Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 230651 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 251 AM EDT SAT JUL 23 2016 .Synopsis... An area of high pressure aloft will expand from the central U.S. across the mid-Atlantic states and Carolinas through early next week. This will bring a period of hot temperatures to central NC. && .Near Term /Overnight/... As of 720 pm Friday... Central NC lies on the eastern periphery of a deep upper level ridge (centered over the lower Midwest) and on the western periphery of an upper level trough stalled offshore the Southeast coast. Similar to yesterday, diurnal destabilization this afternoon has been strongest in the W/SW Piedmont (1000-2000 J/kg MLCAPE) and weakest (500-1000 J/kg MLCAPE) in eastern/coastal NC where subsidence prevails on the backside of the upper level trough stalled offshore. Small amplitude disturbances /DPVA/ rounding the NE periphery of the 300 mb ridge over the central Appalachians could track into western NC this eve/tonight, however, the `sphere of influence` of such disturbances should remain west of central NC as they track S/SSW along the eastern periphery of the H3 ridge. As a result, forcing for ascent this evening will be confined to shallow convergence attendant a weak Piedmont trough and convective outflow. With the above in mind, expect scattered convection to largely remain confined along/west of Highway 1 and to gradually weaken/dissipate within a few hours after the loss of heating/insolation. Expect lows generally in the lower 70s, though a few rural/low-lying areas in the N/NW Piedmont may fall as low as 68-70F. -Vincent && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
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As of 345 PM Friday... The environment on Saturday should be similar to today, although PW values are expected to rise steadily, with thicknesses continuing to climb. We`ll also be on the anticyclonic side of MCVs dropping southward through the southern Appalachians, with no other dynamic forcing mechanisms evident. So we`ll be relying on purely thermodynamic lift, it appears, focused on differential heating in the higher terrain as well as subtle boundaries, a few of which may be leftover from the current convection over western NC. Will expand the low shower/storm chances a bit from today`s pops, but still expect coverage and upscale growth to be limited by warm and somewhat dry mid levels. Thicknesses and new guidance indicate highs of 94-98, and with dewpoints dropping no further than around 70 over much of the area, heat index values should peak in the 99-104 range for a couple of hours. This is below advisory criteria, so will stick with a mention in the HWO for now, but this will certainly be revisited tonight. Lows Sat night in the low-mid 70s, not allowing much recovery from the heat stress. -GIH
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&& .LONG TERM /TUESDAY THROUGH FRIDAY/...
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As of 245 AM Saturday... Additional s/w energy is expected to track across Southern/Southeastern Canada and the Great Lakes and Northeast U.S. next week, which will allow a weak cold front to approach the region (likely stalling to the north of the area though). This will allow the mid level ridge to dampen across our region early next week and relocated to the south and southeast of central NC. This should place central NC on the southern fridge off potential disturbances tracking atop/around the ridge, which should lead to a better chance of mostly diurnal scattered showers and storms each afternoon/evening. Given the predictability of such hard to time features this far out in the forecast, will go with around 30-35 percent chance for showers and storms each day (generally climo). This additional associated cloud cover is expected to lead to temps a bit cooler, though highs are still expected to at least be in the lower to mid 90s.
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&& .Aviation /06Z Saturday through Wednesday/... As of 140 AM Saturday... VFR conditions expected to prevail across central NC through Monday as an area of high pressure aloft builds over the region. While isolated thunderstorms will be possible each late afternoon-early evening through Monday, probability of convection affecting a specific TAF site is too low to mention in the terminal forecast at this time. Patchy MVFR fog will be possible early each morning, primarily between the hours of 10Z-12Z. While VFR conditions will likely dominate through Wednesday, there will be periods of MVFR conditions associated with either early morning fog, or late afternoon/early evening convection. && .Climate... Record high temperatures and the year in which the record was most recently set at Raleigh, Greensboro, and Fayetteville. Sat Jul 23 Sun Jul 24 Mon Jul 25 RDU 105/1952 101/2011 102/2010 GSO 99/1952 99/1914 101/1914 FAY 103/2011 105/1952 103/1914 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...Vincent SHORT TERM...Hartfield LONG TERM...BSD AVIATION...Hartfield/mlm CLIMATE...BLAES

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