Increasingly humid conditions, a weak low pressure system, and an impinging northern weak cold front combined to create an environment ripe for strong to severe storms across northern and central Iowa, with much of the severe activity through central Iowa. The resulting environment from the aforementioned ingredients included SBCAPE values in the 2000-3000+ J/kg range, marginal effective bulk…
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The episode as NWS DMX wrote it up.
Increasingly humid conditions, a weak low pressure system, and an impinging northern weak cold front combined to create an environment ripe for strong to severe storms across northern and central Iowa, with much of the severe activity through central Iowa.
The resulting environment from the aforementioned ingredients included SBCAPE values in the 2000-3000+ J/kg range, marginal effective bulk shear around 30 kts, 400-600 J/kg CAPE in the hail growth region, and at least a few hours with steep low level lapse rates around or greater than 8 deg C/km. All in all while the environment did not lend much support to long lived strong to severe storms, it was more than enough for brief periods of severe storms as many pulsed up and down prior to congealing into multi-cellular clusters and eventually an mesoscale convective system by the evening. Most reports revolved around severe and damaging winds, with a few instances of hail, heavy rainfall, and a land-spout reported north of Whitten in Hardin county.
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 15, 11:32 AM CST, 28 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 1232 PM CDT Sat Jun 15 2019 .DISCUSSION.../Today through Friday/ Issued at 333 AM CDT Sat Jun 15 2019 The primary concern this morning will be convective trends with likely events later today into this evening, around Tuesday/Wednesday, and then a few others later into the extended forecast. The current situation has a short wave/MCV pushing through KS with associated convection attempting to blossom across northern MO and far southern IA in an axis of 0-2km moisture convergence. The typical nocturnal support is not impressive however with rather weak warm/theta-e advection this far north, and the northern MO convection will likely struggle to get too far north based on Corfidi vectors pulling cells south and the better H85 flow and moisture convergence staying to our south. Thus will keep some low PoPs south this morning. Whatever does materialize should likely stay below severe limits. Although MUCAPEs are 1-2K j/kg, effective shear is minimal. Attention will then turn upstream to our NW with synoptic scale lift increasing ahead of the approaching MT/ND short wave/PV anomaly. Although much of it will stay to our north, this feature will increase our QG forcing to some degree and likely increase convection NW into peak heating. Both NAM and GFS upstream dewpoints are overdone versus 07z obs, especially the NAM, so will stay closer to lower GFS expectations and 2-3K j/kg MLCAPEs by afternoon. Expect convection to develop along the weak surface front/trough reflection by early afternoon at the latest and progress slowly south and east into the evening before exiting toward midnight. Deep shear is initially weak, but does increase a bit by 00z-03z so the potential for organization and supercells does increase a into the day. Even so the shear is never too much so the severe potential will likely stay toward a low end Slight Risk per the current Day 1 outlook. The HREF calibrated severe guidance reflects this thinking as well. Nevertheless there will be some large hail and damaging wind possible and even a minimal stretching/thermodynamically dominate tornado potential, especially if the higher end of the instability spread is realized even though the low level shear is weak. The heavy rain parameter space is not overly impressive and near seasonal normals, but there could still be some locally heavy rains, mainly due to storm motions no better than 20kts as shown by the mean wind and Bunkers supercell motion. Although it should be quite warm and humid today, the weekend warmth and humidity should drop off again somewhat as we start a few days of dry weather into early next week. Our next precip window will be Tuesday into Wednesday, but confidence here and beyond is not great due to subtle features. However both the ECMWF and GFS show large scale forcing into IA during peak heating Tue, and another following wave Wed. The weak surface flow will not really allow for much preceding return flow however so both instability and shear will be low keeping the severe weather potential minimal. The flow will remain somewhat weak in the extended although the pattern will change somewhat as brief ridging transitions to some degree of SW flow aloft. Predictability is low because of this persistent weak flow and ill-defined short waves and