Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 220317 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1017 PM EST Tue Feb 21 2017 .SYNOPSIS... High pressure extending along the East Coast will move offshore tonight. A slow-moving upper level trough will cross the Southeast and Mid Atlantic states through Wednesday night. && .NEAR TERM /THROUGH TONIGHT/...
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As of 950 PM Tuesday... Cloud cover continues to increase across the area overnight in advance of split mid level trough to the west of the area. However, with the main energy aloft expected to pass to the south of central NC, coupled with a dry low and mid level air mass to start, expect only small chances for rain overnight. The best chance of rain is expected across the far west/northwest piedmont where we may see some spotty waa showers in advance of a mid/upper level low tracking across the deep south. With gradually increasing and thickening clouds from the west to east, expect lows will generally range from the mid to upper 40s NE to the lower 50s SW (with maybe even a few mid 50s far SW).
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&& .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... As of 650 PM Tuesday... The light low level flow from the E and SE will keep low level moisture streaming into the area, banked up against the higher terrain, resulting in partly (east) to mostly (west) cloudy skies Wed. Forcing for ascent remains fairly weak, as the weak mid level flow limits DPVA. Moist isentropic upglide will also be weakening through the day, confirmed by GFS precip progs showing a batch of morning precip over the NW Piedmont shifting ENE across VA where upglide will be deepest. The very weak and shallow moist upglide will persist through Wed night, with stratus, patchy fog, and a risk of drizzle or very light showers, particularly over the west. But models continue to generate very little to no precip over most of our CWA as the weakening mid level shear axis shifts to our east and 850 mb flow decreases and become more westerly, yielding a stagnant column with plentiful moisture in the lowest few thousand feet. Aside from good chance to low-end likely pops in the extreme NW Wed morning, expect fairly low chances for much of the area from midday Wed through Wed night. Expect areas of fog to develop late Wed night as dewpoints steadily climb. With thick cloud cover lodged over the NW Piedmont Wed and greater sunshine over the east with continued very warm thicknesses, we`ll see wide-ranging highs Wed, from around 60 NW to the lower 70s SE. Lows Wed night around 50 to 55. -GIH && .LONG TERM /THURSDAY THROUGH TUESDAY/... As of 300 PM Tuesday... Thursday is starting to look pretty dry as a low pressure system moves across the Florida Peninsula and into the Atlantic. A low pressure system to the west is slower to develop then model solutions showed over the last several iterations. This leaves central NC in a moisture gap for much of the end of the work week with both Thursday and Friday looking drier and fairly warm with highs in the low to mid 70s on Thursday and in the mid to upper 70s on Friday. As the parent low makes its way to the Great Lakes region it will push a cold front eastward over the Appalachians and into central NC on Saturday/Saturday evening. The tail end of the moisture moves across the state with northern areas of the forecast area more likely to get rain than southern areas. QPF looks very meager on the raw model output but there will be some instability around and if some showers or thunderstorms were to form some areas could locally see up to a half of an inch of rain but this is likely to be the exception rather than the rule. Thus not as much help to the abnormally dry situation as we had hoped. While Saturday will still be warm ahead of the front with temps in the mid to upper 70s, the airmass does modify on Sunday and high temps drop back near 60 degrees which is much closer to normal this time of year. Temperatures will modify back through the 60s on Monday and back towards the 70s on Tuesday with dry conditions expected. && .AVIATION /00Z WEDNESDAY THROUGH SATURDAY/... As of 650 PM Tuesday... VFR conditions will continue through this evening as mid and high level clouds increase from the southwest. Tonight, low pressure will move into the Gulf Coast states, sending low level moisture northward to the Triad/Triangle and eventually the coastal plains. Will start to see sub-VFR cigs and vsbys working to most terminals after 06z with best threat of any rain over INT/GSO, with drizzle toward RDU and RWI after 08z. With high pressure keeping flow off the Atlantic will see some fog as well, so vsbys could drop to IFR, though confidence is not high enough to add in the terminals except INT closer to the foothills. As we head into Wednesday will be tough to dislodge the lower cigs but models favor most sites going to VFR after 15z, though in-situ damming over the Triad should keep INT/GSO IFR til the end of this taf period. Looking ahead: Expect cigs in the MVFR/low end VFR range to persist through Wednesday afternoon, mainly west of RDU. With continued southeast flow through Friday, the early-morning sub-VFR cigs and visbys will likely be a reoccurring theme. Low clouds may scatter out enough during the daytime hours for a return to VFR. Winds will slowly veer through the period ahead of the approaching cold front. Showers and sub-vfr conditions will also be possible ahead of the front, which is expected to move through Central NC on late Saturday. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...BSD SHORT TERM...Hartfield/Franklin LONG TERM...ELLIS AVIATION...KC/WP/Franklin

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