Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 110810 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 310 AM EST Mon Dec 11 2017 .SYNOPSIS... High pressure will extend over the Gulf of Mexico and southeast states today through tonight. A dry cold front will cross North Carolina Tuesday, ushering in even colder air for mid week. && .NEAR TERM /today through tonight/...
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As of 240 AM Monday... Calls to counties in the NW part of the forecast area, where some snow lingered on grassy areas, reveals that the roads dried out considerably with the sunshine and breeze yesterday. While some isolated icy spots likely remain this morning, widespread travel problems are not anticipated, so a black ice advisory will not be needed. Within a stable column featuring fast WNW flow, the passage of a band of elevated moisture aloft -- along a 700 mb trough axis now crossing the area -- has kicked off some orographically enhanced mid clouds over the N Piedmont early this morning. Once this moisture band passes to our east closer to daybreak, we should see these clouds dwindle, leaving generally sunny skies today. Surface high pressure will continue to span the Gulf of Mexico and FL, with SSW to SW surface winds over NC. Latest model runs show thicknesses just a bit below normal this morning but rising nicely through the day within warm air advection, although cooler air may hang in longer across the far northern CWA. Expect highs from the upper 40s N to the mid 50s S. Our attention then turns to the potent mid level clipper diving SE over the Upper Midwest this morning. This wave, and its accompanying surface cold front, will drop SE then E into the mid Miss Valley and Ohio Valley through tonight. As it approaches, we`re likely to see increasing mid clouds late this afternoon through tonight, especially across the NW and N, with weak moist upglide noted on the 310K surface. Improving low level moisture, especially over the NW CWA, may induce patchy stratus as well overnight. The trend to partly to mostly cloudy skies and the light SW breeze holding up overnight should temper cooling somewhat, yielding lows of 30-36, not far from normal but much milder than the last couple of nights. -GIH
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&& .SHORT TERM /Tuesday through Tuesday night/...
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As of 310 AM Monday... The upper level shear axis and corresponding dry surface cold front will traverse the area Tuesday, arriving in the mid morning W, and shifting east of the area during the mid afternoon. Skies should remain partly to mostly cloudy through the morning, with a gradual improving trend to fair to partly cloudy skies in the afternoon, with a combination of thin mid and high clouds along with flat cu as moisture is trapped near the top of an increasing boundary layer mixed depth. The cooler air mass will be building in from the west, such that it appears that the mountains will initially block the coldest air, and we should still reach highs from the upper 40s NW to the mid 50s SE, although a stout breeze with frequent gusts around 20 kts will make it feel chillier, especially late in the day as the dewpoints plummet. While the initial cold front will be moving to our east by mid afternoon, the more prominent cold/dry air surge will arrive late Tue afternoon through the evening, as a strong vorticity max dives through the trough base across NC, with the dynamic trop dropping to around 650 mb. Some enhanced cloudiness and perhaps a burst of stronger wind gusts may accompany this trough passage. Otherwise, skies will clear out Tue night, and temps are expected to bottom out in the 20-25 range. These readings with a steady NW breeze will bring the wind chill down into the low teens over much of the area. -GIH
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 230 AM Sunday... The quieter weather pattern continues mid week, as general troughing in the east gives way to a more zonal pattern toward the end of the period. Wednesday looks to be the coldest day across central North Carolina, with afternoon highs failing to reach the 40 degree mark under a brisk northwest wind. Southerly to southwesterly flow returns early Thursday, allowing a brief warmup to more seasonable temperatures to take place. Around this same time, an area of low pressure looks to develop off of the Carolinas, introducing shower chances into the forecast Friday afternoon and evening. Model differences take hold at this point, with a much wetter and more amplified GFS model introducing an additional wave or two of precipitation to the region before the end of the weekend, while a much drier ECMWF keeps us under high pressure. For now, have limited shower activity at the end of the period until better consensus is observed. && .AVIATION /06Z Monday through Friday/... As of 1240 AM Monday... VFR conditions are a near certainty for the next 24 hours, as a surface high pressure ridge extends into the area from the WSW. Vsbys will be unrestricted, with no cigs. Surface winds will be light, under 8 kts, from the W, shifting to SW then S late today into tonight. Looking beyond 06z Tue: There is a low-confidence chance of sub-VFR conditions at GSO/INT early Tue morning (08z-12z) with increasing low level moisture ahead of the approaching dry cold front. Winds will shift back to northwesterly after frontal passage Tue. Otherwise, VFR conditions will dominate through at least Thu night. Sub-VFR conditions are possible with rain chances increasing Fri as an upper trough approaches. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...JJM AVIATION...Hartfield

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