Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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297 FXUS62 KRAH 240903 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 403 AM 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/...
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As of 345 AM Friday... WV satellite imagery this morning depicts a positively-tilted, longwave trough stretching from Atlantic Canada swwd to the Gulf of Mexico, including a well-defined perturbation now crossing the Appalachians of NC/VA. This perturbation and parent trough are forecast to move ewd across NC today and reach the coast around 00Z, with following shortwave ridging/height rises, and associated clear skies expected to expand across cntl NC. A lower amplitude, mostly shear vorticity maxima now stretching from the upr Midwest wwd to the cntl Rockies will meanwhile approach from the west today, then cross NC with little more than a band of cirrus overnight. At the surface, 1019 mb surface high pressure centered this morning near the Chesapeake Bay will continue to extend swwd across the Carolinas and sern US through tonight, while a wavy frontal zone and associated unsettled conditions stretching from the ern GOM newd across cntl FL will remain harmlessly (for cntl NC) well offshore the sern US coast. Temperatures will continue to modify in association with the modifying/lingering surface ridge, with highs in the mid 50s to lwr 60s, and lows, with strong radiational cooling conditions once again, in the lwr to mid 30s.
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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 likely arriving too late 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.
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&& .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 /06Z FRIDAY THROUGH TUESDAY/... As of 130 AM Friday... Aside from patchy radiation fog that will be most likely to affect climatologically-favored RWI this morning, surface high pressure will maintain VFR, generally clear conditions across cntl NC. Outlook: The passage of a moisture-starved cold front will result in a small chance of a VFR shower or sprinkle Sat eve, followed by a similarly small chance of sct to bkn MVFR stratocumulus at FAY and RWI, in sly return flow around offshore high pressure, Tue aft. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...MWS LONG TERM...CBL AVIATION...MWS is the U.S. government's official web portal to all federal, state and local government web resources and services.