Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 241720 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1220 PM EST Fri Nov 24 2017 .SYNOPSIS... High pressure will remain over the Carolinas until a cold front crosses the region Sat night. && .NEAR TERM /THROUGH TONIGHT/... As of 955 AM Friday... Little if any adjustments required to the near term forecast. An area if high pressure at the surface and subsidence behind a weak upper level disturbance exiting offshore will maintain sunny skies across central NC today. After a chilly start to the morning which saw low temperatures as cold as the mid-upper 20s across the Piedmont, the air mass will quickly modify by afternoon. High temperatures this afternoon will be solidly in the 50s with the Sandhills and southern Piedmont warming to around 60. There will be a slight uptick in high level cloudiness late this afternoon into the evening as another weak/weakening upper level disturbance passes overhead. Still, expect chilly overnight conditions with areas of frost highly probable. Min temps by early Saturday will be a few degrees warmer due to the moderating air mass. Overnight temperatures in the low-mid 30s expected. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... As of 355 AM Friday... The models indicate a positively-tilted trough extending this morning from n-cntl Canada wswwd through the Pacific NW will amplify from the Great Lakes sswwd into the GOM on Sat, with the associated trough likely to reach the sern US coast by 12Z Sun. An associated 988 mb surface low now over cntl Canada will migrate ewd through ern Canada, while the trailing cold front will sweep into the cntl Appalachians by 00Z Sun, before spilling across cntl NC Sat night. A mid-high level moist axis preceding the surface front and accompanying the aforementioned mid-upper trough --mostly above 8-10 thousand ft-- will sweep ewd across cntl NC late Sat aft through early Sat night. Already limited low level moisture and associated transport, and wly/downslope low level flow, suggests any light precipitation aloft/virga accompanying the moist axis will not reach the surface, so dry conditions remain favored at this time. It will warm well into the 60s ahead of the front, with any afternoon mostly cloudiness over the wrn half of the forecast area not likely to have an effect on high temperatures due to their late arrival in the diurnal cycle, and offset by downslope/compressional warming. CAA- driven lows, with some radiational cooling potential over the wrn Piedmont late as the MSL pressure gradient relaxes there, favor lows in the mid 30s to lwr 40s. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 340 PM EDT Friday... ...Dry and mild temperatures expected next week... In the wake of the cold front passage Saturday night, mild surface high pressure centered over the Lower MS Valley will build west into the area through Monday, before shifting offshore on Tuesday. Meanwhile aloft, the eastern US trough will lift out as the strong ridge over the Western US de-amplifies as it shifts eastward across the Southern and SE CONUS. As a result, the slightly below normal temperatures(55-60 F)Sunday and Monday will be rather short-lived, with temperatures moderating to above normal levels by Tuesday, likely peaking on Wednesday with afternoon temperatures warming well into the 60s and possibly even near 70 across the southern coastal plain and Sandhills. The latest 00z/24 solutions of the GFS and EC have come into much better model agreement with the upper trough ejecting out of the Rockies Wednesday and Thursday, with the general consensus tracking the sheared system well north/northwest of the area. This will favor a continuation of dry and mild conditions through Thursday. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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As of 1220 PM Friday... There is a high probability that VFR parameters will persist across central NC through Sunday. An upper level disturbance and accompanying sfc cold front will cross our region Saturday night. While clouds will thicken and lower late Saturday through Saturday night, ceilings are expected to remain in the VFR category, likely no lower than 5000 ft. Sfc winds Saturday ahead of the front will be swly, mainly less than 10kts. Sfc winds behind the front Sunday will be nwly and less than 10 kts. The next threat for sub VFR ceilings appears to be late Tuesday through early Wednesday, mainly in vicinity of KRWI, KFAY, and potentially KRDU, as a deck of stratocu may spread into the region from the coast.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...WSS SHORT TERM...MWS LONG TERM...CBL AVIATION...WSS

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