Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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024 FXUS62 KRAH 281940 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 339 PM EDT Tue Mar 28 2017 .SYNOPSIS... An upper-level disturbance and cold front will push across the region today, and offshore this evening. Weak high pressure will follow the front for tonight and Wednesday. Another storm system approach our area Thursday night and Friday, bringing another round of stormy weather. && .NEAR TERM /Through Tonight/... As of 225 PM Tuesday... Little has changed in the forecast philosophy for this afternoon and evening. There continues to be a marginal risk for isolated severe thunderstorms this afternoon. Clearing has allowed for an increase in instability from the Foothills into much of the Piedmont. MLCapes have increased in some areas to near 1000 J/KG over southern VA and portions of the NC Piedmont. Temperatures were rising through the 70s with near 80 at Fayetteville. Dew points were in the lower 50s NW ranging to 60 SE. The wind shift line was located from near Hickory NE to Lynchburg at 200 PM. The main area of instability out ahead of the wind shift line will continue to progress with the wind shift SE into our Piedmont in the next few hours. Cumulus were developing with some organization noted along the wind shift line to our NW. In addition, there was another area to watch from near CLT NE to RDU where another low level boundary was draped. A couple of showers and thunderstorms were already ongoing along these boundaries. Hi-Res models and current data suggest widely scattered thunderstorms will continue to develop along both these features this afternoon as they progress rapidly eastward, exiting the Coastal Plain region by early evening. The favorable instability and timing of the wind shift line is expected to be mainly east of the Triad region; therefore, the isolated severe potential should be confined to the far eastern Piedmont to the coast 20z-23z or so. Even over these areas, MLCapes and many other severe weather parameters especially wind shear are only marginal. Pea to nickel hail may end up being common in most of the stronger cells, with isolated 1 inch hail possible. The action will shift offshore by sunset and dry/quiet conditions will return for tonight. Lows in the 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 /18Z Tuesday through Saturday/... As of 145 PM Tuesday... 24 Hour TAF Period: Generally VFR conditions forecast for the KGSO/KINT areas, with VFR elsewhere outside of widely scattered strong thunderstorms between 19z and 23z, mainly from KRDU eastward to the coast. VFR conditions expected tonight and Wednesday with weak high pressure. 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. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Badgett NEAR TERM...Badgett SHORT TERM...Vincent LONG TERM...Vincent AVIATION...Badgett

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