During the afternoon hours of the 28th supercell thunderstorms developed over southwest Iowa causing two confirmed tornadoes and reports of large hail. These storms formed in response to a slow-moving cold front that passed through the region during the afternoon and early evening hours.
Every event with a place to put it. Tap one for its entry below.
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 OAX wrote it up.
During the afternoon hours of the 28th supercell thunderstorms developed over southwest Iowa causing two confirmed tornadoes and reports of large hail. These storms formed in response to a slow-moving cold front that passed through the region during the afternoon and early evening hours.
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 Omaha, NE wrote its last area forecast discussion before the first event at Jun 28, 12:28 PM CST, 2 hours 18 minutes earlier.
Area Forecast Discussion National Weather Service Omaha/Valley NE 128 PM CDT Wed Jun 28 2017 .SHORT TERM...(Today through Friday) Issued at 351 AM CDT Wed Jun 28 2017 Today...increasing low level theta-E advection is progged to persist through this afternoon with moisture pooling along stalled boundary layer moisture convergence zone setting up from about central IA to western KS. RAP13 is showing mixing ratios increasing to 17g/kg...PWS 1.75" by late afternoon over the southern CWA. And coupled with daytime heating...instability parameters will quickly ramp up particularly along/south of I-80. Expect storms to fire initially over the southern portion of the IA CWA before expanding swwd over the rest of the southern CWA. The environment at that time will be quite capable of supporting supercells through early evening given Sfc-6km shear exceeding 60kt...effective bulk shear 40-45kt. As of now...besides large hail/damaging wind threat...definitely appears to be a risk for tornados particularly over the southern portion of the IA CWA where stout Sfc-1km helicity phases well with MLCAPE of 3000J/kg and low LCLs. Focus for convective activity the rest of the overnight hours will remain over the southern CWA. Thursday/Thursday night....NAM/GFS/ECM in agreement showing the stalled boundary slowly lifting across the CWA before washing out in the early evening before a cold front...associated with surface low pressure lifting into the upper Midwest...sweeps sewd into the central Plains. HiRes ARW/NMM both advertise convection firing along the boundary by mid afternoon from southeast SD to southwest Neb with activity eventually moving through the CWA during the late afternoon/early evening hours. Steep mid level lapse rates atop plentiful boundary layer moisture would suggest hail producing storms are probable early on before convection organizes into linear mode and migrates southward. Friday/Friday night...dry conditions as relatively stable airmass filters in from the north. .LONG TERM...(Friday night through Tuesday) Issued at 351 AM CDT Wed Jun 28 2017 Precip chances continue through the majority of the extended period...particularly Sunday through Monday night in association with a Pacific NW disturbance moving into the central Plains. Otherwise...near normal max temps expected Sunday through Tuesday with above normal highs coming on Wednesday. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) Issued at 121 PM CDT Wed Jun 28 2017 VFR ceilings and visibilities are forecast at KOFK, KOMA, and KLNK. Surface cold front extending from western MN to south central Nebraska at 17Z will move southeast during the forecast period. Thunderstorms are forecast after 21Z along and south of the front. VCTS was added to the KOMA and KLNK TAFS after 23Z. Winds will shift after cold front passage to the northwest. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && SHORT TERM...DEE LONG TERM...DEE AVIATION...Smith
