Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 291852 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 250 PM EDT THU SEP 29 2016 .SYNOPSIS... A large upper level low will hold over Kentucky and southern Indiana through Friday, as a surface front holds along the North Carolina Foothills. The upper low will weaken and drift north and northeastward over lower Michigan through the weekend, as the surface front pushes slowly eastward across central North Carolina. && .NEAR TERM /through tonight/...
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As of 250 PM Thursday... Flash flood watch for the far eastern and southeast sections of the forecast area will continue for now, and may need to be extended in area based on further assessment of developing convection. This morning`s band of heavy rain and storms which instigated countless flooding reports this morning was oriented along a band of strong low level moisture transport, strong upper divergence, and focused deep IVT, all of which have weakened and shifted eastward, along with the greatest coverage of moderate to heavy rain. Bands of showers and storms are developing once again over NC this afternoon, pivoting around the KY upper level low, and while the strongest storms are expected to be in the Triad region to the north and NW (where deep layer bulk and effective shear is quite strong and where low level lapse rates are approaching or exceeding 7 C/km) over the next 6-8 hrs, a few strong storms are possible this afternoon into early evening over the remainder of central NC with surface dewpoints solidly in the upper 60s to lower 70s. Instability so far has been marginal despite some insolation, but will continue to monitor. Otherwise, still expect training cells given the band- parallel cell motion, which could push local rain totals up to 2-3" in spots, while many areas outside of such bands may see less than a half inch. Locations which have seen considerable rainfall in the last 24 hours cannot handle much more water and may see a rebounding of flooding with even minor amounts of additional rainfall. Showers and isolated storms will slowly decrease in intensity and coverage later this evening and into the overnight hours with an expected decrease in low level moisture transport, although the persistence of upper divergence especially across the NE and far N CWA will necessitate retaining a low chance there through the night. Areas of fog and stratus should return late tonight. Lows from the low 60s west to upper 60s east. -GIH
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&& .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 445 AM Thursday... On Friday, expect conditions similar to Thursday with the upper level low stalled over the Cumberland Plateau and the attendant cold front stalled over central NC. -Vincent && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 440 AM Thursday... Stubborn upper level low over the Southern Ohio valley will lift slowly north, back over the Great Lakes through the weekend. At the surface, the lingering orphaned surface front will dissipate across the area. With Central NC on the eastern periphery of the deep cyclonic flow and the back-edge of the deeper moisture plume (PWATS ~1.5")lingering over the coastal plain of NC, we`ll continue to see a threat of mainly diurnal isolated to widely scattered showers Saturday and Sunday, diminishing in coverage with each passing day. Temperatures will continue to run slightly above normal with highs ranging from upper 70s north to lower 80s south. The closed low over the Great Lakes will finally open up and weaken as it finally ejects eastward, moving off the New England Coast Monday and into Tuesday. In it`s wake, sfc high pressure building east and south down the Atlantic Seaboard will bring cooler, more seasonable temperatures to the area by Tuesday/Wednesday. Large uncertainty looms for the latter half of the upcoming work week with respect to Tropical Storm Matthew. The NHC official forecast has Matthew near Eastern Cuba Monday evening, with questions as to whether Matthew will get picked up and directed northward by an upper level trough over the Gulf of Mexico. Stay tune and check with the National Hurricane Center for the latest on Matthew. Users are reminded that the average NHC track errors at days 4 and 5 are on the order of 180 and 240 miles, respectively. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... As of 215 PM Thursday... Conditions have improved to VFR over all but FAY, where MVFR cigs lingered, and near GSO where MVFR cigs returned with showers in the vicinity. Periods of sub-VFR conditions -- mainly MVFR but briefly IFR at times -- is expected at all central NC terminal sites through the rest of the afternoon, as scattered to numerous showers and storms form over the area and move swiftly toward the north, generating brief heavy rain, periodic wind gusts, and possible small hail. The shower/storm coverage will slowly decrease through the evening and night from SW to NE, with RWI the last to see the rain threat diminish. With a moist ground and light winds from the SE, widespread IFR to LIFR cigs and MVFR to IFR vsbys are expected to develop at all sites after 07z tonight, lasting until around 13z Fri. VFR conditions expected after that, through the end of the TAF valid period. A few showers may linger through the morning in the east near FAY/RWI. Looking beyond 18z Fri, another round of MVFR showers and isolated storms are expected mainly at RDU/FAY/RWI Fri afternoon into early evening as a surface front shifts slowly eastward into central NC. This front will weaken and dissipate heading into the weekend, allowing the better rain chances to shift to our east. Except for a potential for MVFR or IFR fog/stratus at RWI early Sat morning, VFR conditions will dominate through Tue with low rain chances. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch until 10 PM EDT this evening for NCZ028-042-043- 075>078-084>086-088-089. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Vincent LONG TERM...CBL AVIATION...Hartfield

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