Flash Flood and Hail in Kansas, May 17, 2026

Area Forecast Discussion
National Weather Service Topeka KS
557 PM CDT Sun May 17 2026

.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.

&&

DISCUSSION...Griesemer
AVIATION...Wolters
CLIMATE...Griesemer

Hazardous Weather Outlook
National Weather Service Topeka KS
326 PM CDT Sun May 17 2026

KSZ008>012-020>024-026-034>040-054>056-058-059-182030-
Republic-Washington-Marshall-Nemaha-Brown-Cloud-Clay-Riley-
Pottawatomie-Jackson-Jefferson-Ottawa-Dickinson-Geary-Morris-
Wabaunsee-Shawnee-Douglas-Lyon-Osage-Franklin-Coffey-Anderson-
326 PM CDT Sun May 17 2026

This Hazardous Weather Outlook is for portions of central Kansas,
east central Kansas, north central Kansas, and northeast Kansas.

.DAY ONE...This Afternoon and Tonight

Gusty south winds from 20 to 30 mph with gusts up to 45 mph
through early evening.

Scattered severe storms are possible after 5 PM across north central
Kansas. These storms may form into a line as they move east southeast
this evening. Very large hail, damaging wind gusts, and a few
tornadoes are the main hazards. Localized flooding is also a
concern if storms train over areas that received heavy rain the
previous evening.

A Flood Watch remains in effect from 7 PM this evening through 7
AM Tuesday morning for areas along and north of I-70. Widespread
rainfall totals of 2-4 inches are expected with locally higher
amounts could lead to flooding.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Gusty south winds return across the Flint Hills Monday morning and
afternoon with sustained winds of 20-30 mph and gusts upwards of
45 mph into the early evening. A Wind Advisory remains in effect
for Dickinson, Morris, Lyon, Geary and Wabaunsee counties from 9
AM to 9 PM Monday.

The greatest chance for severe weather is still shaping up to be
Monday afternoon and Monday night. There is good confidence in
storms developing over north central KS by the early evening and
move across all of northeast and east-central Kansas through the
night. Storms will be capable of producing tornadoes, very large
hail, damaging winds and flash flooding. People should be prepared
for thunderstorms impacting the area.

A Flood Watch remains in effect from 7 PM this evening through 7
AM Tuesday morning for areas along and north of I-70. Widespread
rainfall totals of 2-4 inches are expected with locally higher
amounts could lead to flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.