Several rounds of thunderstorms along a stationary frontal boundary resulted in significant flash-flooding in portions of Riley, Marshall, and Pottawatomie Counties. Numerous damaging wind reports were noted as well.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS TOP wrote it up.
Several rounds of thunderstorms along a stationary frontal boundary resulted in significant flash-flooding in portions of Riley, Marshall, and Pottawatomie Counties. Numerous damaging wind reports were noted as well.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Topeka, KS wrote its last area forecast discussion before the first event at Sep 2, 2:14 PM CST, 2 hours earlier.
Area Forecast Discussion National Weather Service Topeka KS 314 PM CDT Sun Sep 2 2018 .SHORT TERM...(This evening through Monday) Issued at 247 PM CDT Sun Sep 2 2018 Water vapor imagery shows a shortwave across west central KS with another wave moving toward KS out of eastern NM. 850mb VWP network shows rather uniform SSE flow of 15-20 kts at this time across the region with the 850mb front across central NE. Sfc map shows a low across southwest KS with a diffuse boundary extending ENE into northern KS. Vis satellite imagery also shows what appears to be an elevated boundary that extends south into north TX. this boundary is acting as a focus for convection at the moment from near TOP south toward ICT. For tonight...main concern is excessive rains and potential flooding. Expect convection to develop across west/central KS near RSL/Hays toward SLN through early evening. Effective shear of 35-45 kts may allow for early discrete cell/supercell characteristics however hodographs become messy in the mid-levels so evolution into multicell clusters appears likely or short line segments as the evening wears on. Main severe risk would appear to be downburst winds through the evening with some hail risk across the western counties. Poor mid-level lapse rates should temper any greater hail risk however. Tornado threat is non zero but appears to be limited to areas across our far west/sw counties for a time late this afternoon or early evening but even this appears conditional on storm evolution. Greater concern is flooding given overall mesoscale and synoptic set up. PWATs approaching 2" combined with a modest but present 25-35kt LLJ and a source of MUCAPE of 1-2k overnight will exist in region of upper divergence in right entrance region of upper jet. Evolution of convection into a cluster or line appears likely and storm motion/corfidi vectors suggest ENE movement however thetae ridge will remain anchored across central KS so backbuilding appears likely too so could see training. HREF ensemble precip matched mean clusters max precip across central KS where amounts in excess of 3" appears likely. Much uncertainly still exist however in the exact placement of the cluster overnight especially in how far south and east any of the heaviest rains could fall. At the moment we do not anticipate major changes to the flood watch area for tonight but those near the flood watch area including the Topeka area need to stay aware of trends tonight. .LONG TERM...(Monday night through Sunday) Issued at 247 PM CDT Sun Sep 2 2018 BOTTOM LINE UP FRONT, The very wet pattern will continue through the week with chances for t-storms and locally heavy rains forecast to persist through Friday and perhaps into Saturday. Another wave will move across the area Monday night into Tues with more heavy rains and by Weds the 850mb front will drop into the area which will serve as a focus for heavy rains into late week. The atmosphere will remain very moist with PWATS well above climo avg likely around 2". && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) Issued at 1132 AM CDT Sun Sep 2 2018 T-storm coverage should increase this evening with best chances through 6Z expected to to around MHK where we have attempted to place more timing detail into MVFR/IFR VIS conds due to tsra. Bottom line showers and t-storms will increase in coverage through the period with widespread rain/tsra expected to push conds into the MVFR with periods of IFR possible due to tsra overnight. Still not certain about timing for TOP/FOE for worst conds so have opted to keep IFR mention out for now. && .TOP WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Monday morning for KSZ008>012-020>024- 034>036. && SHORT TERM...Omitt LONG TERM...Omitt AVIATION...Omitt
