A relatively cool, but juicy atmosphere existed across the area with southerly surface winds dominating and southwesterly mid and upper level flow. During the early morning hours of the 9th, scattered thunderstorms aided by the low level jet remained predominantly sub-severe with small hail.
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 DMX wrote it up.
A relatively cool, but juicy atmosphere existed across the area with southerly surface winds dominating and southwesterly mid and upper level flow. During the early morning hours of the 9th, scattered thunderstorms aided by the low level jet remained predominantly sub-severe with small hail. Through the morning and early afternoon hours, a surface warm front entered and moved across the state from southwest to northeast, all the while increasing MUCAPE values across the southeast half to two thirds of the state into the 2000-4000+ J/kg range. Additionally, moderate to steep low level lapse rates boosted DCAPE values into the 1000-1300 J/kg range, increasing the potential for strong downdrafts and resulting surface winds. Effective bulk shear was marginal through most of the event, yielding around 30 to 40kts.
Resulting storms generally rolled through the state in waves from southwest to northeast, with at least periods of organization. The primary cluster of storms rolled through during the late afternoon, producing a fairly consistent trail severe thunderstorm winds and thunderstorm wind damage from southwest of Des Moines all the way through the Waterloo area. A second round of at least brief sever storms moved through overnight just southeast of the Des Moines metro, but was short lived unlike the cluster earlier in the day.
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 Sep 9, 2:14 PM CST, 46 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 314 PM CDT Mon Sep 9 2019 .DISCUSSION.../Tonight through Monday/ Issued at 314 PM CDT Mon Sep 9 2019 Surface boundary has made slow progress north into central Iowa this afternoon with isolated to scattered convection. Instability has increased rapidly in the warm sector with 100MB Mixed-Layer CAPE of around 2000 J/KG in southwest Iowa. There is a very tight gradient of CAPE along the boundary and this will be the focus area late this afternoon into the evening of any potential severe storms. Shear along this boundary is quite robust with bulk parameters of 30-40kts in the first kilometer. While the low level shear is quite good along with the 0-3km CAPE of 100-150 J/KG, mid level lapse rates are somewhat weak. This would suggest an overall limit on hail size without stronger mid level accelerations. However, the tornado threat will still remain given the low LCL, decent low level CAPE and the strong near low level shear. The main concern will be as storms approach/intersect the boundary where the increased helicity would support quick spin-ups. All the activity will lift northeast this evening and will pass into MN later in the evening. However, additional forcing is forecast along the low level moisture transport axis overnight with additional convection. This will produce an axis of storms from southwest to northeast across the forecast area during the night which will shift slightly south as a the front heads back south toward daybreak. Locally heavy rainfall is expected with the storms as the train over the same areas, although most areas can handle some decent rainfall. The convection will gradually subside Tuesday morning with a break from storms for much of the day as forcing will remain negligible. Additional convection is expected in Tuesday night/early Wednesday, primarily across the northern half of the state where near the location of a warm front. Strong moisture transport into the boundary overnight will support convection which is expected to be moving east into Iowa from Nebraska and South Dakota. The main threat will be from heavy rainfall but some gusty winds are also expected. With the boundary lifting northward into later Wednesday/early Thursday, the threat of storms will be relegated to northern Iowa with warm and humid conditions in central and southern Iowa. The main western trof approaches on Thursday with a stronger synoptic boundary crossing the state during the day. Convection, possibly severe, is expected to cross central into eastern Iowa by midday into the evening before cooler and drier air arrives in the wake of the front. Thereafter, much of the weather will be quiet Thursday night into early next week except for some threat of storm Saturday night into early Sunday with a surge of theta-e advection. && .AVIATION.../For the 18Z TAFS through 18Z Tuesday afternoon/ Issued at 1242 PM CDT Mon Sep 9 2019 Warm front is lifting through the state this afternoon with widespread MVFR to IFR status and fog across northeast Iowa. Conditions will improve across the northeast as the front continues to move north into the evening. Convection is forecast to fire by mid to late afternoon in western Iowa and spread north and east into the evening. While mainly VFR conditions are expected at this time, MVFR to isold IFR ceilings and visibilities are forecast in and around thunderstorms. Elevated convection will persist near low level moisture transport axis overnight with occasional MVFR conditions where the showers are occurring. Winds will be from the south for much of the period and gusty. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && DISCUSSION...Cogil AVIATION...Cogil
Hazardous Weather Outlook National Weather Service Des Moines IA 1251 PM CDT Mon Sep 9 2019 IAZ070>075-081>086-092>097-101800- Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-Union-Clarke-Lucas- Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne-Appanoose-Davis- 1251 PM CDT Mon Sep 9 2019 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight Thunderstorms are possible this afternoon and evening. At this time, the threat for severe weather is marginal. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Thunderstorms are possible Wednesday and Thursday afternoon and evenings. A few of these storms could be strong to severe...especially Thursday afternoon and evening. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time, but cannot be ruled out later in the week. IAZ004>007-015>017-023>028-033>039-044>050-057>062-101800- 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- 1251 PM CDT Mon Sep 9 2019 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight Strong to severe thunderstorms are possible this afternoon through this evening. Tornadoes and damaging winds are the primary threats, with large hail a secondary threat. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Thunderstorms are possible Tuesday... Wednesday... and Thursday afternoon and evenings. A few of these storms could be strong to severe...especially on Thursday afternoon and evening. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon and evening... and also again later this week. Kotenberg
The Des Moines radar (KDMX), 61 km away, was scanning. The volume nearest the first event began at 21:00 UTC.
