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FXUS63 KTOP 261121 AFDTOP

Area Forecast Discussion National Weather Service Topeka KS 621 AM CDT Fri Apr 26 2024

KEY MESSAGES

-Two separate storm systems bring several rounds of thunderstorms to the area through the weekend.

-Large hail, strong damaging winds and tornadoes are all possible this afternoon in far eastern KS, and again Saturday.

-Multiple rounds of rain could also lead to localized flooding.

DISCUSSION
Issued at 404 AM CDT Fri Apr 26 2024

Early this morning, a 50 kt LLJ is in place over eastern KS ahead of a deepening mid-level storm system that is ejecting out over the High Plains of Nebraska/Kansas. The surface low is over far western KS with a warm front extending east/southeast through southern KS. Dew points south of the warm front are in the mid to upper 60s. The warm sector of the system will continue to advance northward through the area this morning as the warm front passes to the north. Instability will build to over 2500 J/kg of SBCAPE with steep mid-level lapse rates between 7-7.5 C/km in place across eastern KS by mid-afternoon.
Strong wind fields east of the upper low will lead to sufficient deep layer shear for severe weather, while 0-3km SRH values ranging from 150-200 m2/s2 point to a tornadic potential.
Thus, all modes of severe weather will be possible with any supercell development east of the dryline this afternoon. Some CAMs hint at isolated to widely scattered convective initiation as early as 20Z, with storms exiting to the east by around 01Z.

A period of dry weather is expected tonight as the first system moves northeast into the Upper Midwest. In the meantime, a second system will dig over the desert southwest, inducing surface cyclogenesis in southwest KS. Central and eastern KS will remain in the warm sector with a surface boundary northwest of the area. The setup Saturday still appears to have better potential for a round of significant and widespread severe weather impacting the area. HRRR shows average SBCAPE in excess of 3000 J/kg and 0-3km SRH between 100 and 200 m2/s2. A complex of storms looks to develop south of the area during the afternoon and move northward as the upper level jet and large scale forcing increases. Once again, given the impressive shear and instability parameters, all modes of severe weather (very large hail, damaging wind and tornadoes) will be possible. Heavy rainfall could also occur, leading to localized flooding, especially where grounds were recently saturated by heavy rain from Anderson County northwest through Cloud County.
The convective complex looks to slowly work eastward with time, while continuing into the overnight period.

Yet another round of severe weather looks possible Sunday afternoon in eastern portions of KS with the main trough axis and surface cold front still just west of the area. A little more uncertainty exists with this round, which will be partially dependent on how much destabilization can occur following previous heavy thunderstorm activity and lingering cloud cover. Some models, however, show enough deep layer shear to support rotating updrafts with any storms that manage to develop before the front pushes through the area Sunday night.

Following these several rounds of active and potentially impactful weather, a much needed stretch of quite weather is then anticipated to begin the next workweek. NBM has POPs increasing once again by midweek when our next cold front could approach the region.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
Issued at 618 AM CDT Fri Apr 26 2024

Isolated showers could occur this morning before a period of dry weather is expected through midday. IFR ceilings should gradually lift through the morning and become VFR by early afternoon. Strong southerly winds will gust to over 30 kts at times this afternoon. Then, a few storms could develop after 20Z near the Topeka airports. Coverage looks to be isolated or widely scattered, so have not included TS in TAFs. If storms develop, large hail, damaging wind and a few tornadoes could occur.

TOP WATCHES/WARNINGS/ADVISORIES
None.

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