Temperatures averaged 3 to 5 degrees above normal during September, with precipitation varying from 25 to 50 percent of normal near the Minnesota border, to 50 to 75 percent of normal farther south.
Every event with a place to put it; 1 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.
Temperatures averaged 3 to 5 degrees above normal during September, with precipitation varying from 25 to 50 percent of normal near the Minnesota border, to 50 to 75 percent of normal farther south.
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 Sep 11, 9:41 PM CST, 2 hours 19 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 1041 PM CDT Mon Sep 11 2023 .SHORT TERM...(This Evening through Tuesday Night) Issued at 242 PM CDT Mon Sep 11 2023 Key Messages: 1. Sprinkles to light showers are are on the table for this afternoon. A rogue lightning strike and brief gusty winds are possible. 2. Mostly dry conditions continue through the middle of the week, with the next chance for rain arriving late Thursday. Specifics regarding rainfall are uncertain at this time. --------------------------------------------------------------------- Isolated sprinkles to light showers have developed early this afternoon while temperatures have warmed to the 70s. These sprinkles and light showers are being driven by nose of an upper level vorticity maximum advecting into the area. BUFKIT soundings show that there is steep enough mid-level lapse rates to generate a small amount of instability on the order of 100 J/kg of CAPE within a shallow moist layer. This moist layer is sitting around 600-700 mb and is above a dry layer beneath it. Any weak shower that develops will be capable of a few rumbles of thunder as well as brief gusty winds. Tonight will again be quiet and a bit cooler as lows fall to the mid to upper 40s. Although the low levels will be mostly dry, can't rule out a small possibility that river/valley fog developed in a few spots by tomorrow morning. With the forecast area remaining on the backside of an upper low, subsidence will prevail and keep sunny skies and mostly dry conditions locked over the Northern Plains. However, BUFKIT soundings continue to show a shallow moist layer around 700 mb along with minor instability on the order of 100 J/kg or less of CAPE mainly across northwest Iowa. As such, have introduced slight chance PoPs for this area. This could again lead to isolated sprinkles and showers that may produce a rogue lightning strike and perhaps brief gusty winds due to the dry layer below 700 mb. With 850 mb temperatures remaining in the low teens, highs again will warm to the upper 60s to 70s. Overnight low temperatures will fall to the mid 40s to low 50s from east to west. .LONG TERM...(Wednesday through Monday) Issued at 242 PM CDT Mon Sep 11 2023 Surface high pressure begins to slide eastward into the Midwest states on Wednesday. This will tighten the surface pressure gradient a bit while also setting up southerly return flow. A warm front will move across the area, increasing 850 mb temperatures to the mid teens and thus warm high temperatures into the 70s to low 80s. Forcing is negligible through so not expecting any rain chances. The previously mentioned tighter surface pressure gradient will bring a return to breezy winds with the strongest gusts up to around 25 mph across locations in central South Dakota. Shortwave ridging continues to pass through the Northern Plains, keeping conditions dry and quiet for the day on Thursday. Winds will further strengthen aloft on Thursday, with boundary layer winds increasing to 20+ knots. This will continue breezy conditions across the area for the daylight hours. High temperatures will also continue to further warm to the mid 70s to low 80s. The next chance for rain will come during the late evening and overnight hours as an upper level wave begins to move off the Rockies and into the Plains states. The Euro, GFS, and Canadian ensembles all show a 50-60% chance for exceeding a tenth of an inch of rain during this period of time. The wave will slowly push through the Central Plains, keeping rain chances going through Friday. Rain at this point looks to be driven by a potential deformation zone setting up across the area. Ensembles remain rather split on this rain potential as the Euro and Canadian ensembles keep similar probabilities for a exceeding a tenth of an inch of rain. The GFS shows dwindling probabilities, all the way down to a mere 10% chance for exceeding a tenth of an inch of rain. Given this uncertainty, have left model blended PoPs at this time. Broad upper level troughing continues through the weekend and into early next week. This will keep seasonable conditions with highs in the 70s to low 80s and lows in the 40s and 50s. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday Night) Issued at 1030 PM CDT Mon Sep 11 2023 Isolated very light rain showers or sprinkles will be possible overnight through mainly east central SD and southwestern MN, with little in the way of measurable precipitation. Otherwise, light and variable winds tonight. Winds will remain relatively light on Tuesday. There will be a small possiblity of isolated showers/sprinkles developing over northwest IA Tuesday afternoon with little impact. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && SHORT TERM...Meyers LONG TERM...Meyers AVIATION...JM
Hazardous Weather Outlook National Weather Service Sioux Falls SD 635 PM CDT Mon Sep 11 2023 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-122345- 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- 635 PM CDT Mon Sep 11 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. Isolated to scattered showers and thunderstorms will be possible through east central South Dakota and southwestern Minnesota during the evening. No severe storms are expected. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The national radar mosaic for the moment the first event began.
1 drought. Local standard time, as filed.
Moderate (D1) drought conditions worsened to severe (D2) in mid September.
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, September 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: 1138785.