Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 291014 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 614 AM EDT THU SEP 29 2016 .SYNOPSIS... A potent upper level low will stall over the Cumberland Plateau in eastern Tennessee and Kentucky today and Friday, then retrograde north through the Ohio valley and lower Great Lakes this weekend. && .NEAR TERM /TODAY AND TONIGHT/... As of 445 AM Thursday... A busy midnight shift here in central NC, one which began with a severe thunderstorm watch and transitioned into a 100-year rainfall event (ongoing at ~09Z) across portions of the Sandhills (i.e. Hoke/Cumberland/Harnett counties) where as much as 5-8" of rain has fallen over the past 8-12 hours. As such, the forecast discussion this morning will be brief. Several SW-NE oriented lines of convection developed over central NC yesterday afternoon/evening in assoc/w moderate diurnal destabilization, low-level convergence attendant a pre-frontal trough, and diffluent flow aloft downstream of a potent upper level low. During the overnight period, rich low- level moisture assoc/w southerly flow in advance of the approaching cold front has maintained sufficient nocturnal instability for convection to persist, resulting in significant rainfall and /potentially life-threatening/ flooding across portions of Harnett, Hoke and Cumberland counties this morning. Although the cold front may make some slow eastward progress into the area today, the parent upper level low will cut-off /stall/ over the TN valley this aft/eve, and additional eastward progress of the front is unlikely thereafter. As a result, expect a good chance of convection again this aft/eve into tonight. A few severe storms cannot be ruled out, and an isolated flash flood potential will persist. -Vincent && .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 /06Z THURSDAY THROUGH MONDAY/... As of 145 AM Thursday... The two distinct bands of showers and thunderstorms across Central NC are currently in the process of merging into one broader band across the central Piedmont and Sandhills. KRDU and KFAY will be the most impacted terminals, with KRWI to a lesser extent with Sub-VFR conditions in heavy rain along with the potential for gusty winds of 25 to 30 kts. Convective coverage and intensity should gradually decrease towards daybreak. In addition, a blanket of low (LIFR) stratus is expected to redevelop mainly over the Piedmont (INT/GSO) late tonight, before lifting and scattering to VFR with diurnal heating between 13-16Z Thu. That heating, in conjunction with lift supplied by a slow-moving wave of low pressure and associated frontal zone, will also cause showers and storms to re-develop by mid afternoon and linger into the evening. Outlook: Moist low-level air will continue to support early morning stratus/fog Friday morning and possibly again Saturday morning. Otherwise, Drier air is finally expected to filter into the region on Friday, leading to improved aviation conditions through the weekend. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Vincent NEAR TERM...Vincent SHORT TERM...Vincent LONG TERM...CBL AVIATION...CBL is the U.S. government's official web portal to all federal, state and local government web resources and services.