Severe to extreme drought conditions existed across the area in early September but widespread rainfall from September 8th to the 13th helped to improve conditions slightly. Little rainfall occurred during the remainder of the month with almost no change in drought conditions.
Every event with a place to put it; 19 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.
Severe to extreme drought conditions existed across the area in early September but widespread rainfall from September 8th to the 13th helped to improve conditions slightly. Little rainfall occurred during the remainder of the month with almost no change in drought conditions.
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 Aug 31, 10:42 PM CST, 1 hour 18 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 1142 PM CDT Mon Aug 31 2020 ...Updated 06z Aviation... .DISCUSSION.../Tonight through Monday/ Issued at 448 PM CDT Mon Aug 31 2020 The boundary that brought the early morning showers and storms was just exiting far southeast Iowa the afternoon. Much drier air was moving into the state as evidenced by the low 70 dewpoints near the boundary while northwest Iowa had dewpoints in the upper 30s to low 40s with an area of high pressure arriving. The area of high pressure will move east overnight with the primary influence over the northern 2/3rds of Iowa. A vigorous short wave dropping into Utah and Colorado tonight will lead to a slight shift to southwesterly flow for southern Iowa which will bring return flow aloft and will bring separate short wave across the area. The combination of the return flow, forcing and steepening lapse rates will lead to a few showers and thunderstorms across southern Iowa late tonight into Tuesday morning. Tuesday will be cool with highs in the low to mid 70s. Surface return flow will arrive Wednesday as the area of high pressure shifts to the east and the thermal ridge begins to build into the state ahead of a cold front that will arrive Thursday. Highs on Wednesday are expected to be well into the 80s. Precipitation chances will be nearly non-existent with the boundary passage Thursday will absolutely no moisture to work with which will result in large temperature and dew point spreads throughout the atmospheric column. A bigger question maybe if there will even be any attendant clouds as the boundary passes. Broad west to northwest flow will follow for Friday and Saturday with highs in the 70s and 80s along with dry conditions. Another vigorous short wave will drop through the upper flow and lead to a long wave trough forming over much of the Central and Northern Plains. Some scattered precipitation may occur with the boundary passage. A bigger impact may be the cooler conditions as 850 mb temperatures drop to 5C or lower by early next week. While it is still 7 days out, looks like it could be the coolest weather in several months. && .AVIATION.../For the 06Z TAFS through 06Z Tuesday night/ Issued at 1138 PM CDT Mon Aug 31 2020 The cold front has pushed southeastward out of Iowa late this evening. Surface high pressure has built in behind it. Gusty winds post-frontal passage have now subsided, which will lead to a calm overnight at the Iowa terminals. Most terminals will see clear conditions for most of Tuesday. The one exception is OTM, which will see influence from a short-wave passing south. While the bulk of activity will be in Missouri, expecting rain showers and isolated thunderstorms, as well as denser cloud cover to clip southern and southeast portions of Iowa. Thus, will place VCTS at OTM for the early afternoon hours with MVFR CIGs. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && DISCUSSION...Cogil/Donavon AVIATION...Krull
Hazardous Weather Outlook National Weather Service Des Moines IA 244 PM CDT Mon Aug 31 2020 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097-011945- 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- 244 PM CDT Mon Aug 31 2020 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This Afternoon and Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Showers and thunderstorms will be possible across southern Iowa Tuesday. The severe threat will be low. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed. Hagenhoff
The national radar mosaic for the moment the first event began.
19 drought. Local standard time, as filed.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Pocahontas county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Sac county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Calhoun county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Webster county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Hamilton county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Crawford county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Carroll county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Greene county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Boone county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Audubon county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Guthrie county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Dallas county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across northwest Polk county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Cass county.
Severe to Extreme drought conditions were helped by widespread soaking rains from September 8th to the 13th. Extreme conditions improved to severe for the remainder of the month from the 15th onward across Adair county.
Despite some generous rainfall from September 8th to the 13th, severe drought continued for portions of Palo Alto county through the month.
Despite some generous rainfall from September 8th to the 13th, severe drought continued for portions of Story county through the month.
Despite some generous rainfall from September 8th to the 13th, severe drought continued for portions of Madison county through the month.
Despite some generous rainfall from September 8th to the 13th, severe drought continued for portions of Adams county through the month.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2020Every state in 2020This day in weather historyWarnings in Iowa, September 2020
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: 915671, 915672, 915673, 915674, 915675, 915676, 915677, 915678, 915679, 915680, 915681, 915683, 915684, 915685, 915686, 915688, 915690, 915691, 915693.