Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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653 FXUS62 KRAH 261958 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 358 PM EDT Fri May 26 2017 .SYNOPSIS... A weak trough will extend down through western and central North Carolina. An upper level disturbance will cross the region late Saturday through Saturday night, followed by another disturbance Sunday afternoon. && .NEAR TERM /TONIGHT/... As of 350 PM Friday... Heights will continue to rise this evening as upper ridging builds into the area then flattens tonight. Pressure gradient will continue to relax with the development of a lee side trough across western NC. The MCV and associated over IL this afternoon will progress east into northern Mid-Atlantic States overnight. Thin high level debris cloudiness associated with this convection may overspread central NC after midnight, with little sensible impact on lows. Lows in the lower 60s. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... As of 350 PM Friday... Low amplitude shortwave disturbances riding atop the flat subtropical ridge in place across the southern U.S. will set the stage for scattered upstream convection to move into the area within a west-southwesterly WAA belt spreading east into the southern Appalachians late tonight/early tomorrow morning and then into central NC on Saturday. The convection should align closely to a wavy west-east frontal zone that will initially push east into VA during the afternoon, and then gradually sag south into central NC during the evening and overnight, likely aided by the expected convective and associated outflow. While an EML plume advecting into the area may help to bolster destabilization across the area, it may also serve to limit convective coverage especially south of US 1. Will keep a good/high chance across the far north with only slight chance pops across the south, with a decrease in pops with cooling after sunset. A strong mid-level wind field will result in favorable deep layer shear of 30 to 35 kts, along with moderate instability to support a cluster or two of severe storms capable of producing large hail and damaging straight-line winds, mainly along and north of HWY 64. Warming H8 temperatures to 15 C tomorrow(+ 5C from Friday) with a corresponding 20 meter rise in low-level thicknesses to 1420 meters will support a quick return to above normal temperatures. Highs in the mid to upper 80s north to lower 90s south. Lows tomorrow night in the mid to upper 60s with some patchy fog possible where any heavy rain falls. && .LONG TERM /Sunday through Friday/... As of 300 PM Friday... A short wave trough over the TN valley Sunday morning will move east and across the Carolinas by late day. Scattered showers/tstms are expected along and ahead of it, developing over the mountains around mid-day and moving east across our cwa during the late afternoon into early evening. With 2000+ J/kg cape and 40+ kt of deep layer shear forecast in the models, the environment would appear to support at least isolated strong to severe tstms. Given the position of an old boundary along and north of hwy 64, look for the best chance for such activity to be across the northern half of our CWA. Short wave ridging behind the aforementioned short wave will provide a break in the weather Sunday night into Monday morning, but the next short wave moving through the longwave trough centered over the Great Lakes will move across the Carolinas late day Monday into Monday night, helping to push a weakening cold front across our area. This system will provide the next chance for showers and tstms Monday afternoon through Monday night. For the rest of the long term period, will keep pops near or above climo each day as the aforementioned cold front will stall across the region and a series of mid level short waves embedded in the broad cyclonic flow move across the region. Above normal temps forecast through the period. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... As of 141 PM Friday... Strong subsidence, behind the departing upper level trough will result in VFR conditions through the 24 hour TAF period. Breezy west- swly winds will gradually subside as pressure gradient relaxes through the afternoon/early evening, with flow becoming SWLY with the development of pre-frontal surface trough in the lee of the mountains. Outlook: A series of upper level disturbances along a back-door cold front forecast to sag south into the area over the weekend will support a chance of showers and storms late Saturday afternoon/evening, and again on Sunday afternoon and evening owing to the presence of a moist and unstable airmass. With the front stalled across the area, the threat of mainly afternoon/evening showers and storms will continue on Monday, and again on Tuesday with the approach of another cold front from the west. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...CBL SHORT TERM...CBL LONG TERM...np AVIATION...CBL

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