Generally speaking, there was not much to write home about with regards to the synoptic setup for severe or highly impactful weather. Even so, an environment with nominal MUCAPE (often under 1000 J/kg), high shear (0-1km shear in excess of 30 kts, 0-1km helicity in excess of 200 m2/s2), and consistent low level moisture transport was able to produce weak, brief tornadoes and sustained periods of…
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.
Generally speaking, there was not much to write home about with regards to the synoptic setup for severe or highly impactful weather. Even so, an environment with nominal MUCAPE (often under 1000 J/kg), high shear (0-1km shear in excess of 30 kts, 0-1km helicity in excess of 200 m2/s2), and consistent low level moisture transport was able to produce weak, brief tornadoes and sustained periods of moderate to heavy rainfall.
Specifically on the tornadoes, two brief weak tornadoes occurred in the relatively low CAPE, high shear environment in central Iowa. Little impact was observed from the tornadoes as they stayed in rural areas and away from structures and towns.
On the rainfall front, multiple rounds of showers and storms produced numerous reports of 2 to 3 inches of rainfall throughout southern Iowa, even trickling north into central Iowa in a few instances.
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 21, 5:12 AM CST, 48 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 612 AM CDT Sat Sep 21 2019 .DISCUSSION.../Today through Friday/ Issued at 431 AM CDT Sat Sep 21 2019 ...Updated for 12z Aviation Discussion... */ Highlights... -Scattered storms through most of today, followed by slight risk of severe weather this evening for SW Iowa -Widespread showers and storms expected tonight through Sunday morning... potentially bringing heavy rainfall to southern/SE Iowa. -Above-normal temperatures and precipitation expected for next week. */ Summary... Scattered showers and storms ongoing across Iowa should yield no hazards aside from lightning. For Saturday late afternoon and through the evening, a slight risk of severe weather exists... primarily in southwestern Iowa to west-central Iowa. Overall, the ingredients continue to look slightly weaker for this event than the forecast models were showing yesterday. Damaging winds and large hail are the primary threats with any storms that may become severe. A brief spin-up tornado or two cannot be completely ruled out either. The general track of the storms along and north of I-80 should be west to east. In SW Iowa, the storms may have a slight more SW to NE component of motion to them. For Saturday night into Sunday morning, the threat shifts to heavy rainfall... particularly across southern to southeastern Iowa. A widespread 1 to 2 inches of rainfall is forecast from around Creston to Pella and south/southeast. Nearing Ottumwa and southeastern Iowa, total forecast rainfall amounts may near 3 inches. This will likely come in two larger surges... the first surge from around 7 pm through midnight tonight... the second surge tomorrow morning near sunrise through mid-morning. Looking ahead to next week, Iowa seems to be setup for westerly to southwesterly flow. This suggests above normal temperatures will likely continue, with several rounds of precip possible. As such, have begun to boost daytime temperatures versus model guidance. At this time, Tuesday into Wednesday, and both Friday and Saturday are the most favored time-frames for precipitation. Further, there is a non-zero severe weather threat for Friday and Saturday. */ Technical Discussion... Synoptic-scale setup... 08z Sat water vapor imagery shows two upper lows more or less going through a Fujiwara effect over the Intermountain West. By 00z Mon, the resultant trough of this interaction should be entering into Minnesota. Meanwhile, incredibly broad anti-cyclonic flow from 850- 300mb is over the SE CONUS. This large-scale setup is producing a strong fetch of SW winds that goes into the Baja of California. Currently in the Baja of California, more or less stalled out, is Hurricane Lorena. GOES-R water vapor channels show moisture from this hurricane already being advected into west Texas towards the Permian Basin. This morning... With the sfc reflection low beginning to take form over North Dakota via the aforementioned upper low interaction, the warm advection wing- highlighted by several NW-SE ribbons of theta-e advection coupled with distinct 850 moisture flux convergence are slated to be advected through Iowa during the morning hours... supporting continued scattered showers and thunderstorms across most of the state. This evening... As has been well-advertised a N-S oriented attendant boundary to the parent low over North Dakota is slated to propagate across Iowa from west to east during peak heating. Over the past several days, the timing of this boundary has been delayed to being over west-central Iowa during peak heating. The major inhibitor of significant convection the past few days during peak heating has been an abundant shortfall of shear/0-6km wind profile support. With the strong SW flow arriving, a 30 to 40 kt LLJ ends the lack of shear. Strong winds and large hail are in play as low-level lapse rates near the boundary are rather impressive for this time of year. SW Iowa, from Creston through around St. Joseph, MO, is a particular area of intersect as pocket of strong forcing and vertical ascent- supporting processes arrive in the 21z Sun to 03z Sun timeframe. After sundown, these storms will likely continue to move into NE Iowa, but the severe wx threat should wane. Tonight Through Sunday Morning... Heavy rainfall potential continues as advertised. Will keep mesoscale details brief, other than to say that heavy and efficient rainfall processes are very well supported. PWATs over 2 inches are highly abnormal in Iowa for this time of year. Models generally converging on a solution that brings northern edge of slug of heaviest precip into the southern to southeastern two or so tiers of counties in the DMX CWA. Thus, have made no changes to location of Flash Flood Watch. Mitigating factor to Flash flooding is the fact that this part of Iowa has received little to no rainfall the past 7 to 10 days. In the past 11 days, the Lamoni ASOS has recorded 0.01 inches of precipitation... obviously suggesting very dry ground. For flash flooding to stick, it would most likely be caused by multiple rounds locally intense rainfall over a short period of time... versus a slow, steady, drawn-out rainfall event. The heaviest rainfall should have fallen by noon Sunday. Rest of Next Week... As mentioned above, westerly to SW flow favored, with above- normal rainfall and precipitation chances. Rainfall chances Tuesday into Wednesday may need