Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 281757 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 157 PM EDT Sun May 28 2017 .SYNOPSIS... A series of upper level disturbances will track east across the Carolinas this afternoon through Monday evening. && .NEAR TERM /THROUGH TONIGHT/...
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As of 200 PM EDT Sunday... The EML in place over the Carolinas the past few days has been modified and suppressed southward by numerous rounds of convection over the past 24 hours, with H7-H5 lapse rates ranging from ~5.5c/km near the VA border to 6.0-6.5C/km near the SC border. Diurnal destabilization this afternoon is expected to range from marginal (~500 J/kg MLCAPE) near the VA border to moderate (1500-2500 J/kg MLCAPE) near the SC border where the strongest insolation and richest low-level moisture will be juxtaposed with mid-level lapse rates on the order of 6.0-6.5c/km. With numerous MCVs upstream of the Carolinas, significant uncertainty persists with regard to the timing/coverage of convection this aft/eve. Convection allowing models such as the 12Z HRRR and NAM NEST suggest scattered convection will develop over western NC around ~21Z and propagate east across central NC through ~03Z this evening, presumably in association with one of several MCVs expected to track across portions of the Carolinas. Moderate destabilization, effective shear on the order of 40-50 knots, straight hodographs, and relatively steep mid-level lapse rates across the SW Piedmont/Sandhills suggest the primary mode of convection (should it develop) will be splitting supercells with an attendant threat for large hail (1.00-1.75"). Damaging winds cannot be ruled out, however, the environment in place across central NC today is significantly less supportive than in previous days (DCAPE 500-750 J/kg (primarily near the SC border) this afternoon. Diurnal destabilization will be weakest north of Hwy 64, particularly in the NE Coastal Plain where weak mid-level lapse rates will be juxtaposed with a cooler airmass in vicinity of a stalled front near the VA border. With the above in mind, a conditional potential for splitting supercells will exist later this aft/eve, with a primary threat of severe hail (1.00-1.75"). Expect highs this afternoon to range from the lower 90s near the SC border to the lower 80s near the VA border in the Northern Piedmont and NE Coastal Plain. Lows tonight should range from the mid/upper 60s near the VA border to lower 70s near the SC border. -Vincent
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&& .SHORT TERM /MONDAY AND MONDAY NIGHT/... As of 230 AM EDT Sunday... Monday and Monday night: A marginal to slight risk of severe storms expected again Monday afternoon and evening, mainly in the eastern counties. A cold front is forecast to push into the region Monday and Monday evening. Timing of the front is in question, but the slower models may be best. However, any convective outflows may be the main thing to watch for additional strong to locally severe storms Monday afternoon and evening. Both the GFS and EC are in reasonable agreement with the placement of the forecast highest instability and suggest that MLCAPE values could again reach the 1500 to 2000 J/kg range, mainly over the Coastal Plain, where heating may be best. Highs should reach the mid to upper 80s with dew points in the upper 60s. This area should also be in the region of strongest shear with 35-40kt of WSW flow expected (0-6 km). The main threats should be large hail and damaging wind gusts. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 345 AM EDT Sunday... A deep mid/upper level trough is expected across the eastern half of the country next week, with the associated deep mid/upper low expected to slowly wobble eastward across SE Canada/NE U.S. An associated weak cold front will stall/dissipate across eastern portions of the area on Tuesday, with another weak cold front settling south and eastward across the area on Wednesday. This should result in a continued threat of showers and storms across mainly south and eastern portions of the area on Tuesday and areawide Wednesday. However, will keep pops in the low chance/slight chance categories, given differences in model guidance timing of hard to track low amplitude disturbance this far out in the forecast. High temps will generally be in the 80s during this time frame, with lows in the 60s. Surface high pressure will move across the area on Thursday, resulting in generally a dry day, as mid level flow becomes westerly. Mainly diurnal chances of showers and storms are expected on Friday and Saturday as surface high pressure shifts offshore. High temps late week into the weekend are generally expected to be in the 80s and lows in the 60s, near seasonal norms. && .AVIATION /18Z SUNDAY THROUGH THURSDAY/...
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As of 200 PM EDT Sunday... 24-HR TAF Period: VFR conditions are generally expected to prevail through the TAF period. Isolated/scattered convection will be possible late this afternoon and evening at all terminals, however, confidence in coverage/timing will preclude mention thereof with the 18Z TAF issuance. Expect W/SW winds at ~10 knots with occasional gusts to 15-20 knots. Looking ahead: Aside from a potential for isolated/scattered diurnal convection during the afternoon/evening hours each day, VFR conditions are expected to prevail through mid-week. -Vincent
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Vincent NEAR TERM...Vincent SHORT TERM...Badgett LONG TERM...BSD AVIATION..Vincent is the U.S. government's official web portal to all federal, state and local government web resources and services.