Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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538 FXUS62 KRAH 241457 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 955 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 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.
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&& .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 /12Z FRIDAY THROUGH TUESDAY/... As of 620 AM Friday... Aside from patchy radiation fog that may linger at climatologically- favored RWI for the next hour or so, VFR, generally clear conditions are expected to result from surface high pressure over our region. Outlook: The passage of an upper level trough and accompanying moisture-starved, surface cold front will result in areas of virga from ceilings at or above 8-10 thousand ft Sat aft-eve, but no precipitation is expected at this time to reach the surface. There will be a 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...WSS SHORT TERM...MWS LONG TERM...CBL AVIATION...MWS

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