Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 150139 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 839 PM EST Sat Jan 14 2017 .SYNOPSIS... Cool high pressure at the surface will drift offshore tonight. A cold front will drop southward across central NC on Sunday, followed by another chilly surface high pressure Sunday night and Monday. && .NEAR TERM /THROUGH TONIGHT/... As of 300 PM Saturday... Little change in our sensible weather tonight. Abundant low level moisture will aid to maintain a deck of stratus across the region this evening. A passage of a mid level perturbation late this evening/overnight will veer the low/mid level flow to a more wly direction. The downslope component to the flow will help to disperse the low level clouds. This partial clearing may potentially lead to the development of fog with pockets of dense fog possible. Confidence however is not high enough to mention in the forecast nor issue an advisory. Temperatures tonight will either hold steady or fall ever so slowly. Min temps will generally be in the mid 40s. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... AS OF 300 PM Saturday... Sunday, a strong s/w will cross southern New England/northern Mid- Atlantic region. The sfc cold front attendant with this feature will enter our northeast counties by early afternoon and drive southwest, exiting our southern Piedmont shortly after sunset. Similar to the last frontal passage, very little if any rain will occur ahead or along the front. In fact, skies Sunday will be variably cloudy with peaks of sunshine probable, especially across the Sandhills and southern coastal plain. This may lead to a wide range in high temperatures Sunday afternoon, varying from near 50/lower 50s far northeast to the lower 60s southwest. if sunshine is more prevalent than current thinking, afternoon temps may end up 3-5 degrees warmer than forecast. Sunday night, a dry air sfc ridge will build south along the Carolina coast. Meanwhile the the flow in the 925-850mb layer will be veering to a south-southwesterly direction as a waa regime commences. This will lead to the development of another stratus layer along with patches of light rain, primarily over the western Piedmont. This set-up will initiate a hybrid cold air damming event. Min temps Sunday night will vary from the upper 30s northeast to the low-mid 40s southwest. && .LONG TERM /MONDAY THROUGH SATURDAY/... As of 300 PM Saturday... A 1030-1032 mb surface high will settle over the New England coast Monday resulting in a CAD wedge over northern and western NC. The high will shift off the Mid-Atlantic coat Monday night, but the wedge will remain over northwest portions of the area through Tuesday, as the return flow from the high offshore and increasing southerly flow ahead of the approaching front won`t erode it before then. Meanwhile aloft, the closed low over the Baja will swing northeast into the Midwest by Monday and toward the Great Lakes through Monday Night. The aforementioned low will get absorbed in the northern stream Tuesday while a lingering trough/low remains of the southwest U.S. The strength of the low/shortwave as it moves through the Great Lakes and the high ridging over the southeast U.S. will play an important part in how the weather plays out over Central NC Tuesday through Thursday. It is even uncertain at this time when the actual frontal passage will occur. Given all the uncertainty, the forecast confidence is very low at this time, with respect to both temperatures and precipitation. The secondary southern stream low will progress eastward Thursday through Saturday as a strong upper low approaches the Northwest U.S. coast, digging a very deep trough over the western U.S. Although confidence is low, it does appear that another round of precipitation will occur as the low moves eastward in the Mid- Atlantic late in the week/early weekend, but exactly when and how much is far to uncertain to specify at this time. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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AS OF 840 PM Saturday... MVFR ceilings have steadily eroded from west-east this evening, scattering out to VFR at all terminals except KRWI where BKN/OVC ceilings ~1500 ft AGL persisted as of 01Z. Expect RWI to scatter out to VFR by ~03Z. Expect VFR conditions to prevail for the remainder of tonight through noon Sunday, though eastern terminals could see sub-VFR conditions in the form of fog for several hrs prior to sunrise (08-12Z), particularly the RWI terminal. MVFR ceilings are expected to return Sunday afternoon/evening in the wake of a back- door cold front as high pressure into central NC from the N/NE. MVFR ceilings will persist Sunday night into Monday, when conditions will likely deteriorate to IFR at the RDU terminal and IFR/LIFR at the INT/GSO terminals as southerly low-level return flow develops atop the shallow sfc ridge extending SW into central NC, resulting in the development of a cold air damming wedge. Conditions may briefly improve on Tue as the CAD wedge weakens in response to strengthening southerly flow in advance of a cold front approaching from the west, before deteriorating Tue night into Wed as low ceilings/rain overspread the region along/ahead of the cold front, which is expected to cross central NC Wed afternoon. VFR Conditions will return to all terminals in the wake of the cold front Wed night and Thursday. -Vincent
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...KCP AVIATION...Vincent

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