219 FXUS63 KTOP 021036 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 536 AM CDT Sat May 2 2020 ...AVIATION UPDATE... .SYNOPSIS... Issued at 256 AM CDT Sat May 2 2020 08Z water vapor imagery and profiler data showed a shortwave moving across NEB with some showers remaining north of the forecast area. Elsewhere a shortwave was moving over southern Manitoba with a closed upper low off the coast of British Columbia and the Alaskan panhandle. At the surface, high pressure was slowly building south into western NEB with low pressure hanging on over the TX panhandle. A prefrontal trough bisected the forecast area with a southerly wind over east central KS and a northeasterly wind across north central KS. && .SHORT TERM...(Today and tonight) Issued at 256 AM CDT Sat May 2 2020 For today and tonight, the main change from prev model runs has been to trend further south with the frontal boundary. Additionally model forecast soundings show stronger inhibition to a surface parcel with a stronger cap near 700 MB. So the better chances for precip look to be overnight when the GFS and ECMWF show a subtle shortwave moving overhead. Differences in the models handling of this wave lead to some uncertainty in the better location of the precip and the NAM seems to be quite dry compared with other solutions. So have left POPs in the 30 to 50 percent range. Highs today may be dependent on how much insolation there is heading into the afternoon. The NAM and GFS develop some stratocu within the warm sector this afternoon while increasing mid level clouds are progged to move along the NEB state line. This combined with cooler temps at 925 and 850 MB suggests highs will be a few degrees cooler. The bigger change is likely to be across the northern counties where northeast low level winds prevent any significant warm air advection. Lows tonight should remain mild with clouds hanging around through sunrise. .LONG TERM...(Sunday through Friday) Issued at 256 AM CDT Sat May 2 2020 Think the upper wave along with the precip will be exiting to the east early in the day Sunday. Another shortwave is progged to move across the central plains on Monday with a reinforcing cold front moving through Monday night. So chances for precip remain in the forecast. The bigger uncertainty in the forecast for Monday is how much will the boundary layer recover ahead of the cold front. The GFS seems to be the only solution that brings the warm sector back into northeast KS with the NAM and ECMWF tend to keep an easterly wind across much of the forecast area. This will impact temps and where surface based instability sets up. Although even the GFS forecast soundings maintain some cap over the boundary layer implying elevated storms. But deep layer shear around 55KT would be supportive of organized updrafts and some potential for hail should the instability works its way into east central KS. So this will be something to keep an eye on. Surface ridging is progged to move in for Tuesday and Wednesday keeping temps near normal and precip chances low. An upper level wave potentially could move across the region within northwest flow aloft on Thursday. Differences between the models in the strength of this wave make it hard to have confidence in anything but some low chance POPs for Thursday and Thursday night. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 536 AM CDT Sat May 2 2020 Main question is how widespread precip might be and when will it begin. The 06Z GFS is quite a bit different from the 00Z run and the CAMs seem to show some light radar returns like drizzle before more organized showers develop with an upper level shortwave. At this point think I will focus a VCSH with the shortwave since forecast soundings don't look like a classic drizzle setup. Stratocu deck looks to move in by mid afternoon at around 4 KFT. So VFR conditions should persist through the forecast period. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Wolters SHORT TERM...Wolters LONG TERM...Wolters AVIATION...Wolters