Hazardous Weather Outlook...UPDATED National Weather Service Topeka KS 335 PM CDT Sun Sep 2 2018 KSZ008>012-020>024-026-034>040-054>056-058-059-032045- Republic-Washington-Marshall-Nemaha-Brown-Cloud-Clay-Riley- Pottawatomie-Jackson-Jefferson-Ottawa-Dickinson-Geary-Morris- Wabaunsee-Shawnee-Douglas-Lyon-Osage-Franklin-Coffey-Anderson- 335 PM CDT Sun Sep 2 2018 This hazardous weather outlook is for east central...north central and northeast Kansas. .DAY ONE...This Afternoon and tonight. Thunderstorms are expected this afternoon through tonight. A few of the storms may be severe with damaging winds the main hazard in the late afternoon and evening hours. An isolated tornado may also be possible early this evening as would a low risk for large hail but this risk appears to be limited to areas west of a Junction City to Marysville line early this evening. The greater concern is widespread heavy rainfall overnight across central and parts of northeast Kansas where a Flash Flood Watch is posted. Rainfall amounts in excess of 3 inches are possible. This may cause flash flooding so remember don't drive through flooded roads! .DAYS TWO THROUGH SEVEN...Monday through Saturday. Thunderstorm chances persist into Monday with periods of heavy rainfall being possible during the day. An active weather pattern brings continued chances for thunderstorms through much of the upcoming week so the risk for flooding could persist through the week. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed through sunset mainly west of a Junction City to Marysville line. Rainfall reports are also encouraged overnight and especially Monday morning. && More detailed information can be accessed at... http://www.weather.gov/top/sitrep
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TOPEKA KS
1228 PM CDT SUN SEP 2 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1227 PM HEAVY RAIN 1 NW REPUBLIC 39.93N 97.83W
09/02/2018 M2.69 INCH REPUBLIC KS COCORAHS
RAINFALL TOTAL AS OF 12 PM.
&&Special Weather Statement National Weather Service Topeka KS 419 PM CDT SUN SEP 2 2018 KSZ034-022145- Ottawa- 419 PM CDT SUN SEP 2 2018 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN OTTAWA COUNTY UNTIL 445 PM CDT... At 419 PM CDT, Doppler radar was tracking a strong thunderstorm near Culver, moving northeast at 15 mph. Half inch hail and wind gusts up to 50 mph will be possible with this storm. Locations impacted include... Bennington and Culver. PRECAUTIONARY/PREPAREDNESS ACTIONS... Torrential rainfall is also occurring with this storm, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 3909 9762 3896 9757 3896 9787 3900 9788 TIME...MOT...LOC 2119Z 215DEG 14KT 3896 9779 Cohen
The Topeka radar (KTWX), 124 km away, was scanning. The volume nearest the first event began at 22:14 UTC.
11 flash flood, 5 thunderstorm wind. Local standard time, as filed.
Wind gusts estimated between 60 and 70 MPH. Very heavy rainfall also reported.
Estimated wind speeds of 60 MPH.
Estimated wind gust of 60 MPH.
Tree limbs 2-3 inches in diameter were reported down.
Water was flowing over numerous roads in Marysville.
Estimated wind gust of 60 MPH. Tree limbs were reported down although the size was unknown.
Highway 77 had up to a foot of water flowing across the road.
Numerous roadways were under water, including the intersections at K-18/90th road and Mulberry road/60th road.
Highway 77 near Osage Road is closed due to high water. Estimated 10-12 inches of running water across the road. A water rescue occurred.
Delayed report of running water over roads in and near Fancy Creek State Park.
A bridge was washed out near the intersection of East River Road and Osage Road.
High water caused a mudslide that covered the roadway, making it impassable on Blue River Road.
Residents in the city of Keats were being evacuated due to the rapidly rising water on Wildcat Creek. The flooding of Wildcat creek resulted in an estimated 17.2 million dollars in losses to property.
Multiple roads were impassable due to high water overflowing the road.
Road closure on Fort Riley Boulevard from Westwood to Richards due to water over the bridge.
Roadway closed due to water across the road approximately 8 miles west of Concordia.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Kansas in 2018Every state in 2018This day in weather historyWarnings in Kansas, September 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 786186, 786187, 786188, 786189, 786190, 786191, 786192, 786193, 786195, 786196, 786197, 786198, 786199, 786200, 786201, 786203.