Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 040744 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 245 AM EST Sun Dec 4 2016 .SYNOPSIS... High pressure will extend into the area from the north this morning. Low pressure will track from the Gulf Coast across the Southeast states late today through tonight, before moving off the coast Monday morning. High pressure will build in briefly from the north Monday afternoon, then a second stronger low pressure system will cross the Gulf States and Carolinas Monday night through Tuesday. && .NEAR TERM /today through tonight/...
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As of 245 AM Sunday... Surface high pressure nosing southward from the central Appalachians into central NC is capped by a broad mid level ridge axis this morning, however this will soon give way to deepening moisture as the axes of both ridges shift eastward and IVT strengthens over the area, with the arrival of a weak mid level perturbation which flattens the mean flow over our region. Somewhat deep but weak moist isentropic upglide is already underway across western NC into the western/southern Piedmont, topped by weak upper divergence, although the subcloud layer here remains fairly deep, causing precip to be light and more patchy. This scenario should persist through much of this morning as the initial forcing for ascent will be rather weak with high cloud bases. But models show upglide gradually strengthening through the 285K-305K depth by early afternoon and remaining strong and deep over central/eastern NC from mid afternoon through much of tonight, coinciding with the west-to-east passage of the 850 mb SSW-erly jetlet across GA and the Carolinas, as well as with weak low pressure tracking from the Gulf Coast across the coastal Carolinas. Expect rain chances to increase by midday to categorical SW ranging to just slight chances NE where the surface ridge will hang on longer, all in line with consensus of large scale models as well as recent CAM runs. This will be followed by a trend to categorical pops over all of central NC by mid-late afternoon, persisting through midnight. Expect amounts through tonight to range from around a half inch in the north to around an inch across the south. This upglide will diminish late tonight as the low level jet shifts to our east, with the onset of downslope-directed low level flow and the departure of the weak surface low and weak mid level wave. Expect pops to trend down to chance NW but stay categorical in the SE until just before dawn. Below normal thicknesses with clouds and rain falling into a lingering stable pool favor chilly highs from the mid 40s NW to lower 50s E. Lows tonight 40-46. -GIH
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&& .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/... As of 340 PM Saturday... Rain Sunday night will taper to light rain or drizzle late as the initial surge of lift shifts to our NE and the initial wave of low pressure is forecast to move NE off the coast by 12Z/Monday. Temps should hold steady in the 40s/lower 50s NW to SE. The passage of the wave will bring a break in the rain chances for most of Monday. This occurs as another (this time weaker) surface high builds in from the north Monday. Some residual affects of the CAD should linger Monday in the heart of the Piedmont with plenty of clouds and some light mist or drizzle. Low clouds early may give way to breaks in the clouds around the edges of the damming Monday afternoon. However, we will undercut highs Monday going below statistical guidance by 5 degrees in the W-N Piedmont (near 50), but go close to guidance where breaks should occur (Sandhills, Coastal Plain) may see lower 60s. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... As of 400 PM Saturday... The parent storm is still expected to take on a "Miller B" scenario Monday night and Tuesday. This means the parent storm tracks NE from the Gulf of Mexico through the Ohio Valley Mon night. As this storm weakens, another develops along the SC coast (coastal front) and tracks along the NC coast Tuesday and Tuesday night. Another hybrid CAD event is expected as surface high pressure is forecast to become established from NY to western SC in the Miller B scenario. Lows Monday night generally in the 40s. Highs Tuesday will hold in the 40s in the Piedmont, with near 60 SE. Some lingering light rain or drizzle expected Tuesday night with temperatures holding steady or slowly rising. Ample moisture from both the Atlantic and Gulf will be pulled into the system and the result will be rain developing again Monday night and continuing Tuesday. The back edge or end of the significant rain should arrive very late Tuesday with models in general agreement on this timing. QPF this time should be heavier, with 1 to 1.5 inches expected. The first very cold air mass originating in Alaska and the Yukon will arrive in the mountains as early as Thursday. Models are trending faster and are more in line with the GFS (preferred solution) in pushing this air mass across the mountains to the coast late Thursday and Friday. Any showers would be rain and prefrontal in the warm air. Wednesday will be mild with decreasing clouds and temperatures in the 60s. Much colder temperatures are expected Thursday through Saturday with the heart of the cold for our region Friday into next weekend. Our coldest lows should be 20-25 and highs mid 30s to mid 40s Friday and 40-45 Saturday. && .AVIATION /06Z Sunday through Thursday/... As of 1245 AM Sunday... VFR conditions will hold through this morning across Central NC, although mid and high clouds will continue to overspread the area from the west. Cigs will stay above 5,000 ft AGL areawide through at least 17z. But conditions will gradually deteriorate this afternoon from SW to NE as surface low pressure and an upper level disturbance track across the Gulf States toward the Southeast. Cigs will drop to MVFR at INT/GSO starting around 18z with light rain spreading in, then at RDU/FAY starting around 21z, and at RWI starting around 02z this evening. Cigs are then expected to drop to IFR at INT/GSO after 21z and at RDU/FAY after 02z this evening. The rain will initially be light as it first arrives today with VFR vsbys holding, however as the rain intensity picks up a bit later today, vsbys will drop to MVFR in the late afternoon (INT/GSO) through evening (RDU/FAY/RWI). Winds will be light mainly from the NE initially before shifting to blow from the E and SE late today into tonight, remaining light. Looking beyond 06z late tonight, high confidence in poor aviation conditions, primarily IFR/LIFR cigs and MVFR/IFR vsbys, dominating later tonight through daybreak Mon. Rain will gradually taper off from NW to SE Monday morning with conditions rebounding to VFR areawide. VFR conditions will dominate from around 18z Mon until around 06z Tue. Then another storm system will cause IFR conditions to return after 06z early Tue morning, lasting through much of Tue with steady widespread rain returning. Rain will end late Tue, although IFR clouds will hold into Tue night. Improvement to VFR is expected Wed, then will drop back to MVFR/IFR Wed night. Cold front passage may bring VFR conditions once again Thu. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Badgett LONG TERM...BSD/Badgett AVIATION...Hartfield is the U.S. government's official web portal to all federal, state and local government web resources and services.