Thunderstorms developed across portions of central and northern Kansas during the late afternoon hours of August 21st. Upon reaching the Interstate 70 corridor, the thunderstorm complex greatly slowed its southern progression, causing several hours of heavy rainfall.
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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.
Thunderstorms developed across portions of central and northern Kansas during the late afternoon hours of August 21st. Upon reaching the Interstate 70 corridor, the thunderstorm complex greatly slowed its southern progression, causing several hours of heavy rainfall. Some areas in southern Douglas and northern Franklin received as much as 9 inches of rainfall.
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 Aug 21, 5:42 PM CST, 1 hour 35 minutes earlier.
Area Forecast Discussion National Weather Service Topeka KS 642 PM CDT Mon Aug 21 2017 ...Update to aviation forecast discussion... .SHORT TERM...(This evening through Tuesday) Issued at 257 PM CDT Mon Aug 21 2017 19Z water vapor imagery shows a low amplitude shortwave moving through the northern plains. A weak MCV from the early morning convection has become difficult to discern over northeast KS and likely has sheared out. Otherwise water vapor imagery shows a plume of mid level moisture from wester TX through northeast KS. At the surface, a prefrontal trough was noted from northwest KS into the eastern Dakotas with a cold front over western ND and into eastern WY. For tonight models still show some weak vorticity advection ahead of the northern plains shortwave and some frontogenesis overnight with the front. With the very moist airmass in place, showers and thunderstorms are expected to become widespread this evening and move through the area overnight. Models have trended slightly faster with the frontal system and some of the high resolution models show precip exiting the forecast area to the southeast by 7 am Tuesday. The clouds and shower activity have slowed down the destabilization of the boundary layer. But RAP analysis suggests MLCAPE values over 2000 J/kg beginning to develop. Deep layer shear remains a little marginal, but look to be good enough that if a discrete storm were able to persist it could go on to produce some severe hail and winds. Aside from that, the main focus remains on the heavy rain potential. With PWs still progged over 2 inches, the airmass looked primed for heavy rainfall. Although with the model trends of a faster progression to the frontal system, the risk for flash flooding looks to have diminished somewhat. While the ensemble means for QPF have also lessened, a few members continue to show the potential for isolated heavy to excessive rain. Because of this will maintain the flash flood watch as is. Showers and thunderstorms should be moving southeast of the area Tuesday morning and have POPs decreasing with virtually a dry forecast for much of the area by noon. The stronger cold air advection looks to hold off until late morning or early afternoon so Lows tonight are expected to remain muggy with readings in the upper 60s to around 70. Have trended highs cooler by a degree or two with models showing decent low level cold air advection through the afternoon. Have forecast highs in the lower and middle 80s. .LONG TERM...(Tuesday night through Monday) Issued at 257 PM CDT Mon Aug 21 2017 By Tuesday night, the mid-level trough will be shifting into the northeastern U.S. with surface high pressure sliding southward from the Northern Plains into the central U.S. The region will remain under the influence of this surface high pressure and northwesterly flow aloft through Thursday, resulting in dry conditions and temperatures cooler than the seasonal normals with highs in the low 80s. By Thursday night, models show a mid-level ridge briefly building into the central U.S. ahead of a mid-level trough diving into the Pacific Northwest. Models are in decent agreement with showing an embedded shortwave developing within this ridge Thursday night and gradually tracking across the CWA Friday and Friday night. The mid- level trough over the Pacific Northwest will get pushed back into Canada as a broad mid-level ridge builds across the western U.S. Saturday through Monday. The central U.S. will remain under northwesterly flow aloft into early next week, with models showing additional embedded waves developing within the mid-level flow. As a result, some periods of scattered showers and thunderstorms will be possible from Thursday night into Sunday, with some isolated precipitation possibly continuing into early next week. Temperatures through the weekend and into early next week will remain below the seasonal normals, with highs staying in the low 80s and low temperatures in the low 60s. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 610 PM CDT Mon Aug 21 2017 Scattered TSRA developing north and west of terminals currently. Radar trends has the cluster through KMHK by 02Z with no reduction in flight category. A little more uncertain how the band of TSRA evolves as it moves eastward towards KTOP/KFOE. Sfc analysis shows a frontal boundary in the area with ample instability, despite meager amounts of wind shear. Have therefore kept a mentioned of VCTS with scattered showers through 08Z when short term models clear the convection eastward. Next focus is the convection that develops along the front currently in Nebraska in the 06-09Z time frame. Current indications is that coverage may not be as widespread as previous guidance. Nonetheless kept the mention of TSRA with MVFR stratus developing along and just behind the boundary through 16Z. && .TOP WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Tuesday morning for KSZ011-012-022>024- 026-035>040-054>056-058-059. && SHORT TERM...Wolters LONG TERM...Hennecke AVIATION...Prieto
Hazardous Weather Outlook National Weather Service Topeka KS 307 PM CDT Mon Aug 21 2017 KSZ008>012-020>024-026-034>040-054>056-058-059-222015- Republic-Washington-Marshall-Nemaha-Brown-Cloud-Clay-Riley- Pottawatomie-Jackson-Jefferson-Ottawa-Dickinson-Geary-Morris- Wabaunsee-Shawnee-Douglas-Lyon-Osage-Franklin-Coffey-Anderson- 307 PM CDT Mon Aug 21 2017 This hazardous weather outlook is for east central...north central and northeast Kansas. .DAY ONE...This Afternoon and tonight. Thunderstorms are forecast to become widespread this evening and move southeast across the region. As storms develop, there is a risk for some large hail and strong winds. However storms should develop into a large cluster with locally heavy rainfall becoming the primary concern. Some isolated spots could end up with around 2 inches of rain by Tuesday morning. Because of this a flash flood watch remains in effect for areas along and east of a line from Abilene to Seneca. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters should not be needed this afternoon or tonight, but are encouraged to report rainfall amounts and any flooding. && More detailed information can be accessed at... http://www.weather.gov/top/sitrep Wolters
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TOPEKA KS
734 PM CDT MON AUG 21 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0733 PM HEAVY RAIN NORTONVILLE 39.41N 95.33W
08/21/2017 E2.25 INCH JEFFERSON KS CO-OP OBSERVER
STORM TOTAL THUS FAR. STILL REPORTING HEAVY
RAIN IN NORTONVILLE.