associated surface features, but the overall pattern supports a prolonged period of low end PoPs. The potential for strong to severe convection may increase somewhat again toward the end of the period however as a bit stronger SW flow will increase our deep shear and allow for a return to climatological instability. && .AVIATION.../For the 18Z TAFS through 18Z Sunday afternoon/ Issued at 1231 PM CDT Sat Jun 15 2019 Weak boundary situated over central/eastern sections aiding in development of iso thunder at 17z and expect some convection to pop and recycle through mid afternoon. More organized convection expected aft 22z over central/northwest areas as larger portion of the region realizes CAPE release. Have mainly VCTS/VCSH for now but will monitor for potential better timing of categorical chances. Winds rather light except near convection. MVFR/IFR cigs move into northeast sections at KMCW/KALO/KFOD from 12-18z Sunday as southern sites KDSM/KOTM generally VFR through period. /rev && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && DISCUSSION...Small AVIATION...REV
Hazardous Weather Outlook National Weather Service Des Moines IA 436 AM CDT Sat Jun 15 2019 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097-160945- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun- Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford-Carroll-Greene- Boone-Story-Marshall-Tama-Audubon-Guthrie-Dallas-Polk-Jasper- Poweshiek-Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-Union- Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne- Appanoose-Davis- 436 AM CDT Sat Jun 15 2019 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight Non-severe thunderstorms are possible through this morning across southern Iowa. Strong to severe thunderstorms are possible this afternoon and evening. The main threats are lightning, large hail, and damaging winds. .DAYS TWO THROUGH SEVEN...Sunday through Friday Thunderstorms are possible Tuesday through Thursday. At this time, the predictability of severe weather is too low. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon and evening. Kotenberg
The Des Moines radar (KDMX), 101 km away, was scanning. The volume nearest the first event began at 18:00 UTC.
19 thunderstorm wind, 2 flash flood, 2 hail, 1 heavy rain, 1 tornado. Local standard time, as filed.
Coop observer reported heavy rainfall of 2.28 inches. Beginning and ending times estimated from radar.
Emergency manager reported trees down in Eldora.
Landspout captured on video destroyed a very old barn before dissipating. The tornado was moving very slowly to the east southeast.
Public reported a tree snapped in Fort Dodge near Great Western Bank.
Emergency manager reported some roads washed out near the Grundy-Hardin County line, as well as some roads washed out near Owasa in Hardin County.
Local fire department reported large limbs down around Perry. Times estimated from radar.
Law enforcement reported trees down in Gilbert.
Law enforcement reported a tree down that was blocking the road at the intersection of 270th and Y Ave.
Public relayed picture of an 18 inch diameter tree snapped.
Ames Municipal Airport ASOS recorded a 72 mph wind gust.
WHO TV relayed reports of a large tree downed near Slater.
Law enforcement relayed reports of a tree down in Maxwell.
Marshalltown Municipal Airport ASOS recorded a 68 mph wind gust.
Public relayed images of tree and power pole damage. Time estimated from radar.
WOI TV relayed viewer photo of a large tree snapped near SW 18th St and Army Post Rd in Des Moines.
Trained spotter estimated 60 to 70 mph wind gusts near Blank Park Zoo.
Des Moines International Airport ASOS recorded a 70 mph wind gust.
Public relayed images of tree branches and power lines down. Time estimated from radar.
Public reported a couple large tree limbs down with one estimated around a foot in diameter falling and damaging a chain link fence on Wade St. Another 5 inch diameter tree branch was down on Mason Ave from the storm. Time estimated from radar.
Law enforcement reported trees down in Gladbrook. Time estimated from radar.
Law enforcement reported trees down in Montour. Time estimated from radar.
Public reported nickel sized hail.
Emergency manager reported 4 plus inches of rain and flash flooding including basements filling due to an already high water table.
Public reported quarter sized hail via the mPING app.
Public relayed images of tree damage in far western Ottumwa. Time estimated from radar.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2019Every state in 2019This day in weather historyThe tornado archive for Iowa, 2019Warnings in Iowa, June 2019
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: 825088, 825054, 838494, 825055, 825059, 825060, 825062, 825063, 825065, 825066, 825067, 825068, 825070, 825071, 825073, 825074, 825075, 825076, 825078, 825079, 825080, 825082, 825083, 825084, 825086.