform min temperature field. Overnight temperatures primarily in the upper 60s.
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&& .SHORT TERM /Wednesday and Wednesday Night/... As of 1200 PM EDT Tuesday... The aforementioned frontal zone is expected to wash out tonight as richer low-level moisture returns to central NC via a S/SW return flow. Central NC will remain at the southern periphery of the westerlies in broad cyclonic flow aloft on Wed, however, flow aloft will veer from the SW/WSW to WNW during the day, advecting a drier mid-level airmass into the region during the afternoon and evening. With the above in mind, expect a potential for ongoing convection Wed morning, however, expect activity to wane from W-E during the afternoon as a drier airmass aloft advects into the region. Expect highs in the lower/mid 80s, lows Wed night in the mid/upper 60s to lower 70s, warmest far S/SE. -Vincent && .LONG TERM /Thursday through Tuesday/... As of 320 PM EDT Tuesday... Deep southerly-southwesterly flow between newly formed T.S. Cindy that`s currently over the Gulf of Mexico and the subtropical ridge over the western Atlantic, will channel a plume of tropical moisture(PWATS ~2.25")northward into the region as early as Thursday night and could linger over the area until a cold frontal passage late Sunday and into Monday. Model spread remains high, specifically WRT to the timing heavy rain chances and qpf amounts across the Carolinas, largely due to the uncertainty in the interaction/phasing of the northern stream shortwave and the remnant circulation center associated with T.S. Cindy. Given the low confidence, will refrain from getting to specific in forecast details. While we do not expect continuous heavy rain through that period, conditions will be favorable for episodic heavy rain through the period, perhaps initially from the initial surge of tropical moisture and embedded upper disturbances (potentially convectively induced) ejecting NEWD across the region, and then followed by a second or quite possibly even third heavy rain event associated with Cindy`s remnant circulation center/energy aloft and then if separate, with the actual cold frontal passage. Early indicators suggest that central NC could see widespread heavy rainfall amounts of 2 to 4 inches from Thursday night through early next week. Rainfall totals over the past 5 to 7 days are already at 400 to 600 percent of normal across much of the area. Numerous creeks/small streams as well as main stem rivers are running high. Thus, any additional heavy rainfall over the next 5 days will result in prime conditions for both Flash and River flooding. A flood watch may will likely be needed, once better forecast confidence is reached. Highs will be highly dependent on rain chances through the period, ranging from mid 80s to lower 90s. Warm overnight lows in the upper 60s to lower/mid 70s. Cooler drier conditions should follow in the wake of the cold front on Tuesday. && .AVIATION /18Z Tuesday through Sunday/... As of 1200 PM EDT Tuesday... Light/variable winds and VFR conditions are expected to prevail through at least 21Z at the RDU terminal and 00Z at the INT/GSO terminals, on the northern periphery of a front stalled across portions of SC and southeast NC. Periodic sub-VFR ceilings/visbys associated with elevated convection on the northern periphery of the stalled front can be expected at the FAY/RWI terminals through the afternoon. Ceilings are expected to deteriorate to IFR and perhaps LIFR everywhere between 00-06Z as low-level flow veers to the south, pushing the frontal zone slowly N/NW as a warm front. Looking Ahead: Diurnal convection and early morning stratus will be possible each day Wed-Sat. Otherwise, VFR conditions will prevail. More widespread precipitation /sub-VFR conditions/ will be possible late this weekend, depending on the track/timing of Potential Tropical Cyclone 3 (currently in the GOMEX). -Vincent && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Vincent NEAR TERM...WSS SHORT TERM...Vincent LONG TERM...CBL AVIATION...Vincent

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