397 FXUS63 KTOP 010808 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 308 AM CDT Fri May 1 2020 .SYNOPSIS... Issued at 308 AM CDT Fri May 1 2020 08Z water vapor imagery showed a relatively flat pattern over the western two thirds of the CONUS. A couple shortwaves were noted within the pattern, one moving into the northern plains and a second over the southwestern U.S. An upper trough with several pieces of energy were noted over the gulf of Alaska. At the surface, a trough of low pressure was gradually deepening over the central high plains and northern plains. This promoted a southerly flow over the Great Plains with dewpoints slowly rising over the southern and central plains. && .SHORT TERM...(Today and tonight) Issued at 308 AM CDT Fri May 1 2020 For today and tonight, models show little in the way of synoptic forcing impacting the forecast area while forecast soundings maintain an elevated mixed layer over the boundary layer capping surface parcels. So dry weather is likely to prevail. With just some mid and high clouds to offset the low level warm air advection, think highs will warm into the lower and mid 80s across the forecast area. There is decent consensus for the boundary layer to mix to around 850MB and this supports highs in the 80s. Lows tonight should remain mild in spite of some weakening winds. A weak frontal boundary is forecast to slide south overnight causing winds to become light and variable. But there isn't much cold air advection progged so lows are expected to only fall into the upper 50s. .LONG TERM...(Saturday through Thursday) Issued at 308 AM CDT Fri May 1 2020 Saturday and Saturday night will see increasing chances for showers and thunderstorms. The main question for Saturday afternoon is whether storms are able to develop along the frontal boundary. Forecast soundings maintain some inhibition to surface based convection along the front. However it is forecast to become weak in the heat of the day. Deep layer shear looks to be more than favorable for supercell storms if convergence along the boundary is sufficient to overcome the cap. Nevertheless the NAM and GFS suggests some potential for elevated precip to develop near the NEB state line before 00Z. With this in mind have included a slight chance POP for the late afternoon Saturday across northern parts of the forecast area. The severe risk looks to be conditioned on whether the cap hold or not. Overnight Saturday models prog a weak perturbation moving through the westerlies. This may help elevated showers and storms increase in coverage during the overnight hours. So have continued with some chance POPs. Highs Saturday could be a little tricky as models increase low level moisture indicative of some stratocu by the afternoon. Additionally areas north of the surface boundary should see neutral temp advection at best. So in general temps should trend a little cooler. Areas near the NEB state line may only warm into the upper 70s. Sunday looks to be mainly dry. There could be some lingering showers across far eastern KS around day break. But with the perturbation quickly passing east of the forecast area, there doesn't look to be much forcing for vertical motion. Additionally Surface ridging should push the deeper moisture south of the forecast area. Highs Sunday look to be in the mid and upper 70s with the help of some insolation by the afternoon. Precip chances return for late Sunday night and through Monday night. Return flow is progged to redevelop late Sunday night with increasing moisture advection. Then an upper wave moving across the northern plains is progged to bring another frontal boundary through the area late Monday and Monday night. There remains some differences among the operational solutions such that confidence in the forecast is not all that great. So POPs remain in the chance category. Surface ridging for Tuesday through Thursday is expected to bring cooler weather the the central plains with highs generally around 70 or in the lower 70s. Lows look to be in the 40s. There is a slight chance for precip Thursday as the surface ridge slides east and return flow redevelops. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1150 PM CDT Thu Apr 30 2020 Continued VFR conditions forecast for the period. LLWS seems to be underway by looking at radar wind profiler data. The LLJ should be fairly strong into the overnight period, so have increased the LLWS by up to 45-50kts. The surface winds look like they are decoupling sooner than previously forecast as well. Still looking at an end time for WS conditions around 14Z. Winds mix down by mid morning and should have little problem gusting above 20kts and as high as 30kts at times. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Wolters SHORT TERM...Wolters LONG TERM...Wolters AVIATION...Drake