Conditions averaged slightly wetter at 100 to 130 percent of normal during August, but the moisture was somewhat balanced by temperatures which were from 1 to 3 degrees above normal.
Every event with a place to put it; 6 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 FSD wrote it up.
Conditions averaged slightly wetter at 100 to 130 percent of normal during August, but the moisture was somewhat balanced by temperatures which were from 1 to 3 degrees above normal.
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 Sioux Falls, SD wrote its last area forecast discussion before the first event at Jul 31, 9:52 PM CST, 2 hours 8 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 1052 PM CDT Mon Jul 31 2023 .SHORT TERM...(This Evening through Tuesday) Issued at 249 PM CDT Mon Jul 31 2023 Surface high pressure to the east and northeast will help keep relatively stable air in place tonight into Tuesday. Better instability remains to the south and west during this time. This stable low level air coupled with a bit of an upper level ridge in place should keep conditions mainly dry tonight. A weak upper level wave is expected to move through on Tuesday and a few showers and isolated thunderstorms will be possible, especially near and south of I-90. For now instability is low enough that severe weather is highly unlikely. Lows tonight should be in the 60s with highs on Tuesday in the mid and upper 80s. .LONG TERM...(Tuesday Night through Monday) Issued at 249 PM CDT Mon Jul 31 2023 Tuesday night will see the continuation of shower and storm chances mainly south of I-90. Still just expecting a very low chance for severe. This chance should gradually fade through the night as the weak wave shifts east. As this wave moves out clouds should try to clear but with the weak easterly flow left behind, there could be a little stratus that develops behind the precipitation so clouds could be a little slower to exit on Wednesday, especially in northwest IA. Wednesday night into Thursday should see little chance for precipitation as upper level ridging builds. This will bring warmer readings to the region with lows in the 60s and highs mainly in the 90s. While it will be warm and a touch on the humid side, for now heat advisory criteria is not expected to be met. Thursday night into Friday night will see an upper level wave move from the northern Rockies onto the Plains. This will be the next better chance for showers and thunderstorms. At this time severe weather looks unlikely given the not very unstable model sounding output. Lows should be in the 60s with highs mostly mid to upper 80s. Saturday into Sunday will see the shower and thunderstorm threat slowly diminish as this wave moves east. Temperatures should be back below normal with highs from the upper 70s to mid 80s. Once again severe weather should be very isolated. For now Monday appears dry with temperatures below normal. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday Night) Issued at 1049 PM CDT Mon Jul 31 2023 VFR conditions are expected to dominate through the period. Still seeing potential for MVFR ceilings and/or visibility to expand into some areas south of US Hwy 18 late tonight or toward sunrise Tuesday. Confidence remains low, and it appears to be more favored east of KSUX, so will not include in the KSUX TAF at this time. Could see an area of -SHRA, perhaps with embedded TS, slide across areas south of I-90 Tuesday afternoon/evening. Will carry mention of -SHRA at KSUX, but potential for TS is too low to mention. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && SHORT TERM...08 LONG TERM...08 AVIATION...JH
Hazardous Weather Outlook National Weather Service Sioux Falls SD 504 PM CDT Mon Jul 31 2023 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-012215- Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Lincoln-Murray-Cottonwood-Nobles-Jackson- Pipestone-Rock-Dixon-Dakota-Beadle-Kingsbury-Brookings-Gregory- Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-McCook- Minnehaha-Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton- Union- 504 PM CDT Mon Jul 31 2023 This Hazardous Weather Outlook is for northwest Iowa, west central Iowa, southwest Minnesota, northeast Nebraska, central South Dakota, east central South Dakota, south central South Dakota and southeast South Dakota. .DAY ONE...Tonight. Hazardous weather is not expected at this time. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. There is a chance of showers and a few thunderstorms Tuesday into early Wednesday, mainly south of Interstate 90. Severe weather is not expected. Periodic chances for showers and thunderstorms return Thursday night into the weekend. Details on timing and location are uncertain, but at this time, the risk of severe weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The national radar mosaic for the moment the first event began.
6 drought. Local standard time, as filed.
Severe (D2) drought conditions persisted through August.
Severe (D2) drought conditions persisted through August.
Severe (D2) drought conditions persisted through August.
Severe (D2) drought conditions persisted through August.
Severe (D2) drought conditions persisted through August.
Extreme (D3) drought conditions persisted through August.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2023Every state in 2023This day in weather historyWarnings in Iowa, August 2023
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: 1129786, 1129787, 1129788, 1129789, 1129790, 1129791.