Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 241948 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 345 PM EDT Sun Sep 24 2017 .SYNOPSIS... High pressure centered over the Great Lakes and northern Mid Atlantic states will extend south into our region through Monday. Hurricane Maria is forecast to move north through the western Atlantic, paralleling the SE Coast through midweek. && .NEAR TERM /THROUGH TONIGHT/... As of 259 PM Sunday... Subsidence associated with the stacked anticyclone centered over the NE and Mid-Atlantic states will support dry and stables conditions across central NC. Under mostly clear/fair skies, lows tonight will once again fall into the lower to mid 60s. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... As of 259 PM Sunday... Deep layer ridging centered over NY will prevail across the region on Monday, before weakening/breaking-down Monday evening/night as Maria continues to move north-northwest, paralleling the Carolina Coast. Expect a gradual increase of high level cloudiness throughout the day as the outer outflow cirrus bands push west into the area, which should be sufficiently opaque along and east of I-95 to temper afternoon heating. Highs ranging from lower 80s in the east to mid/upper 80s SW. The pressure gradient between the high to our north and Maria will also begin to tighten, producing wind gusts in the mid to upper teens. Strengthening NELY low-level flow will advect some Atlantic maritime moisture in the form of low clouds/stratus into the eastern half of the forecast area Monday night. Owing to the increase in clouds/moisture, low temps Monday night will be a few degrees warmer than past recent nights. Lows in the mid to upper 60s. && .LONG TERM /Tuesday through Sunday/... As of 345 PM Sunday... Tue through Thu night: Hurricane Maria is expected to drift slowly northward off the NC coast Tue-Wed, before getting caught up in the westerlies and taking a turn NE and out to sea Thu. The official forecast track follows the op GFS more closely than the ECMWF, which tracks Maria`s center a bit closer to the NC and about 18 hrs slower than the GFS by Thu. Will hew more closely to the op GFS for sensible weather. Based on the latest NHC wind radii forecasts, we are very unlikely to see tropical storm force winds into our forecast area. However, momentum transfer noted on forecast soundings suggests that frequent gusts to 20-25 kts are likely in our eastern third, especially when Maria`s center makes its closest approach Wed. Skies Tue should trend to fair west, with streaks of thin high clouds streaming off the top of Maria northwestward over NC, with partly to mostly cloudy skies east where greater low level influx of Atlantic moisture should result in scattered to broken stratocu. As Maria tracks up to and north of the latitude through central NC, the backing of low level winds to be from a more northerly or northwesterly direction should help draw drier air back in, such that clouds should thin out Wed, and likely be primarily partly cloudy through Thu. Shower chances appear to be small, with models generally confining small chances of measurable precip to the east. Will continue with isolated shower pops Tue through early Thu, as far outer bands may work into the Coastal Plain at any time. Highs 80-86 Tue and 81-89 Wed, with narrow ridging aloft NW and then W of Maria and thicknesses 10-15 and 15-20 m above normal respectively. By Thu/Thu night, broad mid level troughing over much of NOAM (all but the far S and W) begins to dig over the Upper Midwest, pushing a moisture-starved cold front to the SE, over the NC mountains and through the state late Thu through Thu night. Expect highs of 83-90 Thu with thicknesses likely to be nearly 20 m above normal. Lows in the mid 60s to lower 70s Tue night and Wed night, slipping to the low-mid 60s post-front Thu night. Fri through Sun: The digging mid level trough shifts eastward over the weekend, while cool high pressure drifting from the Upper Midwest across the Great Lakes to the Northeast ridges down through NC. The GFS develops a baroclinic zone near the SE Coast, along which low pressure tracks. While this is far from certain to occur, given some disagreement in the models, will still leave in a low chance of showers over the SE, mainly late Sat through Sat night, still below climatology. Otherwise, expect fair to mostly sunny skies. Highs in the upper 70s to lower 80s Fri, then in the 70s Sat/Sun, making for a pleasant fall weekend. -GIH && .AVIATION /18Z SUNDAY THROUGH FRIDAY/ As of 115 PM Sunday... 24 Hour TAF Period: VFR conditions are generally expected to continue through the 24 hour TAF period as high pressure extends into the area from the north. A steady 3 to 5kt northerly breeze should preclude any widespread fog development overnight. Outlook: As Hurricane Maria moves northward through the western Atlantic near a latitude of the NC coast, eastern terminals could see some sub-VFR ceilings as early as Monday night/Tuesday morning with breezy northerly winds developing by Tuesday and lingering into Wednesday. Based on the latest NHC official track, precipitation and resultant aviation impacts will be minimal and confined to eastern terminals. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CBL NEAR TERM...CBL SHORT TERM...BSD LONG TERM...Hartfield AVIATION...CBL

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