25 thunderstorm wind, 2 tornado, 1 lightning. Local standard time, as filed.
Emergency manager relayed law enforcement reports of 4 to 6 inch diameter tree limbs down in Menlo. Time estimated from radar.
Small tornado moved through open cropland. No damage indicators were impacted, therefore the rating was EFU. Path was found using high resolution satellite imagery.
Tornado remained in open cropland east and northeast of Minburn. No damage indicators were impacted, therefore the EFU rating. The tornado path was discovered using high resolution satellite imagery.
Minburn Fire Department reported 12 inch diameter tree snapped. The report was relayed by Dallas County Emergency Management and the time is estimated from radar.
Trained spotter reported telephone pole leaned over as well as a no passing sign leaned over. This is a delayed report and time estimated from radar.
Law enforcement reported a large tree down at 10th Street and Division.
Ames Police reported wall of a building pushed in about 6 feet, damage to the walls and doors, contents inside blown around, as well as trees down in the area. Time estimated from radar.
Emergency manager reported a 10 to 12 inch tree branch down on a power line. Also tree debris across a 3 to 4 block swath on the north side of town.
The Emergency manager reported a swath of corn blown down between Collins and Maxwell.
Storm chaser reported thunderstorm wind gusts of 61 mph via personal equipment. Report came via social media.
Emergency manager reported a broken power pole at the intersection of White Pole Road and Adair Street.
Trained spotter estimated 70 mph winds. Also reported 10 inch diameter tree limb down from an older tree, and multiple 3 to 4 inch tree limbs down on newer trees.
Law enforcement reported several large tree limbs down throughout Parkersburg, as well as a couple trees reported to have fallen on homes. Time estimated from radar.
Trained spotter reported tree damage around Conrad, as well as a couple power lines down. Time estimated from radar.
Law enforcement reported a large tree limb down on a home in Clarksville. Time estimated from radar.
Law enforcement reported several large tree limbs, including a few large ones, down throughout the town of Shell Rock. Some were blocking the street. Time estimated from radar.
Law enforcement reported that lightning struck a utility pole. This is a delayed report and time estimated from radar.
A trained spotter reported 3 inch tree limbs down on the campus of UNI.
Waterloo Regional Airport ASOS recorded 62 mph wind gusts.
Trained spotter reported multiple trees down south of Hubbard. One of the trees was 24 inches in diameter. Spotter estimated wind gusts over 60 mph.
Public reported wind damage via the mPING app.
Public reported 60 mph wind gusts.
Marshalltown Municipal Airport ASOS recorded a 59 mph wind gust.
Public reported estimated 60 mph wind gusts.
Trained spotter reported damage to mobile home skirting as well as 2.5 inch diameter tree limbs down. Time estimated from radar.
Trained spotter reported estimated 60 mph wind gusts just northwest of La Porte City on Highway 218 near Eagle Road.
Trained spotter reported trees down in the neighborhood, including winds over 60 mph.
Des Moines Public Safety reported a tree fell on a power line, causing power flashes in south Des Moines.
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, September 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: 855646, 867246, 867247, 855648, 855649, 855651, 855652, 856251, 856252, 855653, 855654, 855655, 855656, 855657, 855658, 855659, 855660, 856250, 855661, 855662, 855664, 855663, 855665, 855666, 855667, 855668, 855669, 855670.