018 FXUS63 KTOP 122327 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 627 PM CDT Thu Aug 12 2021 ...Update to aviation forecast discussion... .DISCUSSION... Issued at 256 PM CDT Thu Aug 12 2021 The main focus for this forecast is the chance for storms today and tonight. This afternoon, a weakly defined stationary front was located across northern KS and extended into southeast NE and southern IA. The stationary front will remain across northern KS into southeast NE through most of the afternoon hours but will begin to push southward this evening. Thunderstorms continue to develop along the front as elevated instability and steep lapse rates combine with weak convergence along the boundary. The SPC mesoanalysis page has about 5000 J/Kg CAPE in a nearly uncapped environment near the boundary. Effective and 0-6 Km shear on the other hand appears to be minimal with values of 20 knots or less. Therefore, some pulse type storms this afternoon and early evening could become severe with damaging wind gusts to 60 mph and quarter size hail. However, if any updraft becomes more organized with mesoscale rotation, there may be a larger hail threat with the very high CAPE values. Models are all over the place when it comes to the evolution of the front/storms this evening and tonight. Continued development along the boundary across northern Kansas this afternoon, followed by a congealing of storms into a line segment along the main synoptic front this evening is the most likely scenario based on the 12 UTC suite of data available. Scattered to numerous showers and thunderstorms could continue along and north of the front into Friday morning. There may be some brief heavy rainfall within the line of storms tonight. A weak mid-level wave may swing through northeast KS Friday and Friday night. Off and on showers and thunderstorms are possible through the day Friday as a result. Shower and thunderstorm chances should gradually decrease through the overnight hours as the front, mid-level wave and associated lift exit the area. Northeast winds, cloud cover and periods of showers and thunderstorms will keep temperatures quite a bit cooler Friday with highs in the low to mid 80s. Showers and thunderstorms are possible again Saturday as return flow kicks in and another mid-level wave swings through the northwest flow aloft. Cooler temperatures and occasional showers and thunderstorms will highlight the forecast through mid-week as we remain under the influence of northwest flow aloft and lee surface troughing. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 625 PM CDT Thu Aug 12 2021 While showers and storms have generally avoided the main TAF sites so far, they should become more widespread again by the late evening hours. Ceilings will mostly remain VFR, but visibilities in the heavier showers and storms could become MVFR and locally worse. Conditions gradually improve by late tonight, with any leftover showers or storms exiting by late tomorrow morning. In general, winds will be from the northeast around 5 kts behind the cold front, but will be widely variable around any stronger convection. && .TOP WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM CDT this evening for KSZ010>012-022>024- 026-036>040-054>056-058-059. && $$ DISCUSSION...Jones AVIATION...Reese