A slow moving cold front in central Nebraska initiated storms during the evening of the 13th which became linear and progressed into Iowa during the overnight hours. Within an MLCAPE environment of 1000-2000 J/kg and lackluster effective shear, the only severe reports were a trio of damaging winds.
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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 DMX wrote it up.
A slow moving cold front in central Nebraska initiated storms during the evening of the 13th which became linear and progressed into Iowa during the overnight hours. Within an MLCAPE environment of 1000-2000 J/kg and lackluster effective shear, the only severe reports were a trio of damaging winds. In addition to the damaging winds, periods of brief heavy rainfall occurred in a number of locations.
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 Des Moines, IA wrote its last area forecast discussion before the first event at Jun 13, 11:14 PM CST, 12 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 1214 AM CDT Wed Jun 14 2017 .SHORT TERM.../Tonight through Wednesday/ Issued at 257 PM CDT Tue Jun 13 2017 The potential for strong to severe thunderstorms along with the continuation of above average temperatures are the highlights of the short term forecast. An upper level low centered over Montana will lift into the Dakotas through Wednesday. Ahead of the low, mid level dry air advection has continued across the Plains into the Midwest reinforcing the elevated mixed layer which will aid in suppressing convection this evening over Central Iowa. Further to the west, forecast model solutions depict thunderstorm initiation near a weak front over the Northern Plains aided by surface convergence and diffluent flow aloft. Convection is anticipated to continue to develop overnight into Wednesday supported by the low level jet. Forward propagating vectors favor thunderstorms tracking east overnight into Wednesday with the best chances for thunderstorms in Central Iowa after midnight. Some thunderstorms could be strong to severe with damaging winds the primary risk followed by large hail. Challenging temperature forecast on Wednesday dependent upon cloud cover and thunderstorm development. Highs once again though should be above average reaching the mid to upper 80s with lower 90s possible. .LONG TERM.../Wednesday night through Tuesday/ Issued at 257 PM CDT Tue Jun 13 2017 Precipitation chances will linger over the far east Wednesday evening then gradually end as drier air moves into the area. The large scale flow will become more zonal Thursday through Saturday as the upper low continues to depart to the north through Canada. The airmass should quickly recover during the day Thursday ahead of a surface boundary that will reach northwest Iowa by the morning. Proximity soundings ahead of the boundary show a destabilizing airmass by the afternoon with MLCAPEs exceeding 2000 J/kg as a surge of theta-e advection brings moisture back to the state. GFS instability likely too robust due to too high dew point forecast. Potential strong mixing on Thursday could lower dew points into the 50s which could keep weak capping in place. The lower dew points could also allow for stronger heating and highs well into the 90s. The potential for passing cirrus or mid-level clouds could limit instability though at this time does not appear to be a significant impact. Should have instability similar to the NAM solution develop. A short wave trough will arrive late in the day should provide enough forcing and mid-level cooling for a broken line of thunderstorms to develop late day and into the evening. Thick CAPE values through the mid-levels will support good updraft acceleration through this layer for large hail potential. In addition, a few damaging wind gusts could occur. The storm chances will continue into Thursday night. This solution is more inline with the American deterministic solutions which then build the elevated mixed layer back into Iowa for Friday. The ECMWF solution is dry Thursday night then precipitation on Friday. Two more chances for precipitation are expected Friday night then again Saturday night as a sfc boundary arrives along with short wave energy. A secondary boundary will arrive late Saturday night into Sunday and will usher in cooler conditions into Iowa. High temperatures by Sunday will be in the mid 70s to lower 80s and these conditions will continue into early next week. && .AVIATION.../For the 06Z TAFS through 06Z Wednesday night/ Issued at 1214 AM CDT Wed Jun 14 2017 The primary concern remains convective trends through the period. Scattered storms entered western IA this evening and produced outflow which will flip some TAF sites to west with some gusts for a period. After that wind confidence is low with chaotic flow. Cannot rule out lower conditions, but have kept TAFs VFR until conditions dictate otherwise. Similarly have only mentioned thunder based on near term terms with more generic VCSH later this morning and again east in the afternoon when additional storms could develop. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM...Angle LONG TERM...Donavon AVIATION...Small
Hazardous Weather Outlook National Weather Service Des Moines IA 319 PM CDT Tue Jun 13 2017 IAZ004>007-015>017-023>026-033>036-044>047-057-058-070-142030- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Pocahontas-Humboldt-Wright-Franklin-Sac-Calhoun-Webster-Hamilton- Crawford-Carroll-Greene-Boone-Audubon-Guthrie-Cass- 319 PM CDT Tue Jun 13 2017 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight Heat index values in the upper 90s to near 100 area expected through 7 pm. Thunderstorms are likely after 9 pm and into the overnight. A few severe storms may occur, with damaging winds the primary threat. Localized large hail may also occur. .DAYS TWO THROUGH SEVEN...Wednesday through Monday A few thunderstorms are possible on Wednesday. An isolated severe storm may occur. Periodic thunderstorms are possible from late Thursday into Saturday night with the most favored times during the overnight hours. A few severe storms may occur during this period. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through Wednesday though a few severe storms may occur overnight. IAZ027-028-037>039-048>050-059>062-071>075-081>086-092>097-142030- Butler-Bremer-Hardin-Grundy-Black Hawk-Story-Marshall-Tama-Dallas- Polk-Jasper-Poweshiek-Adair-Madison-Warren-Marion-Mahaska-Adams- Union-Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne- Appanoose-Davis- 319 PM CDT Tue Jun 13 2017 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight Heat index values in the upper 90s to near 100 area expected through 7 pm. Thunderstorms are possible mainly after midnight. A severe storm or two may occur with damaging winds the primary threat. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Scattered thunderstorms are possible on Wednesday. A few severe storms may occur late afternoon into the evening hours. Periodic thunderstorms are possible from late Thursday into Saturday night with the most favored times during the overnight hours. A few severe storms may occur during this period. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed late Wednesday.
Special Weather Statement National Weather Service Des Moines IA 1029 PM CDT Tue Jun 13 2017 IAZ004-005-015-023-024-033-034-044-045-140500- Emmet-Kossuth-Palo Alto-Pocahontas-Humboldt-Sac-Calhoun-Crawford- Carroll- Including the cities of Estherville, Algona, Emmetsburg, Pocahontas, Laurens, Rolfe, Fonda, Gilmore City, Humboldt, Sac City, Lake View, Odebolt, Wall Lake, Schaller, Early, Rockwell City, Manson, Lake City, Pomeroy, Denison, and Carroll 1029 PM CDT Tue Jun 13 2017 ....Storms with Gusty Wind Moving through Northwest Iowa... Thunderstorms will continue to move across west central and northwest Iowa late this evening. Some of the stronger storms may produce locally heavy rain and wind gusts to 50 mph through midnight along and west of a Carroll to Algona line, including the Estherville, Pocahontas, Sac City, Rockwell City and Denison areas. Small
The Des Moines radar (KDMX), 152 km away, was scanning. The volume nearest the first event began at 05:25 UTC.
4 thunderstorm wind. Local standard time, as filed.
Trained spotter reported the roof ripped off a Morton building. Some tree damage was reported as well.
Two 1 to 2 foot diameter trees were snapped near the base at a farm south of Forest City. Additional trees fell in the pasture to the north of their house.
Law enforcement reported power poles down near Highway S45 and McKimber street west of Knoxville.
Trained spotter reported one medium sized tree branch down in their backyard.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2017Every state in 2017This day in weather historyWarnings 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: 705373, 706784, 705374, 705375.