Hazardous Weather Outlook National Weather Service Omaha/Valley NE 1201 PM CDT Wed Jun 28 2017 IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034- 042>045-050>053-065>068-078-088>093-290715- Monona-Harrison-Shelby-Pottawattamie-Mills-Montgomery-Fremont- Page-Knox-Cedar-Thurston-Antelope-Pierce-Wayne-Boone-Madison- Stanton-Cuming-Burt-Platte-Colfax-Dodge-Washington-Butler- Saunders-Douglas-Sarpy-Seward-Lancaster-Cass-Otoe-Saline- Jefferson-Gage-Johnson-Nemaha-Pawnee-Richardson- 1201 PM CDT Wed Jun 28 2017 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST IOWA...WEST CENTRAL IOWA...EAST CENTRAL NEBRASKA...NORTHEAST NEBRASKA AND SOUTHEAST NEBRASKA. .DAY ONE...THIS AFTERNOON AND TONIGHT Severe thunderstorms with the primary hazards large hail and damaging winds are possible later this afternoon and evening generally south of Interstate 80. An isolated tornado is also possible. Strong instability will allow storms to quickly intensify and expand in areal coverage through the evening hours. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY Additional chances for severe thunderstorms will come Thursday afternoon and evening along a front meandering across the outlook area. Large hail and damaging winds will again be the main threat with storms. Thunderstorm chances continue Sunday through Monday night in association with upper level weather system moving across the region. .SPOTTER INFORMATION STATEMENT... Storm spotter activation may be needed this evening. Smith
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
951 AM CDT WED JUN 28 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0945 AM HEAVY RAIN 2 W ALVO 40.87N 96.42W
06/28/2017 M4.20 INCH CASS NE COCORAHS
STORM TOTAL
0945 AM HEAVY RAIN 8 ENE LINCOLN 40.86N 96.55W
06/28/2017 M3.60 INCH LANCASTER NE COCORAHS
STORM TOTAL
0945 AM HEAVY RAIN 1 ESE WEEPING WATER 40.86N 96.12W
06/28/2017 M2.88 INCH CASS NE COCORAHS
STORM TOTAL
0945 AM HEAVY RAIN 7 WNW RAYMOND 41.00N 96.91W
06/28/2017 M2.77 INCH LANCASTER NE COCORAHS
STORM TOTAL
0945 AM HEAVY RAIN 4 N LINCOLN 40.87N 96.69W
06/28/2017 M2.52 INCH LANCASTER NE COCORAHS
STORM TOTAL
0945 AM HEAVY RAIN W WAVERLY 40.91N 96.53W
06/28/2017 M2.82 INCH LANCASTER NE COCORAHS
STORM TOTAL
&&
KGPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1037 AM CDT WED JUN 28 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1037 AM HEAVY RAIN 7 NNE NEBRASKA CITY 40.77N 95.81W
06/28/2017 M3.38 INCH FREMONT IA PUBLIC
STORM TOTAL
&&
KGROSSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
346 PM CDT WED JUN 28 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0344 PM TORNADO 3 W SHENANDOAH 40.76N 95.43W
06/28/2017 FREMONT IA TRAINED SPOTTER
SPOTTER OBSERVED TORNADO DESCEND TO GROUND
&&
SFORTINThe Omaha radar (KOAX), 92 km away, was scanning. The volume nearest the first event began at 20:43 UTC.
6 hail, 2 tornado, 2 thunderstorm wind. Local standard time, as filed.
An EF2 tornado started 4 1/2 miles east-northeast of Sidney and moved east, paralleling Iowa Highway 2 for most of it's life cycle. The tornado flattened corn, uprooted and snapped trees, destroyed grain bins, flattened sheds and blew a roof off of a rural home.
A second weaker tornado from the same Supercell storm formed 4 miles east of Shenandoah and moved east southeast for a little over 2 miles. Most of the damage was limited to flattened corn and tree trunks being snapped by the tornado.
Large branches were blown down and metal panels were blown off of a shed at 202nd and Hickory.
A train storm spotter reported golf ball to tennis ball sized hail that cracked house siding and severely dented vehicles.
A report from a local radio station of baseball and tea cup size hail had fallen north of Shenandoah.
Several sheds had lost metal roof panels from damaging thunderstorm winds.
Ping-Pong ball size hail damaged siding on a home, and stripped leaves off of bean and corn crops about 6 1/2 miles south southeast of Farragut.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2017Every state in 2017This day in weather historyThe tornado archive for Iowa, 2017Warnings in Iowa, June 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: 710676, 710678, 710624, 710683, 710628, 710636, 710687, 710637, 710641, 710645.