&&
JPSpecial Weather Statement
National Weather Service Topeka KS
749 PM CDT MON AUG 21 2017
KSZ011-012-024-220115-
Brown-Jackson-Nemaha-
749 PM CDT MON AUG 21 2017
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN NEMAHA...CENTRAL
JACKSON AND SOUTHWESTERN BROWN COUNTIES UNTIL 815 PM CDT...
At 748 PM CDT, Doppler radar was tracking a strong thunderstorm over
Soldier, moving east at 35 mph.
Wind gusts up to 50 mph will be possible with this storm.
Locations impacted include...
Holton, Horton, Wetmore, Whiting, Denison, Circleville, Netawaka,
Soldier, Goff and Kickapoo Reservation.
LAT...LON 3973 9552 3965 9552 3965 9556 3942 9557
3942 9559 3936 9559 3939 9603 3947 9604
3967 9598
TIME...MOT...LOC 0048Z 264DEG 29KT 3953 9593
27Special Weather Statement
National Weather Service Topeka KS
759 PM CDT MON AUG 21 2017
KSZ024-038-039-220130-
Wabaunsee-Shawnee-Jackson-
759 PM CDT MON AUG 21 2017
...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN SHAWNEE...NORTHEASTERN
WABAUNSEE AND SOUTHERN JACKSON COUNTIES UNTIL 830 PM CDT...
At 759 PM CDT, Doppler radar was tracking a strong thunderstorm over
Rossville, moving east at 40 mph.
Wind gusts up to 50 mph will be possible with this storm.
Locations impacted include...
Northern Topeka, Rossville, Silver Lake, Hoyt, Maple Hill, Mayetta,
Delia and Willard.
This includes Interstate 70 between mile markers 342 and 349.
LAT...LON 3911 9560 3903 9602 3914 9605 3913 9604
3917 9606 3917 9605 3916 9604 3924 9603
3939 9572 3919 9559
TIME...MOT...LOC 0059Z 250DEG 34KT 3916 9594
27Special Weather Statement
National Weather Service Topeka KS
812 PM CDT MON AUG 21 2017
KSZ038-054-220145-
Wabaunsee-Lyon-
812 PM CDT MON AUG 21 2017
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN WABAUNSEE AND
NORTHEASTERN LYON COUNTIES UNTIL 845 PM CDT...
At 812 PM CDT, Doppler radar was tracking a strong thunderstorm near
Allen, moving northeast at 35 mph.
Wind gusts up to 50 mph will be possible with this storm.
Locations impacted include...
Harveyville, Allen and Admire.
This includes Kansas Turnpike between mile markers 148 and 154.
LAT...LON 3874 9630 3892 9598 3883 9594 3867 9595
3862 9620
TIME...MOT...LOC 0112Z 239DEG 29KT 3869 9621
27The Topeka radar (KTWX), 53 km away, was scanning. The volume nearest the first event began at 01:19 UTC.
11 flash flood, 9 thunderstorm wind. Local standard time, as filed.
Delayed report of an ornamental tree, 10 inches in diameter was down on a neighbors house. Several 2-2.5 inch diameter limbs were down as well. Time was estimated from radar.
Two inch diameter tree limb was down.
Estimated wind gust report.
Ditches are overflowing, water over roadways 2 miles east of Nortonville and in fields near house. Estimated rainfall of 4.82 inches.
Reports of several 2 inch diameter limbs down.
Report via social media picture. 10 inch diameter tree branch split from the main trunk. Radar estimated time.
Six inch diameter tree limb down.
Delayed report of tree split in half. Time was estimated via social media.
Emergency manager relayed reports strong winds of 60 mph at Peterson and Kasold Ave.
Report of 10 inches of standing water at 10th and Topeka due to flash flooding.
Numerous trees were reported to be split along with several tree branches snapped. The sizes were unknown. Delayed report. Time was based on radar.
Swift water rescue was ongoing due to flash flooding.
Flash flooding of several streets in Wellsville.
Delayed report of a water rescue.
Delayed report of a water rescue.
Numerous low water crossings were under water.
Northwest Hodges Road from 35th Street to Highway 24 is approximately 2 feet under water.
Several rural roads are under water in the northeast portion of Franklin County. 2 water rescues from vehicles and 1 from a home.
N400 road was washed out due to flash flooding. The town of Lone Star was reported flooded. Many county roads flooded in low lying areas.
Water rescue reported in the 3800 block of Nebraska Drive in Ottawa.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Kansas in 2017Every state in 2017This day in weather historyWarnings in Kansas, August 2017
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: 720212, 720214, 720215, 720216, 720217, 720218, 720219, 720220, 720221, 720235, 720222, 720231, 720223, 720224, 720225, 720226, 720227, 720228, 720229, 720232.