Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 251901 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 301 PM EDT Wed May 25 2016 .SYNOPSIS...Surface high pressure will extend into the region through Friday. Meanwhile, a storm system will develop over the sub-tropical Atlantic and drift toward the Southeast coast through the weekend. && .NEAR TERM /through tonight/... As of 1045 AM Wednesday... Little change/adjusted required to the near term forecast. Anti-cyclonic flow, a result of a mid/upper level ridge over the Deep South and TN Valley, will maintain warm and dry conditions today across central NC. While the lower layers of the atmosphere will become slightly unstable this afternoon, a subsidence inversion between 750-650mb will act as a cap, inhibiting convective development. Low level thicknesses this afternoon projected to reach the 1410- 1415m range, a solid 15m warmer than normal. This suggest max temps in the mid-upper 80s, in line with current forecast. -WSS Conditions will again be good for radiational cooling tonight, the exception being the western Piedmont where patchy mid/high clouds associated with upstream convection may become mostly cloudy for a period late in the night. Lows in the upper 50s and lower 60s. -BLS && .SHORT TERM /Thursday through Thursday Night/...
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As of 350 AM Wednesday... While high pressure, both at the surface and aloft, will remain over the region on Thursday, increasing PW to near 1.5" and a little better instability (500-1000 J/KG) will support a better chance of convection, mainly in the western Piedmont from storms moving off the higher terrain. The environment won`t be supportive of organized convection, so the threat of any strong storms is low and will be limited to enhancement from steepening low-level lapse rates. highs again in the upper 80s. The GFS appears much too aggressive with convection continuing into Thursday night given that the ridge will begin to restrengthen in response to the subtropical system developing over the northern Caribbean. Instead, skies should end up mostly clear and lows will dip back into the low/mid 60s. Friday and Friday night: Coming shortly.
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&& .LONG TERM /Saturday through Wednesday/...
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As of 300 PM Wednesday... The general overall pattern for the weekend and into early next week will be characterized aloft by a ridge over the SE U.S. and a trough over the Midwest. A low pressure system in the mid to upper levels will develop off the FL coast beneath the ridge. At the surface, the high that was ridging westward into the Carolinas will be pushed northward and largely out of the region by the developing low as it moves north-northwestward along the FL coast. The aforementioned low pressure system will develop off the FL coast Friday night into Saturday and could develop tropical or sub- tropical characteristics as it moves northwestward. Though there are still plenty of model differences on the evolution of this low, there is fairly good model agreement and thus high confidence that it will develop. The general track is expected to take it NW toward the SE U.S. coast on Saturday resulting in an increase in moisture, clouds, and chances for convection through the day and into the overnight hours. Beyond Saturday, the low could remain near the SC/GA coast through the remainder of the period. The exact coverage, location, and timing of convection is dependent on how the low evolves. However, the convection is expected to be largely diurnal in nature, with the highest chances in the aft/eve and a lull overnight. Rainfall amounts through the weekend and early next week will depend on the path of the low and given the uncertainty of that, will hold off speculation of totals for now. Temperatures through the period: with the increasing clouds and chances for rainfall, expect highs to decrease from the mid 80s on Saturday, to upper 70s to low 80s Sunday through Wednesday, with the potential for some mid 80s to creep back into the SW by Tuesday. Overnight lows will remain fairly steady in the mid to upper 60s.
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&& .AVIATION /18Z Wednesday through Memorial Day/... As of 110 PM Wednesday... An area of high pressure at the surface and aloft will maintain VFR conditions across central NC through Thursday night. The exception will be a slight threat for isolated afternoon-early evening convection on Thursday, mainly over the western Piedmont. Where the isolated convection occurs, expect MVFR ceilings and visibility as well as gusty sfc winds. Aviation conditions varying between VFR and MVFR will occur Friday and Saturday, mainly due to early morning fog and/or low stratus, and isolated-scattered afternoon through early evening convection. The probability for adverse aviation conditions will increase Sunday and Memorial Day as an area of low pressure off the southeast U.S. coast spreads deep moisture into our region resulting in sub_VFR ceilings and an increasing threat for scattered convection. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...BLS NEAR TERM...WSS/BLS SHORT TERM...BLS LONG TERM...KC AVIATION...WSS

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