textproduct: Topeka

KEY MESSAGES

- Scattered storms are expected to develop along a dryline/cold front across north-central late this afternoon and into the evening. Localized flooding, large hail (up to 2.5 inches) and damaging winds (60-70 mph) will be possible.

- Widespread severe thunderstorms are still expected Monday afternoon and evening across eastern Kansas. Storms are expected to be rather intense with all modes of severe weather possible (hail up to 2-4", damaging winds to 70-80 mph, and a few tornadoes - some strong).

- A Flood Watch has been issued for areas north of I-70 through Tuesday morning. Heavy rainfall from several rounds of thunderstorms could yield in 2-4 inches of rainfall with locally higher amounts.

- Storms exit the area by early Tuesday morning with a much cooler air mass moving into the region for the remainder of the week. Shower and storm chances return Thursday-Saturday to the region.

DISCUSSION

Issued at 327 PM CDT Sun May 17 2026

Another volatile environment is setting up for strong thunderstorms this afternoon across the central Plains just ahead of a deepening, posititevely-tilted upper trough in the Rockies. Persistent PVA into the central Plains has further deepened a 995 mb surface low across northwestern Kansas with a tight pressure gradient extending to its east across Kansas. Gusty winds and strong low-level moisture transport have become apparent this afternoon over eastern Kansas as mixing and diurnal heating has slowly mixed out cloud cover. By the later afternoon hours, diurnal heating and low-level moisture transport will push MLCAPE values into the 3000-3500 J/kg range with modest deep shear. Initial storm development can be expected to develop near the triple point region in north-central Kansas and along the dryline to the south across central Kansas in the 6-7 PM timeframe. Storms will likely strengthen quickly given the steep ML and LL lapse rates. Initial threats with storms will be very large hail (up to 2-3 inches in diameter) and winds up to 60-70 mph. By the early evening, a 0-1 km bulk shear vectors and slight backing of surface winds will help to elongate hodographs across the the warm sector and help to increase the tornado threat within storms. That said, the lack of deep shear this far east of the main upper-level wave seems to be modest at best (20-35 knots). This indicates the potently for storms to lack the structure to maintain themselves for long periods. Better shear values for long and sustained supercells seems to stay north and west of the area this evening. Taking all of this into account, the best window for strong to severe storms seems to be from 6PM to midnight tonight. Elevated convection will track east through the overnight hours aided by outflow boundaries and isentropic ascent within the LLJ. As most convection will remain elevated after 12 AM tonight, main hazards will be large hail and an occasional wind gust to 50-60 mph. Training and backbuilding of convection in the early morning hours of Monday may also pose a localized flooding concern with areas picking up a quick 1-2 inches with locally higher amounts to 3-4 inches remaining a possibility.

Attention quickly turns to Monday as this appears to be the day that will pose the most widespread and high-end risk for severe weather. Lingering rain and thunderstorms will exit into Missouri by the mid morning Monday leaving much of far eastern Kansas blanketed with stratus. There have been hints that an outflow boundary will remain across the area from morning convection. This could become a focal point in convection later in the afternoon so will need to monitor this as convection exits in the morning. Through the day, the long wave trough that has remained stalled over the central Rockies ejects over the central Plains, taking on a negative tilt across Kansas. Low-level mesoscale features will respond to the upper trough's eastward push with a surface cyclone entering central and north-central KS by peak heating hours. Ahead of the surface low, a very unstable warm sector characterized by upper 60 degree Tds, upper 80 and low 90 degree surface Ts will be in place. Aloft, a 50- 60 knot 500 mb jet will overspread central and eastern Kansas with cooling mid-level temperatures and intense divergence aloft. This will push MLCAPE values into the 4000-4500 J/kg. RAP and HRRR analysis has MLCIN and SBCIN eroding by 18-20z in central and north- central Kansas, just ahead of the surface triple point. Convective initiation along the dryline/coldfront in the 20-22z timeframe has been noted by HREF analysis. There is a small chance that isolated cells go up ahead of the frontal boundary, especially if there is an outflow boundary stalled out over the region, but confidence in this occurring is low at the moment. Not much has changed in terms of overall threats as we are still looking at very large hail (up to 2- 4" in size), damaging winds (70-80 mph) and tornadoes, some possibly strong.

The main question at this point in time is the overall evolution in storms Monday evening. If storms can move off the boundary and become isolated, this would pose a greater risk for strong tornadoes, and very large hail. The other scenario would be for storms to form along the boundary and grow upscale. While storms will still be very intense in the upscale scenario, storm interactions may limit the intensity of storms a bit keeping large hail, damaging winds and a few tornadoes possible. Given lots of curvature in low-level hodographs in the warm sector, it seems likely that several well-established supercells will separate from the front and follow the right vector that takes the storm more east/northeast rather than northeast. These storms will be the most intense, especially if they remain isolated with little storm interferences. The area best suited for these storms to impact seems to be from north-central KS into the Flint hills. Once storms reach far eastern Kansas, outflow boundaries and storms interactions seem to increase and congeal most remaining convection into a line of embedded supercells. This would transition the treat to isolated, embedded tornadoes within the line, straight line winds and large hail.

Severe storms should exit with the front by Tuesday morning, returning dry and well below normal temperatures to the region Tuesday afternoon. A much cooler air mass moves in for the remainder of the week with rain and storm chances by Thursday and Friday with some long wave troughs entering the central US.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 557 PM CDT Sun May 17 2026

CAMs continue to show a decaying MCS impacting the terminals through the late evening. Have tried to time precip and winds from the HRRR/consensus of CAMs. MVFR CIGS and IFR VSBY are expected to occur with the precip and models show the MVFR CIGS lingering well into the late morning Monday. Eventually CIGS should improve to VFR with south winds strengthening.

CLIMATE

Issued at 336 AM CDT Sun May 17 2026

Record High Temperature

Sunday May 17 Record (Year) Forecast Topeka 92 (1907) 90 Concordia 96 (1996) 97

Monday May 18 Record (Year) Forecast Topeka 94 (1975) 91 Concordia 94 (1967, 1988) 89

Record Warm Low Temperature

Sunday May 17 Record (Year) Forecast Topeka 73 (1996) 69 Concordia 68 (1902, 1906) 67

Monday May 18 Record (Year) Forecast Topeka 71 (1911) 70 Concordia 72 (1911) 64

TOP WATCHES/WARNINGS/ADVISORIES

Wind Advisory until 9 PM CDT this evening for KSZ008-KSZ009-KSZ010- KSZ011-KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024-KSZ034-KSZ035- KSZ036-KSZ037-KSZ038-KSZ039-KSZ054-KSZ055-KSZ058. Flood Watch through Tuesday morning for KSZ008-KSZ009-KSZ010-KSZ011- KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024-KSZ034. Wind Advisory from 9 AM to 9 PM CDT Monday for KSZ035-KSZ036-KSZ037- KSZ038-KSZ054.