Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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265 FXUS63 KTOP 220041 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 741 PM CDT Tue May 21 2024 .KEY MESSAGES... - Thunderstorms move east of the area early this afternoon. - Next round for thunderstorms is expected Thursday night and Friday morning. There is a risk some of these could be severe. - Seasonal spring weather is forecast for the weekend with occasional chances for showers and storms and mild temps. && .DISCUSSION... Issued at 234 PM CDT Tue May 21 2024 19Z water vapor imagery shows a shortwave trough lifting northeast through eastern NEB. Radar and surface obs show a frontal boundary pushing through northeast KS and extending through southeast KS. 18Z TOP RAOB showed the slightest bit of MLCIN still ahead of the front. CAMs have been consistent in showing convection developing and quickly moving east this afternoon and nothing that we can observe suggests anything different. So think thunderstorms will be east of the forecast area by 4 pm or so. SSW low level winds and an effective straight line hodograph suggests storms may have to mature some before a tornado risk is realized, likely east of the area. But copious amounts of CAPE (3500 J/kg MUCAPE) would support rapid development and a very large hail and damaging wind risk before storms move east. Tonight models show a weak shortwave passing overhead late in the period and Wednesday morning. Instability will be greatly limited by dry air behind the front but there could be enough vertical motion for some elevated showers through the morning hours. Not sure how widespread it may be with much of the QPF progs only showing a hundredth or two if any precip at all, so have kept POPs around 20 percent. After Wednesday morning, the next chance for showers and thunderstorms looks to come late Thursday and into Friday morning as southerly low level winds advect moisture back north and another frontal system moves in from the northwest. Models show bulk sheer to be rather weak in the 20KT to 40KT range ahead of the boundary, but CAPE could be sufficient for some intense updrafts. Forecast hodographs are a little concerning ahead of the boundary but soundings suggest storms would be elevated. So will need to keep an eye on the potential for a nocturnal tornado risk as models forecast 0-1 SRH of 200-400 m2/s2. There is the potential for a couple low amplitude shortwaves passing through a quasi zonal pattern Saturday night and again Monday. So have kept the chance POPs that the NBM has. The GFS and ECMWF show occasional boundaries making into KS through the extended. This should keep temps a little more seasonable with highs in the 70s to around 80 and lows in the 50s. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 622 PM CDT Tue May 21 2024 Expect VFR conditions for the next 24 hours. The gusty WNW winds will become light from the northwest after 8 PM this evening. The SCT-BKN strata CU with bases above 4000 feet will begin to scatter out later this evening. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Wolters AVIATION...Gargan