Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 160706 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 300 AM EDT Fri Mar 16 2018 .SYNOPSIS... A backdoor cold front will push south into central NC early Friday, then stall in our vicinity through Saturday. An area of low pressure will cross the area Saturday night, dragging the front southward. This will allow an area of high pressure to build into the Carolinas on Sunday. && .NEAR TERM /TODAY THROUGH TONIGHT/... As of 300 AM Friday... 06Z sfc analysis depicts a weak sfc front draped west-to-east across south central VA. This boundary should continue to drift south of the VA/NC border overnight as a secondary shortwave depicted well on water vapor crosses the central Appalachians ejecting off the Mid Atlantic Coast by mid morning. With an extremely dry airmass remaining at the surface, there is little in the way of a precipitation/cloud threat during this period. Thus, overnight temps still appear to be on track, mainly dictated by the eventual position of the front just prior to sunrise. Min temperatures should mainly be in the 40-45 degree range though closer to the upper 30s/near 40 across the far north Friday morning. Skies will remain mostly clear on Friday, with winds picking up as mixing is allowed mid morning. Gusts are expected once again Friday afternoon, however, they shouldn`t be quite as robust as what was seen during the day Thursday. Expect sustained W/NW winds between 5 and 10kts with gusts of 15 to 25kts possible at times. Afternoon temps will remain near to above normal, dependent on how far the surface boundary is able to slip south early Friday morning. Have raised temps area wide from earlier forecasts banking on a slower progression of the front. Temps should touch the low 70s south/east with lower 60s prevalent in the Triad/Northern Piedmont. Mid to Upper-Level Clouds will overspread from west to east after dusk as a developing low progresses east toward the area. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... As of 300 AM Friday... The front will begin to lift northward as a warm front ahead of the approaching system toward daybreak Saturday. As a result, southerly warm, moist advection will begin, allowing for an increase in both cloud cover and precipitation chances from the west early Saturday morning. Precipitation amounts don`t look too impressive across our area, as the surface low occludes over the Ohio River Valley. Best chance of light precipitation arrives Saturday afternoon and overnight into Sunday morning as the remnants of the Low shifts overhead. In all, less than a quarter inch of rain is expected across the forecast area, with the higher amounts likely across the Northern Piedmont. Temperatures will remain seasonal, with 60s prevalent Saturday afternoon and lows dipping into the upper 30s/lower 40s overnight into Sunday morning. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 320 PM Thursday... High latitude blocking (near Greenland), which peaked in late Feb and early March, will become increasingly dominant once again during the next several days. An associated negative NAO pattern, with a negative height anomaly tucked beneath (equatorward of) the ridge, will maintain confluent flow aloft over the Northeast and mid Atlantic. This pattern will consequently cause upstream shortwave perturbations to get sheared on a sly track across the srn middle Atlantic states, with associated episodes of Miller "Type B" cyclogenesis along the srn fringe of cold air damming highs anchored by the confluence aloft. Two such episodes, and associated high to likely probability of rain/showers, are expected to occur Sat-early Sat night, and again Mon-early Tue. In both cases, nrn, climatologically-favored counties are likely to remain in the cooler and more stable wedge air mass, while srn areas experience warm sector warmth, and a slight chance of thunder. While the bulk of the rain during the medium range will occur with those two events, with a quarter to half inch from each, cyclonic flow and cool temperatures in continued troughing aloft over the middle Atlantic states, will favor variably cloudy skies, a slight to small chance of mainly diurnal showers, and below average temperatures mid to late week. && .AVIATION /06Z FRIDAY THROUGH WEDNESDAY/... As of 130 AM Thursday... 24-Hour TAF Period: VFR conditions continue across all TAF sites early Friday Morning. Winds have subsided, with light to moderate westerly flow between 5 and 12kts expected to continue through daybreak. Clouds will remain FEW/SCT overnight and generally 9KFT or higher across the eastern TAF sites. A cold front will drift south through the area and stall on Friday, allowing winds to pick up periodically, although, they should remain weaker than the gusts witnessed on Thursday. Expect gusts generally between 15 to 25kts. A general shift from W/NW to E/NE will occur toward dark Friday night. Looking ahead: VFR conditions will hold through much of Saturday as the region finds itself on the backside of a backdoor front that is expected to stall near the Carolina border. Upper level disturbances tracking ESE across the area (along the frontal zone) will bring increasing chances for sub-VFR conditions Sat/Sat night. VFR conditions may return briefly Sun, then another threat of sub-VFR conditions is possible on Monday likely persisting into the middle of next week. Confidence is not high during the Sat-Mon time frame, with wide variation among models regarding timing of these disturbances, so aviation interests should check back for the latest. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...JJM SHORT TERM...JJM LONG TERM...MWS AVIATION...JJM/KC is the U.S. government's official web portal to all federal, state and local government web resources and services.