Despite improvement in late August and early September from rainfall, conditions dried out once again by late September with severe drought returning by the end of the month.
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
Despite improvement in late August and early September from rainfall, conditions dried out once again by late September with severe drought returning by the end of the month.
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 28, 5:24 AM CST, 1 hour 36 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 624 AM CDT Tue Sep 28 2021 ...Updated Aviation... .DISCUSSION.../Today through Monday/ Issued at 300 AM CDT Tue Sep 28 2021 Key Points - Couple more days of well above normal temperatures - Cooler, chances for rain latter half of week into the weekend All is quiet on the weather front over the forecast area tonight. 07z GOES water vapor imagery showed an upper ridge axis over the Great Plains states, riding over a nearly cutoff low over the Four Corners region. At the surface a diffuse stationary front was draped over central into southern Iowa. Temps near and south of the boundary have remained rather mild to this point generally in the 60s to low 70s. Cooler temps in the 50s to the north. The dome of anomalously warm 850mb temps beneath the Plains ridge begins to weaken a bit. However, a surface high over the Great Lakes pushes the frontal boundary south, thus allowing for a bit deeper boundary layer mixing compared to Monday thanks to marginally tighter surface pressure gradient and more unidirectional flow through the lowest 5000 feet. Thus expect highs to push well into the 80s to around 90 again today. Daily records are a little more difficult to reach today especially with the 99 degree marks at DSM and OTM set in 1953. An upper trough drops into the Pacific northwest on Wednesday which sets in motion a pattern change that will bring cooler temps and rain chances back to the area. The trough dislodges the southwest low which swings north and east as it is absorbed into the mean flow. Rain chances mostly hold off to the west Wednesday as appreciable moisture advection is focused more up the central Plains. This will keep above normal highs around for Wednesday, but likely knocked back a few degrees as mid/hi clouds increase. PoPs increase Wednesday night into Thursday as moisture transport veers eastward toward Iowa. The airmass becomes quite saturated as the western trough taps into some Pacific moisture as well, pushing PW values above the 90th percentile of NAEFS climatology. Models eject another weak impulse out of the southwest but provides only meager kinematic support. Instead models generate most precipitation via thermal contributions and isentropic lift which may result in a more broad precip shield. Still some timing and coverage differences within the latest model suite, but the highest probabilities and amounts will be focused near an inverted surface trough. The Euro/ECENS mean keep the trough hung up near or west of the Mo River while the GFS is further east toward I-35, with the NAM/GEFS mean somewhere in the middle. Latest NBM PoPs seem to have a reasonable handle on latest trends keeping the highest chances mostly west of I-35. A complex upper pattern develops late week into the weekend as models show multiple weak but well-defined waves drifting about and interacting with each other to varying degrees. Confidence is high that the early week heat will be a thing of the past as temperatures retreat to more seasonable norms. Rain chances on the other hand remain much more uncertain until models can get a better handle on pattern evolution through this time period. NBM has daily mention of PoPs, but this is likely overdone from a temporal standpoint and will have to suffice as more of a broadbrush approach until the more probable precip windows can be narrowed down. One such opportunity may occur over the weekend as a front is pushed south through the state. Thunder could mix in with the rainfall activity, however the threat of severe weather should stay low due to weak instability and shear profiles. && .AVIATION.../For the 12Z TAFS through 12Z Wednesday morning/ Issued at 623 AM CDT Tue Sep 28 2021 VFR conditions prevail through the current TAF period. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && DISCUSSION...Martin AVIATION...Martin
Hazardous Weather Outlook National Weather Service Des Moines IA 408 AM CDT Tue Sep 28 2021 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097-290915- 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- 408 AM CDT Tue Sep 28 2021 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Chances for periodic showers and thunderstorms return by Wednesday evening through Saturday afternoon. The chances of severe weather remain low at this time. .SPOTTER INFORMATION STATEMENT... Spotters will not be needed. REV
The national radar mosaic for the moment the first event began.
5 drought. Local standard time, as filed.
A warm month along with relatively dry condition throughout led to the development of severe drough in portions of Carroll county by late September.
A warm month along with relatively dry condition throughout led to the development of severe drough in portions of Greene county by late September.
A warm month along with relatively dry condition throughout led to the development of severe drough in portions of Polk county by late September.
A warm month along with relatively dry condition throughout led to the development of severe drough in portions of Jasper county by late September.
A warm month along with relatively dry condition throughout led to the development of severe drough in portions of Poweshiek county by late September.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2021Every state in 2021This day in weather historyWarnings in Iowa, September 2021
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: 981596, 981597, 981598, 981599, 981600.