to be amplified as signal for rain has been in the forecast for the past 5 days... implying solid run-to-run consistency. PWATs for this timeframe appear to be in the 1.25 to 1.5 inch max range... implying much light precip potential than this weekend. Towards next weekend, long-range models are hinting that the Gulf of Mexico may be reopened again... suggesting the potential for strong moisture advection and potentially more heavy rainfall and strong/severe storms. Will keep an eye on this. && .AVIATION.../For the 12Z TAFS through 12Z Sunday morning/ Issued at 610 AM CDT Sat Sep 21 2019 Highly active fcst period. Have left precip mention out of TAFs this morning through the afternoon, except for KOTM. Non-KOTM sites may be briefly impacted by showers and a rumble of thunder, but confidence in timing and location too low to mention. Confidence increases in showers and thunderstorms moving from west to east across Iowa this evening through Sunday morning. KOTM and KDSM especially to be impacted. VSBYs will need to be monitored, as periods of heavy rainfall may drop flight categories to IFR during periods of heavier rain. && .DMX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from this evening through Sunday evening for IAZ074-075-083>086-092>097. && DISCUSSION...Kotenberg AVIATION...Kotenberg
Hazardous Weather Outlook National Weather Service Des Moines IA 444 AM CDT Sat Sep 21 2019 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>073-081- 082-220945- 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-Adams-Union- 444 AM CDT Sat Sep 21 2019 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight Scattered thunderstorms are possible throughout much of today and into Sunday morning. A few storms may be strong to severe late this afternoon and evening... especially west and southwest. Damaging winds and large hail are the primary threats with any storms that may become strong to severe. A brief spin-up tornado or two...though not likely...cannot be ruled out at this time. .DAYS TWO THROUGH SEVEN...Sunday through Friday Non-severe thunderstorms are possible Sunday morning through Sunday afternoon...especially east and southeast. Periodic thunderstorms are forecast Tuesday through Friday. A few storms may be at least strong on Friday. The potential for the severe weather will be refined in the coming days. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed late this afternoon and evening...especially west and southwest. IAZ074-075-083>086-092>097-220945- Marion-Mahaska-Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold- Decatur-Wayne-Appanoose-Davis- 444 AM CDT Sat Sep 21 2019 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight A Flash Flood Watch is in effect for the area tonight through Sunday. Please refer to the National Weather Service website at weather.gov/desmoines for further details. Scattered thunderstorms are possible throughout much of today and into Sunday morning. A few storms may be strong to severe late this afternoon and evening... especially west and southwest. Damaging winds and large hail are the primary threats with any storms that may become strong to severe. A brief spin-up tornado or two...though not likely...cannot be ruled out at this time. .DAYS TWO THROUGH SEVEN...Sunday through Friday A Flash Flood Watch is in effect for the area through Sunday. Please refer to the National Weather Service website at weather.gov/desmoines for further details. Non-severe thunderstorms are possible Sunday morning through Sunday afternoon. Periodic thunderstorms are forecast Tuesday through Friday. A few storms may be at least strong on Friday. The potential for the severe weather will be refined in the coming days. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed late this afternoon and evening...especially west and southwest. Rainfall and or flooding reports are always appreciated. Kotenberg
The Des Moines radar (KDMX), 130 km away, was scanning. The volume nearest the first event began at 11:59 UTC.
27 heavy rain, 2 tornado, 1 hail. Local standard time, as filed.
Coop observer recorded heavy rainfall of 3.60 inches over the last 24 hours.
Centerville Municipal Airport AWOS recorded heavy rainfall of 3.01 inches over the last 24 hours.
Coop observer recorded heavy rainfall of 2.16 inches over the last 24 hours.
Coop observer recorded heavy rainfall of 2.07 inches over the last 24 hours.
Coop observer recorded heavy rainfall of 2.10 inches over the last 24 hours.
Coop observer recorded heavy rainfall of 2.31 inches over the last 24 hours.
Coop observer recorded heavy rainfall of 2.57 inches over the last 24 hours.
Coop observer recorded heavy rainfall of 2.09 inches over the last 24 hours.
Coop observer recorded heavy rainfall of 2.09 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 2.80 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 2.13 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 2.19 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 2.15 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 2.12 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 2.57 inches over the last 24 hours.
Coop observer recorded heavy rainfall of 2.60 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 2.70 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 2.35 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 2.19 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 2.00 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 3.75 inches over the last 24 hours.
CoCoRaHS observer recorded heavy rainfall of 2.09 inches over the last 24 hours.
Fort Dodge Regional Airport AWOS recorded heavy rainfall of 2.56 inches over the last 24 hours.
Mesonet station recorded heavy rainfall of 2.08 inches over the last 24 hours.
Trained spotter reported heavy rainfall of 2.25 inches. Time duration unknown. Set at 24 hours for the report.
Public reported heavy rainfall of 2.50 inches. Time duration unknown. Set at 24 hours for this report.
Public reported heavy rainfall of 2.10 inches as a 24 hour report ending at 6pm this evening.
Time and exact location estimated from radar.
The tornado was suggested by a TDS observed on radar and subsequently confirmed via high resolution satellite data. The tornado remained in either wooded areas or open cropland with no damage noted, therefore the EF-U rating.
Tornado was suggested by a TDS on radar and subsequently confirmed via high resolution satellite imagery. A short path through rural cropland, hence the EF-U rating.
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: 855760, 855761, 855762, 855763, 855764, 855765, 855766, 855767, 855768, 855769, 855770, 855771, 855772, 855773, 855774, 855775, 855776, 855777, 855778, 855779, 855780, 855781, 855782, 855783, 855784, 855785, 855786, 855759, 850406, 850407.