Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 220152 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 950 PM EDT THU JUL 21 2016 .SYNOPSIS... Surface high pressure will over the mid-Atlantic states will move offshore tonight. A strong high pressure ridge will expand from the central U.S. across the Carolinas over the weekend, bringing hot and humid conditions. && .NEAR TERM /THROUGH TONIGHT/... As of 950 PM Thursday... Only an isolated shower/thunderstorm was located over Moore County at mid-evening, with mostly clear, warm and humid conditions elsewhere. There are essentially no significant triggers noted for anything more than an isolated shower or storm through a couple of hours of midnight confined to the western Piedmont. Otherwise, mostly clear skies will continue overnight. Dew points did mix out into the 60s this afternoon, but have since increased into the 70s in the east and upper 60s in the NW. The return SE flow is responsible for the increase which will the a mainstay with the increase in heat as well over the next few days. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... As of 330 PM Thursday... Another fairly quiet day is expected, but with gradually building heat, and uncertainty regarding the fate of the MCV leftover from the complex now dropping through the Great Lakes. Models are not doing well handling the timing/movement of this MCS (too slow), thus their reliability is questionable. But using the timing of the SREF mean and steering flow would suggest that this could venture into the southern Appalachians by tomorrow, likely working with differential heating in the higher terrain and weak mass convergence along a lee trough to spawn scattered afternoon convection mostly to our west, although some of this could certainly spill into our far western Piedmont. But overall, the gradually rising warmth and dry air in the mid levels will limit the CAPE potential with continued poor mid level lapse rates. And the PW, while improving, should mean greatly reduce coverage. Will have isolated showers and storms over the NW Piedmont in the afternoon, trailing back off in the early evening as we lose any instability. Rising thicknesses will equate to highs in the lower 90s, even given the potential for some convective debris cloudiness early in the day, and this combined with dewpoints in the lower 70s and minimal reduction with mixing will generate heat index values in the mid to upper 90s -- a prelude to the more intense heat over the weekend. Lows in the lower to mid 70s Fri night with light fog possible. -GIH && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 240 PM Thursday... To begin the long term period, the strong upper ridge that provided multiple days of intense heat across the Central Plains will dampen some and start to spread east. As it does, heights will rise over central NC through the weekend. As such, max low level thickness values are progged to top out in the low to mid 1440s on Saturday (slightly lower than previous runs) and the mid to upper 1440s on Sunday. This combined with mostly dry conditions and temps not cooling off much as night, temps will be able to rise well into the mid 90s and even the upper 90s by Sunday. This combined with a moist air mass may necessitate the issuance of a heat advisory, most likely across at least the eastern half of the forecast area, where heat index values will approach or exceed 105 degrees. With regards to precip chances, overall they will stay rather low through the weekend, but will not be zero as there will be a persistent Piedmont trough that could be a focus for convective development, as well as any weak disturbances that move through aloft. The aforementioned ridge will dampen and shift even more over our region into early next week and eventually offshore, after another rather warm day on Monday. Also, a shortwave trough is progged to cross the Great Lakes Monday into Tuesday. This will propel a cold front towards the region Tuesday into Wednesday, but as can be expected this time of the year, there is disagreement with just how far south it will make it. Regardless, with us gradually losing the influence of the upper ridge and with a cold front in the vicinity, precip chances will start to increase, at least back to the normal diurnal range. The increased cloud cover and precip chances should allow temps to "cool" back to the lower 90s, especially Tuesday through Thursday. && .AVIATION /00Z Friday through Tuesday/... As of 815 PM Thursday... 24-hr TAF Period: Isolated convection in the Western Piedmont (Randolph/Davidson counties) is expected to remain south of the INT/GSO terminals prior to dissipating several hours after sunset this evening. VFR conditions and light/variable winds are expected to prevail through the TAF period as central NC lies on the western periphery of a trough stalled offshore the Southeast coast and the eastern periphery of an upper level ridge extending into the region from the west. Looking Ahead: VFR conditions are expected to prevail through the weekend into early next week as an upper level ridge builds over the Carolinas from the west. Isolated/scattered convection cannot be entirely ruled out at any terminal during the late afternoon/evening hours each day. -Vincent && .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 Sat Jul 23 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...Hartfield NEAR TERM...Badgett SHORT TERM...Hartfield LONG TERM...KRD AVIATION...Vincent CLIMATE...BLAES is the U.S. government's official web portal to all federal, state and local government web resources and services.