Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 200709 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 310 AM EDT Wed Sep 20 2017 .SYNOPSIS... A weak upper level trough will move into central NC later today, then drift sewd through Thursday. Otherwise, an upper level high over the Ohio Valley and Tropical Cyclone Jose meandering off the southern New England coast will result in warm and dry conditions across central NC through the rest of the week. && .NEAR TERM /THROUGH TONIGHT/...
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As of 310 AM Wednesday... Little change required to the near term forecast. An upper level disturbance dropping sewd from the TN Valley will cross our region later today and tonight. This system interacting with a slightly unstable air mass, characterized by MLCAPE values 500-1000 J/kg Wednesday, will trigger a few showers and t-storms late today into the evening hours. Based on latest radar trends/observations, the NAM and associated subsets appear overdone with their precip presentation later today and tonight. Favored PoPs closer to the drier GFS/ECMWF. Based on the expected path of the disturbance, bulk of the isolated-scattered convection will occur west and south of Raleigh, roughly from the Triad sewd into the Sandhills. Severe weather parameters weak or non-existent so not expecting the storms to reach severe criteria. Still appears that high temperatures today will average a solid 5-8 degrees above normal, ranging from the upper 80s to around 90. When the humidity is factored in, heat indices in the lower 90s will be common, especially across the coastal plain and the Sandhills. Tonight, the disturbance sliding to our south will maintain a threat for a few showers basically across our southern counties. Otherwise expect clear-partly cloudy skies and somewhat humid conditions. Min temps in the mid-upper 60s.
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As of 310 AM Wednesday... Thursday and Thursday night, our stretch of warm temperatures will continue, with afternoon highs in the 85-90 degree range. the heating of the marginally moist and slightly unstable air mass will support the development of scattered showers and storms, primarily across the Sandhills into the southern coastal plain. Bulk of the convection will dissipate with loss of heating though isolated showers/storms still possible through midnight near the South Carolina border.
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&& .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 230 AM Wednesday... Central NC will generally be under the influence of high pressure through much of the extended forecast period, resulting in a predominantly dry forecast. However, a weak trough over the region could result in some showers on Friday, primarily in the southwest, but chances are no more than slight. Also, expect skies to be mostly sunny/partly cloudy through the weekend with highs in the mid to upper 80s and lows in the low to mid 60s. The forecast for Sunday onward remains somewhat uncertain, but the medium-range models are starting to trend closer to one another. The forecast will still depend on the track of Maria, which will depend on what happens with Jose. As a result, still have below average confidence in the forecast for Monday and Tuesday. Jose is still progged to meander off the NE U.S. coast through the weekend. Meanwhile, Maria will be moving through the Caribbean, northwestward toward the CONUS. As mentioned above, Maria`s impacts from Sunday onward are still highly uncertain as they will depend heavily on Jose and if/how the two systems interact with one another. For now, expect increasing cloud cover across eastern portions of Central NC Monday and Tuesday. Depending on if Jose comes back inland over VA and how close Maria gets to the NC coast will determine the strength of the winds and chances for convection Monday and Tuesday. Too much uncertainty still exists to speculate on either at this time. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... As of 210 AM Wednesday... VFR parameters are generally expected across central NC through Sunday with a few exceptions. Early this morning, pockets of MVFR visibility are probable through 13Z. After 18Z, a few showers and an isolated thunderstorm may develop as an upper disturbance approaches from the west. The threat for scattered convection will persist into the evening hours, primarily in vicinity of KFAY. In proximity of the heavier showers and storms, expect brief instances of MVFR ceilings and visibilities. On Thursday, there is a small threat for a shower or storm near or south of KFAY. Otherwise VFR parameters should persist at the TAF sites Thursday through the weekend. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...KC AVIATION...WSS is the U.S. government's official web portal to all federal, state and local government web resources and services.