402 FXUS63 KTOP 072338 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 538 PM CST Sat Dec 7 2019 ...Update to aviation forecast discussion... .SHORT TERM...(This evening through Sunday) Issued at 137 PM CST Sat Dec 7 2019 A positive tilt upper level trough across the western US will continue to shear apart with the northern stream H5 trough moving east across the northern high Plains Sunday afternoon. The southern stream section of the H5 trough will dig southeast across AZ into western NM. A lee surface trough across the central and southern high Plains will slowly drift east across west central KS and southward across western OK. South-southwest surface winds will gradually advect modified gulf moisture northward across eastern OK into southeast KS Tonight. The weak isentropic lift ahead of the moisture return will cause a stratus deck to develop across southern KS late Tonight, which will overspread the CWA during the morning hours. Tomorrow will become mostly cloudy but south-southwest surface winds should still allow high temperatures to reach the the lower to mid 50s. If we see more breaks in the cloud cover Sunday afternoon, then the PBL will mix a bit deeper, allowing highs to reach into the upper 50s to around 60. .LONG TERM...(Sunday night through Saturday) Issued at 137 PM CST Sat Dec 7 2019 Sunday night through Monday night, the northern stream upper level trough across the northern high Plains will shift east across the northern and central Plains into the upper Midwest through Monday night. Strong low-level CAA across the northern Plains will cause a surface cold front to move southeast across the area late Sunday night into Monday morning. 850mb and surface winds will veer more to the west-southwest as the surface trough shifts east across KS and northern OK. At this time the stronger isentropic lift will be confined to southeast KS and southwest MO, where drizzle or light rain may develop but the light rain or drizzle will probably remain southeast of the CWA. Once FROPA occurs late Sunday night into Monday morning, surface winds will switch to the north-northwest and increase to 15 to 25 MPH with higher gusts through the morning hours of Monday and will continue through Monday afternoon. The strong low-level CAA will cause afternoon temperatures to fall through the 30s. Highs across east central KS may reach the lower 40s before Noon on Monday but fall through the 30s during the afternoon hours. AS the southern extent of the H5 trough moving east-southeast across the northern and central Plains passes east across northern KS, there may be enough ascent for light snow or flurries to develop across the northern half of the CWA during the day on Monday. I don't expect any snow accumulations, since the stronger Q-G forcing will remain well northeast of the CWA. Monday night the center of the cold surface ridge will build southeast across eastern KS. The surface winds will diminish through the night and with skies clearing overnight, overnight lows will fall into the mid teens to around 20 degrees. Tuesday through Wednesday, the upper trough across the eastern US will deepen as if slowly shifts east towards the eastern seaboard. The central and southern Plains will remain under northwesterly flow aloft. Highs will only reach into the 30s both Tuesday and Wednesday. The minor perturbations embedded with the northwest flow will remain northeast of the CWA, so I expect a dry but cold forecast. Overnight lows will drop into the teens Tuesday night. Wednesday night through Saturday, the upper flow will become more zonal across the central and southern Plains. This will help high temperatures to moderate back into the 40s on Friday with upper 40s to lower 50s Friday and Saturday. A mid-level perturbation embedded within the zonal flow will move east across the central Plains and may provide enough ascent for light rain late Friday afternoon into Friday evening. The light rain may mix with snow later Friday night before ending. Any precip accumulations look light at this time. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 527 PM CST Sat Dec 7 2019 No significant changes to the going forecast for the 00Z TAFs. The primary hazard will be the LLWS conditions and a strong southwesterly LLJ strengthens across the area overnight. Still uncertain in stratus deck as the best moisture still looks to far southeast of the area in the low levels. But, will need to watch trends on overall moisture advection into the terminals to better refine this part of the forecast. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Gargan LONG TERM...Gargan AVIATION...Drake