An embedded shortwave within a larger upper level low swung across the area, bringing showers and thunderstorms to southern Iowa through much of the day. Repeated rounds of showers and thunderstorms across the area brought 3-4 inches of rain to the area with isolated pockets of over 6 inches of rain reported.
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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.
An embedded shortwave within a larger upper level low swung across the area, bringing showers and thunderstorms to southern Iowa through much of the day. Repeated rounds of showers and thunderstorms across the area brought 3-4 inches of rain to the area with isolated pockets of over 6 inches of rain reported.
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 May 1, 10:42 PM CST, 1 hour 18 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Des Moines IA 1142 PM CDT Wed May 1 2024 ...Updated for the 06z Aviation Discussion... .KEY MESSAGES... - Rain and storms moving in through this afternoon and overnight. Severe chances low and focused along the IA-MO border. Locally heavy rain possible in the south. - Rain continues Thursday with a focus in the southeast half of the state. Localized heavy rain impacts possible. - Dry Friday with additional precipitation expected Saturday and then again Monday. && .DISCUSSION... Issued at 253 PM CDT Wed May 1 2024 High pressure kept dry air in place through today with remnant midlevel cloud cover left aloft. The surface high will continue to depart this afternoon and make way for an approaching low from the southwest, bringing with it a strong push of theta-e advection from the wide open Gulf of Mexico. The main instability axis will be hugging along the IA-MO state border. CAMs have been differing on convection evolution this evening, but generally have some rain and storms moving in from the southwest through this afternoon. An MCS may form at the jet nose and move across southern Nebraska this evening and follow along the instability axis. A rogue severe wind gust or hail would be possible in the far south with this outcome, hence the marginal risk for severe weather on Day 1. As the convection moves into the area tonight, synoptic forcing from the approaching system takes over and spreads additional rainfall to much of the remainder of the state with much of this being in the southeast half. The LLJ will inch into the state and veer across it through Thursday, remaining parallel to the cold front and focusing the heaviest rainfall to the southeast half. Some Gulf transport will be obstructed from a trough in the south. Storm motion is also fast enough to limit heavy rain impacts from one specific storm. Some instability will work its way into the state Thursday with MUCAPE values nearing 1000 in the southeast. Profiles illustrate long, skinny CAPE profiles, meaning this instability will primarily contribute to more efficient rainfall production. The amount of instability is conditional to how the potential MCS modifies the near storm environment tonight. One would theorize the instability axis would be shoved further south from this outcome. A rogue severe storm cannot be ruled out, but with the better shear displaced behind the surface low, long-lived organization seems unlikely. Cannot rule out any mode of severe weather, but the risk is low. Any tornadoes that would form would be in the east where cloud bases will be low and the low level wind profile is elongated from the LLJ. Can expect rainfall amounts in the west totaling a half inch to an inch. The east and especially southeast will see the most rain in the area with 1-2 inches possible. Locally higher amounts will be possible in this region if storms can mature from better instability. Given the recent rounds of rainfall across southern Iowa, localized ponding and hydrologic impact is possible, especially since this time of year is in a favorable window for runoff. HEFS and NCRFC Ensemble output bring some river gages to action stage with higher river action possible if the higher amounts fall over the same basin (see hydro discussion for more). && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1142 PM CDT Wed May 1 2024 Scattered showers and thunderstorms have spread across central Iowa this evening with more widespread activity anticipated overnight and Thursday morning. Ceilings will drop to IFR as precipitation becomes more widespread, along with occasional visibility reductions within heavier rain. Thursday morning will see occasional gusts of 20-25 kts across all sites. As precipitation moves east of the area later Thursday ceilings return to VFR and winds shift to out of the northwest and diminish. && .HYDROLOGY... Issued at 253 PM CDT Wed May 1 2024 Recent heavy rainfall may lead to some flash flooding concerns over the next day or two along with longer term river flooding concerns. In terms of short-term response (flash flooding potential and urban flooding potential), the main concern would be later tonight through Thursday night. Antecedent conditions show the soil moisture is highest across the southern 2/3rds of the CWA with the highest values across the southwest quarter. Runoff would be increased where soil moisture is highest, however higher rates may lead to local issues regardless. As far as longer-term concern (rivers), hydrologic ensemble and QPF ensemble guidance is showing significant within-bank rises are likely on many rivers with several locations in the Des Moines, Raccoon, Skunk, Cedar and Iowa river basins reaching action stage. A few locations may reach flood stage especially if the rainfall comes in on the high side mainly in the Des Moines River basin above Des Moines. The peaks would occur later this week into this weekend. Conditions will have to continue to be monitored. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && DISCUSSION...Jimenez AVIATION...Hagenhoff HYDROLOGY...Zogg
Hazardous Weather Outlook National Weather Service Des Moines IA 325 PM CDT Wed May 1 2024 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097-022030- 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- 325 PM CDT Wed May 1 2024 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Tonight Chances for thunderstorms increase tonight especially across the southwest where some storms could be severe with damaging winds and hail. Locally heavy rainfall is also possible. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Showers and thunderstorms are likely Thursday with a low end chance for severe weather, especially in the southeast. All modes of severe weather are possible. Moderate to locally heavy rains are anticipated which may lead to standing water on fields and roads, as well as within bank rises on rivers and streams. Lower end chances late in the week and into the weekend. The severe weather threat looks low at this time, but will continue to be evaluated in the coming days. .SPOTTER INFORMATION STATEMENT... Spotters may be needed Thursday. Rainfall reports are appreciated.
The Des Moines radar (KDMX), 123 km away, was scanning. The volume nearest the first event began at 06:01 UTC.
4 heavy rain, 1 flash flood, 1 flood. Local standard time, as filed.
Monroe County EM reported a gauge with 6.13 inches of rain for the day as of 7:30 pm. An additional round of rain was moving towards the location at the time of report.
Personal weather station recorded 3.07 inches of rain.
Rainfall of 3.7 inches since 730 am. Several instances of minor creek flooding.
A 24 hour rain total of 4.8 inches. 3.7 inches fell between 730am and 630pm on May 2. Another 1.1 inches fell after 630p through 10p. Many creeks out of their banks.
Report of water over old pave US 34 near Albia to a depth of around 4.5 feet.
Emergency management reported road closures remaining for at least 10 roadways, some gravel and some paved. There were a total of 14 road closures for Monroe county for the day. Roads include Old Highway 34 east of Albia where up to 2 feet of standing water covers the roadway. Water is taking time to recede due to debris collecting at bridge culverts, especially in southeast portions of the county.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2024Every state in 2024This day in weather historyWarnings in Iowa, May 2024
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: 1182815, 1182811, 1182813, 1182824, 1182810, 1182820.