Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 152256 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 655 PM EDT Thu Mar 15 2018 .SYNOPSIS... High pressure will drift across the southeastern U.S. and off the FL coast through tonight. A backdoor front will move southward into the area late tonight before stalling across the Carolinas Friday into Saturday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 655 PM Thursday... Strong breezy westerly winds, with gusts around 40 mph at a number of locations across central NC, will subside around sunset. While strong gusts are not expected overnight, the difference in pressure between a high over the FL peninsula and a deep sfc low north of New England will maintain a steady wly flow, averaging 5 to 10 mph. Additionally, a weak sfc cold front will drop southward into the northern counties around midnight, drifting to a position in vicinity near or north of highway 64 by daybreak. The atmosphere ahead of the front is quite dry and stable. Some model guidance, however, is depicting enough lift and marginal moisture to produce a few sprinkles, mainly north-northeast of RDU. Overnight temperatures will vary from the low-mid 40s south, to the mid-upper 30s across the far north where slightly cooler air behind the front may filter into the region.
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&& .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 /18Z THURSDAY THROUGH TUESDAY/... As of 155 PM Thursday... 24-Hour TAF Period: High confidence VFR conditions will prevail through the TAF period. Winds continue to be the biggest aviation concern, with west-southwest winds of sustained 12-20 kts, gusting to around 25-35 kts through the afternoon. Gusts will abate tonight as winds become a bit more variable, generally around 5 kts (give or take a few). Some lingering gusty winds are possible again on Friday, especially across the east, with sustained winds around 10 kts and gusts of 15-20 kts during the afternoon. -KC Looking ahead: VFR conditions will hold through Fri as the backdoor front drops into the area and stalls across the Carolinas. 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. 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...
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&& $$ SYNOPSIS...Hartfield NEAR TERM...WSS SHORT TERM...KC LONG TERM...MWS AVIATION...KC is the U.S. government's official web portal to all federal, state and local government web resources and services.