Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 290535 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 135 AM EDT Sun May 29 2016 .SYNOPSIS...
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Tropical Storm Bonnie will approach the South Carolina coast this morning, and then track slowly northeastward along the South Carolina and North Carolina coastline through the middle of the week.
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&& .NEAR TERM /Through Tonight/... As of 841 PM Saturday... The latest information from the NHC indicated that TS Bonnie had stalled in the last few hours. It is expected to resume the NW movement but less than 10kt this evening as it tracks toward the southern SC coast. There continued to be an impressive plume of deep moisture advecting NW to the east of the center of circulation of Bonnie. At the surface, a surface trough or wind shift line had advanced westward into the Piedmont from the Coastal Plain at mid- evening. Dew points jump into the mid to upper 60s from the upper 50s as the trough moves passes and winds become more easterly off the Atlantic. An initial rain band was rotating NW toward the SE NC coastal region this evening. It appears that it will be late evening before some of this band moves into our southern Coastal Plain. We will ramp up POP in the SE to account for this activity and additional rain later on. Conversely, we will cut POP back for the NW-N zones to a slight chance through 06Z, then as the rain/showers develop and spread NW-W increase POP between 06Z-12Z throughout the region. It appears a surface trough will set up over the region later tonight into Sunday. It should be along this convergence axis that rain/showers become widespread later tonight and Sunday. With dew points rising and skies becoming cloudy, expect lows 65-70 SE and lower to mid 60s NW. && .SHORT TERM /Sunday through Sunday night/... As of 200 PM Saturday... TD#2 is expected to become a low-end tropical storm prior to landfall (or closest approach to the SC coast) around 12Z Sunday morning. The precise evolution of this system (the track in particular) will heavily influence the location/amount of rain that falls across central NC Sunday into Sunday night, as demonstrated by the wide variety of solutions obtained from various convection allowing models. As a result, the location(s) or area(s) that will receive the heaviest rainfall remain difficult to pin-down at this time. Based on the official NHC guidance, one would expect the axis of heaviest rain to become oriented N-S or NNE-SSW in vicinity of Highway 1 or I-95. Locally heavy rainfall amounts of 1-3" will be possible in this area. High temps will depend primarily upon cloud cover and precipitation, which should be pervasive over much of central NC. As such, will indicate highs in the mid/upper 70s, though lower 80s will be possible if/where there are breaks in cloud cover. Expect lows in the mid/upper 60s (possibly near 70F) Sunday night with a tropical airmass in place, southeasterly flow off the Atlantic, lingering cloud cover, and showers. Hazardous Weather: A localized potential for flash flooding will be present Sun/Sun night, primarily in urban areas. Given the anticipated location of TD#2 (expected to stall in southern SC during the day Sun), the best low/mid-level shear (mini-supercell/ tropical tornado potential) is expected to remain south of central NC, along and near the coast from Charleston SC north to Wilmington, NC. -Vincent && .LONG TERM /Monday Through Saturday/... As of 310 pM Saturday... Monday through Wednesday: The low associated with tropical depression two will be captured in a weakness or trough in the upper- level pattern over the southeast U.S. and a 590m ridge over the western Atlantic. This will result in a very slow east to northeast drift of the surface low as the ridge over the Atlantic weakens. The best precipitation chances during the period should be focused across central the eastern half of NC and in our forecast area across the coastal Plain/Sandhills and the eastern Piedmont. This is given the northward advection of deep layer moisture on the backside of the offshore ridge and to the east of the trough axis combined with some modest forcing for ascent east of the trough and low-level convergence resulting from the tropical circulation and frictional convergence in the coastal region. The greatest rain chances during the period will likely be on Monday east of U.S. route 1 where rain coverage and amounts will be greatest. Rain chances decrease somewhat on Tuesday and Wednesday. Rainfall amounts will be rather localized with slow moving bands and clusters of showers/storms driving precipitation amounts. Average amounts through the period will range around an inch to an inch and half from I-95 east, a half inch to an inch between U.S. 1 and I-95 and a half inch or so west of U.S. 1. While these amounts aren`tterribly impressive, we fully expect localized higher amounts during the period. Highs during the period will generally range in the lower 80s on Monday and the lower to mid 80s on Tuesday and Wednesday with morning lows in the mid to upper 60s. Thursday through Saturday: A slow moving trough pushes east across the plains on Thursday and extends from the eastern Great Lakes to the northern Gulf of Mexico on Friday and Saturday. The eastern progression of the trough slows as heights rise off the Southeast coast and the remnants of TD two eventually dissipate off the Northeast coast. The developing southwesterly flow ahead of the approaching upper trough leads to another period of moisture transport with increasing instability. After a modest decrease precipitation chances on Thursday in between systems and with a minimum which should result in a period of unsettled weather for Friday into Saturday with showers and thunderstorms. highs will mainly range in the lower to mid 80s with lows in the 60s. -blaes && .AVIATION /06Z Sunday through Thursday/...
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As of 135 AM Sunday... Details are tough to pin down but the most likely scenario consists of current VFR conditions at all sites slow deteriorating to MVFR later this morning, and wavering between MVFR and VFR through much of today. As low level moisture increases further, pockets of MVFR vsbys in fog are expected areawide between 07z and 12z this morning. The center of Tropical Storm Bonnie, currently located off the SE coast ESE of SAV, is expected to push slowly to the NW before stalling out near the central SC coast through much of today. A surge of Atlantic moisture to the NE of Bonnie is expected to bring a band of showers toward the NNW through central NC from mid morning through early afternoon, followed by patchier and more widely scattered showers and perhaps a storm or two during the mid to late afternoon, with the best chance of storms at RDU/FAY/RWI. Within this first band of steady showers, cigs and vsbys should drop to MVFR with cigs potentially IFR at times. Once this main band shifts northward by early afternoon, conditions should vary between MVFR and VFR through early evening. MVFR to IFR fog and stratus are apt to redevelop after sunset, especially at INT/GSO/RDU, with scattered showers persisting areawide. Looking beyond 06z Mon: Unsettled weather will persist with periods of sub-VFR conditions expected through Mon, including a good chance of showers and storms Mon afternoon. IFR fog/stratus likely to redevelop for Mon night / Tue morning. Numerous sub-VFR showers and storms expected Tue afternoon at RDU/RWI/FAY, with less coverage and mostly VFR conditions at INT/GSO. Chances for sub-VFR showers diminish by Wed/Thu as the TS Bonnie circulation and associated upper level disturbance finally shifts NE away from the forecast area. -GIH
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Badgett SHORT TERM...Vincent LONG TERM...blaes AVIATION...Hartfield is the U.S. government's official web portal to all federal, state and local government web resources and services.