Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 071815 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 115 PM EST Wed Dec 7 2016 .SYNOPSIS... Weak high pressure will settle over the Carolinas today. An arctic cold front will move through the area Thursday. && .NEAR TERM /THROUGH TONIGHT/... As of 940 AM Wednesday... Mostly clear skies across central NC this morning, except for in the southern Piedmont where fog has been slow to disperse, though visible satellite imagery is finally showing signs of improvement. High pressure will settle over the area today between a low departing tot he northeast and an arctic cold front moving through the Midwest. Skies will remain clear for most of the day in most areas, but some of the low-level moisture in the Coastal Plain may result in scattered cur this afternoon, while abundant moisture over SC will inevitably return north across the western Piedmont this evening as the flow veers to southerly ahead of the cold front. None of this will have an impact on afternoon highs, which MAV/MET MOS suggest will be in the mid to upper 50s in relatively hallow mixing below the subsidence inversion. -BS Tonight...Models have been pretty consistent in showing some isolated showers/sprinkles accompanying the front, with the front expected to approach the Triad right around daybreak Thursday. Uniform lows in the upper 30s to lower 40s. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... As of 320 AM Wednesday... Shallow moist upglide ahead of the leading edge of the Arctic intrusion spreading west to east through the area on Thursday will support a broken band of very light rain showers/or sprinkles with abrupt clearing in it`s wake owing to the strong cold dry air advection. In fact, we could see temperatures falling across the western piedmont by the afternoon. Highs ranging from lower 50s NW to upper 50s southeast. Strong CAA will continue Thursday as expansive Arctic high begins east into the region. Overnight lows in the mid 20s to upper 20s with a steady wind 7kt breeze resulting in chill values in the teens. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 205 AM Wednesday... Expect cold/brisk conditions on Friday with highs in the upper 30s to lower 40s and a brisk NW breeze assoc/w strong cold advection as 1040 mb arctic high pressure builds eastward from the central plains toward the Appalachians in the wake of the cold frontal passage late Thu/Thu night. Expect chilly lows in the upper teens to lower 20s Sat morning as the arctic high settles over the Carolinas from the west Friday night, with highs on Sat similar to Friday albeit a few degrees warmer. Forecast confidence decreases significantly in the Sun-Tue time frame when the GFS/ECMWF differ by as much as ~24 hours with regard to the timing/evolution of the next upper wave/cold front approaching from the west. The GFS indicates a weaker, more progressive wave with an attendant cold front moving offshore Sun night. The ECMWF, however, indicates a more potent upper level wave /attendant sfc low/ and suggests the associated cold front will cross central NC Monday afternoon, exiting offshore late Monday evening into Monday night. With the above uncertainty in mind, will make little change to the prior forecast Sun-Tue. -Vincent && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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As of 115 PM WEDNESDAY... Clear skies and VFR through early evening. The main forecast issue overnight will how quickly sub-VFR conditions return, and given wide ranging solution from our models, this is a rather low confidence forecast. Brief clearing this morning has resulted in clear skies and VFR this afternoon, but there is ample low-level moisture south and east of the area to support the return of low clouds tonight as weak warm advection develops ahead of a cold front in the Midwest. There are starkS differences between the NAM/GFS and RAP/HRRR, with the RAP and HRRR indicating IFR and LIFR stratus as early as 03Z. However, with light wind, its possible some fog may develop, and this would make more sense around KRWI. In general, expect A mix of LIFR, IFR, and MVFR conditions areawide by 06-08Z, with some patchy light rain also possible. The aforementioned cold front will cross the area between 12Z and 18Z Thursday, clearing out the low clouds and possibly consolidated the precip into a few showers that will exit to the east by midday. West-northwest winds will increase to 8-12kt, with gusts into the upper teens during the afternoon. Outlook: VFR conditions are expected through the weekend. The next chance of sub-VFR conditions will be early next week.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CBL NEAR TERM...CBL/Smith SHORT TERM...MLM LONG TERM...Vincent AVIATION...Smith

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