Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 160526 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 130 AM EDT Fri Mar 16 2018 .SYNOPSIS... A backdoor cold front will push south into central NC overnight, 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 /THROUGH TONIGHT/... As of 1025 PM Thursday... Strong breezy westerly winds have subsided across the region, ending the risk for adverse/erratic fire behavior. However, a dry air mass remains as temp/dewpoint spreads of 25-30 degrees common across the region. 02Z sfc analysis depicts a weak sfc front west-to-east across central VA, about to enter southern VA. This boundary should continue to drift swd overnight being pushed along by a weak s/w seen on water vapor imagery exiting the eastern Great Lakes and crossing northern Mid Atlantic. Not much in the manner of cloudiness associated with the boundary, and with the lower atmosphere as dry as it is, threat for sprinkles appears overdone so will remove from the forecast. Overnight temperatures still appear on track despite the relatively mild mid evening conditions. Min temperatures should mainly be in the 40-45 degree range though closer to the upper 30s/near 40 across the far north. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 305 PM Thursday... Northwest flow aloft during the day will result in subsidence over Central NC Friday. The weather is expected to remain dry through the evening, with generally clear to partly cloudy skies. Winds will still be a bit on the breezy side, with some gusts to around 20 kts in the east, but not nearly as strong as today. The backdoor cold front will remain stalled across the area through the evening as a low pressure system moves through the Midwest toward the Mid- Atlantic. Temperatures will be seasonable, with highs in the mid 50s NE (north of the cold front) and around 70 degrees near the SC border. 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 and there will be an increase in both cloud cover and precipitation chances from the west early Saturday morning. && .LONG TERM /SATURDAY 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/...
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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.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...KC 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.