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FXUS63 KTOP 272155 AFDTOP

Area Forecast Discussion National Weather Service Topeka KS 455 PM CDT Sat Apr 27 2024

KEY MESSAGES

- Severe thunderstorms will the risk of all hazard types remain possible in the Tornado Watch area until 7pm. Additional storms may develop later this evening, especially across north central Kansas.

- A few strong storms could develop again Sunday in eastern KS as a front continues to move through the area.

- Active pattern continues through next week with several more chances for showers and thunderstorms.

UPDATE
Issued at 451 PM CDT Sat Apr 27 2024

Cancelled most of the Tornado Watch as the environment has become more stable and further development is not anticipated over the next several hours. As the low-level jet increases tonight and upper-level ascent from the low pressure system currently over far southwest Kansas begins to push eastward, additional storms may develop along the warm front later this evening.

Additionally, a High Wind Warning has been issued for 60-80 mph winds associated with a wake low across Riley, Pottawatomie and Wabaunsee Counties. Several semi trucks have been blown over on highways.

DISCUSSION
Issued at 412 PM CDT Sat Apr 27 2024

Mid-level trough has been moving through the Four Corners region throughout the day. Associated sfc warm front has been slowly pushing north across the forecast area, and is near the KS/NE border as of 20Z. The dryline appears to be well southwest of the area, although this has been obscured by the ongoing convection in northern OK and south central KS moving northward into east central KS. Our initial round of storms early this afternoon developed along the warm front, and a wake low developed in southwest portions of the area helping to push the boundary north. The outflow from this initial activity has led to a substantial decrease in instability across most of the area, with the exception of our far eastern counties where there is still upwards of 3000 J/kg of CAPE. Any additional severe storms at this point would need to be able to move into those areas out of the cluster of storms coming from OK. The CAMs are still suggesting repeated rounds of storms with heavy rainfall to move through much of eastern KS this evening and overnight, with another batch developing toward central KS towards 06-07Z. It is also around this time that Pwat approaches or exceeds 1.5", especially in east central KS. Decided to add Geary, Riley, and Marshall Counties to the Flood Watch factoring in the initial round of storms today plus recent trends in the CAMs, suggesting those areas could see more locally heavy rain through the overnight hours. Still have highest confidence in east central locations, however.

Heading into Sunday, the upper low is still progged to be in NE/SD with the sfc low progressing northeastward through KS/NE. While parameters don't look nearly as high as they did for today, instability and shear would again be supportive for severe weather for any storms that develop in eastern KS ahead of the cold front.
Will need to also monitor how well the atmosphere is able to recover following the overnight convection after it moves out, but forecast soundings at TOP currently suggest capping should erode by 18-19Z.
Any storms that develop should move out of the area through the evening.

Monday looks to be the one dry day in the upcoming week before an active pattern commences once again. Broad upper troughing is progged to develop across much of the northwestern CONUS and deepen over the western US by mid-week. Multiple perturbations within that flow aloft lead to chances for showers and thunderstorms Tuesday onward during the work week. Timing and placement of any of these storms are uncertain this far out.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
Issued at 1250 PM CDT Sat Apr 27 2024

Main aviation concern is with thunderstorms in the first half of the period, which have the potential to be severe. Storms have already developed along a line from Salina to Sabetha near the warm front. These may stay just north of the MHK terminal initially, but with additional storms expected to move in from south central KS and more development possible in the warm sector, have gone ahead with a tempo TSRA at MHK for a few hours this afternoon. Otherwise, storms should continue to move east toward the Topeka terminals later this afternoon into the evening, although guidance remains mixed on exactly when and how quickly they move into east central KS. With this in mind, amendments will need to be made as necessary. It's tough to pinpoint any point in time when there could be any breaks in convection through the evening and overnight, though there should be an end to the activity by early morning. MVFR cigs look to make a return late tonight, likely not scattering until after this period.

TOP WATCHES/WARNINGS/ADVISORIES
Flood Watch through Sunday morning for KSZ010-KSZ011-KSZ012- KSZ022-KSZ023-KSZ024-KSZ026-KSZ036-KSZ037-KSZ038-KSZ039-KSZ040- KSZ054-KSZ055-KSZ056-KSZ058-KSZ059.
High Wind Warning until 7 PM CDT this evening for KSZ022- KSZ023-KSZ038.

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