Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 290612 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 212 AM EDT Wed Mar 29 2017 .SYNOPSIS...
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Weak high pressure will move over central NC today and remain in control through Thursday before low pressure brings unsettled weather to the area for Friday and Friday night.
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&& .NEAR TERM /THROUGH TONIGHT/... As of 915 PM Tuesday... Last bit of convection has exited the SE zones over the past hour, in concert with the exiting upper level trough and attendant deeper moisture moving off the Mid-Atlantic coast. At the surface, lead sfc front/trough has pushed east into the area, most distinguishable by the drier/lower sfc dewpoints that have advected into the NC Piedmont and Sandhills. However, it will be with a secondary NELY surge behind a back-door cold front late tonight between 06 to 12z that will bring the noticeably cooler air into the area. NAM fcst soundings and HRRR depict a layer of low-level moisture stratus advect into the area within the low-level NELY flow. Will increase cloud cover the north and northeast. Lows tonight in the lower to mid 50s. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... As of 335 PM Tuesday... Wed-Wed Night: With shortwave ridging aloft, expect mostly sunny to partly cloudy skies and above normal temps in the mid/upper 70s Wed afternoon. Subsidence in the wake of an upper level low moving offshore New England Wed evening will result in pressure rises along the eastern seaboard as an inverted sfc ridge extends southward through the Mid-Atlantic into the Carolinas, the leading edge of which will be marked by a backdoor cold frontal passage /wind shift to the NE at ~15 mph/. Lows Wed night will be determined by the precise timing of fropa. Based on the latest guidance, expect temps ranging from the mid 40s NE Coastal Plain to lower 50s in the SW Piedmont. Thu: In the wake of the backdoor cold front, NE low-level flow will veer to the E/ESE during the day, allowing temperatures to recover into the mid/upper 60s to lower 70s across the Sandhills and SE Coastal Plain Thu afternoon. A cold air damming wedge is expected to develop across portions of the Foothills and N/NW Piedmont as warm advection (via SW H85 flow) strengthens atop the shallow cooler airmass in place near the surface. As a result, broken/overcast cloud cover should largely offset diurnal heating across portions of the N/NW Piedmont where highs may struggle to exceed the mid 50s, esp in Forsyth county. -Vincent && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY NIGHT/... As of 335 PM Tuesday... Thu night: Expect an increasing potential for elevated showers across the western half of the state (west of Highway 1, primarily the NW Piedmont) between midnight and sunrise Fri as an upper level low progresses across the central MS river valley into the western TN valley and low-level warm advection strengthens downstream over the Carolinas. Expect lows Fri morning ranging from the mid/upper 40s (N/NE) to lower 50s, warmest Sandhills and SW Piedmont. Fri-Fri Night: Uncertainty in the evolution of the approaching upper level low and attendant sfc cyclone has decreased over the past 24 hours now that the ECMWF is in much closer agreement to the GFS, however, confidence in temperatures, precip amounts and convective intensity remains relatively low due to the expected presence of a CAD wedge and potential for upstream convection /latent heat release/ to alter low-level height/wind fields over the Southeast/Carolinas. Although precip amounts remain uncertain, precipitation chances Friday/Friday night remain solid. As such, have increased pops to categorical (~80%). A potential for organized severe thunderstorms will exist Friday afternoon and evening given the synoptic pattern progged by the GFS/ECMWF, however, the overall extent/character of the threat remains difficult to ascertain at this range, as do forecast temperatures for Fri/Fri night. With the most recent guidance in mind, will indicate highs ranging from the lower 60s in the Triad to the lower/mid 70s in the Sandhills/SE Coastal Plain. A clearing trend from SW-NE is expected in the wake of a cold frontal passage after midnight. Lows Sat morning will depend primarily upon fropa timing, ranging from the lower 50s N/NW to mid 50s S/SE. Sat-Sun night: A potential for isold showers may surface Saturday afternoon east of Hwy 1 if DPVA attendant shortwave energy digging SE along the western periphery of the departing upper level low occurs in vicinity of peak heating. Otherwise, expect dry conditions and a warming trend over the weekend as a shortwave ridge builds east across the Mid-Atlantic and Carolinas. Expect highs in the lower/mid 70s Sat and mid 70s Sunday as a shortwave ridge aloft tracks across the region from the west. Mon-Tue Night: Expect increasing cloud cover during the day Monday and a chance for convection by Tue as the next upper level low /attendant sfc cyclone/ approach from the west. -Vincent && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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As of 210 AM Wednesday... 24 Hour TAF Period: Some concern this morning over the development of some potential fog in the northeastern areas this morning. HRRR visibilities show fog skirting KRWI but not actually occurring at the airport. This may be in part due to earlier rainfall that occurred mainly north of the KRWI area. Closer to sunrise there is some hinting that at least scattered if not broken clouds in the MVFR range may move into the northeast as well and potentially affect KRWI and KRDU. These ceilings could persist through to almost 18Z before lifting later this afternoon. Otherwise expect VFR conditions and northeasterly winds. Long term: A low pressure system will cross the area on Friday through Friday night with the potential for showers and thunderstorms. High pressure with VFR conditions should return for the weekend.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Ellis NEAR TERM...CBL SHORT TERM...Vincent LONG TERM...Vincent AVIATION...Ellis

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