Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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052 FXUS63 KTOP 242342 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 642 PM CDT Fri May 24 2024 .KEY MESSAGES... - Increasing potential for a higher-end severe weather event Saturday evening and night, especially along/south of I-70. - Thunderstorm chances continue into Sunday before a relatively quieter pattern arrives for next week. && .DISCUSSION... Issued at 308 PM CDT Fri May 24 2024 Our most recent cold front has moved off to the south and east this afternoon, as the associated shortwave trough lifts north across the Northern Plains. High pressure quickly moves overhead tonight, allowing the northwest post-frontal winds to calm. Similar to yesterday morning, expecting some very patchy shallow fog towards sunrise, mainly in river valley locations across east-central Kansas. Any fog that does develop will be short-lived, ending once southeast winds increase tomorrow morning ahead of the next system. Attention then turns to the next approaching trough Saturday evening, as low pressure deepens to around 990 mb across western Kansas. Strong mass response ahead of this low will advect higher dewpoints quickly north. Some uncertainty in exactly how quick this occurs, but a multi-model average takes the warm front to around Interstate 70 by mid evening. This mid-evening timeframe (7-9 PM) seems when convection is most likely to initiate towards central Kansas, as stronger mid-level height falls overlap with increasing low-level moisture and decreasing CIN. However if the better moisture is slightly faster or slower than expected, could see convective initiation as early as 5 PM or as late as 10 PM. Initial storm mode is expected to be discrete or semi-discrete supercells, given strong effective shear largely perpendicular to any boundaries. Large to giant hail and damaging winds would be likely with any supercell. Tornado threat would be more dependent on moisture quality and timing, but the faster and deeper moisture scenarios would see a strong tornado potential given 0-1 km SRH quickly increasing as the LLJ ramps up by sunset. As the surface low approaches by late evening and forcing increases, expecting a transition to more of a linear mode. Moisture and low-level shear further increase through late evening as thunderstorms move east. The damaging wind risk will increase and the hail risk will decrease as storm mode becomes more linear. A tornado threat will continue with mesovortex potential within any MCS, given the degree of low- level shear. There are still several questions and potential failure mechanisms regarding tomorrow`s severe weather threat. The biggest is the aforementioned timing of the better moisture`s arrival, which will impact the amount and timing of initial supercells. In a slower scenario, it`s possible the greatest coverage of mid-evening supercells stays south and east of the area. And as usual, storm-scale interactions will play a role in the coverage and severity of convection, and this is tough to pin down before storms develop, let alone 24+ hours out. Regardless, given the higher end potential of these storms and their occurrence on a holiday weekend, keeping up to date with the latest forecast information will be important. The surface low continues east on Sunday, pushing the better combination of instability and shear east of our area. We still may a few storms capable of large hail Sunday afternoon across eastern Kansas. Lingering moisture behind the low and cool temperatures aloft keep instability around. By Memorial Day, we look to quiet down as the upper low moves further east and surface high pressure approaches. A few brief shower and thunderstorms chances will still be possible through mid-week with weak shortwaves in northwest flow aloft, but overall the pattern will be much drier. Temperatures look to stay near or slightly below average, with highs near 80 and lows in the 50s. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 641 PM CDT Fri May 24 2024 NW winds early will turn light and variable overnight, if not completely calm with high pressure overhead. This in addition to clear skies may lead to some patchy, shallow ground fog in river valleys around sunrise, which would mainly impact KTOP, but still confidence was not high enough to include in TAF. Winds should then pick up from the SSE during the daytime Saturday. Will need to watch for storm chances increasing Saturday evening, although the most likely time looks to be after this forecast period. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Reese AVIATION...Picha