Active Weather
Iowa has been the busiest state in the country overnight, and it stays the one to watch today.
The National Weather Service office in Des Moines issued a flash flood warning for Dallas and Polk counties, which covers the Des Moines metropolitan area, expiring shortly after midnight Central time. The Sioux Falls office has a dense fog advisory until 9 AM Central time for Sioux, O'Brien, Plymouth, and Cherokee counties in northwest Iowa. Dense fog advisories mean visibility is expected to drop to a quarter mile or less, which changes the morning commute more than people expect. Slow down, use low beams rather than high beams because high beams reflect back off the fog, and leave more following distance than feels necessary.
The Storm Prediction Center's outlook covering last night into this morning placed a slight risk of severe thunderstorms across central and south central Iowa extending toward far eastern Nebraska, with a 15 percent probability of damaging wind gusts and no tornado or hail probability areas drawn. A marginal risk covered surrounding parts of Iowa, Nebraska, and Kansas.
Alongside it, the Weather Prediction Center placed a slight risk of excessive rainfall over most of Iowa, reaching into far eastern Nebraska, southeast Minnesota, southwest Wisconsin, and far northwest Illinois. Slight is the second of four levels. The forecaster's reasoning is worth repeating because it explains what happened in Des Moines: atmospheric moisture is running above 2 inches, short range models put the chance of an inch of rain in an hour at 65 to 85 percent, and the southwestern end of the front was expected to slow across eastern Nebraska and into Iowa, giving storms a chance to train, which means moving repeatedly over the same ground.
Heat advisories are in effect until 8 PM local time across south central Kansas including Sedgwick, Reno, Harvey, Butler, Greenwood, Woodson, Allen, Kingman, Harper, Sumner, Cowley, Elk, Wilson, Neosho, Chautauqua, Montgomery, and Labette counties, which covers Wichita. Missouri carries heat advisories across a broad area including the southeast counties of Dunklin, Pemiscot, and Mississippi. Nebraska has no heat products.
The National Weather Service instruction text on these products is the same everywhere: drink fluids, spend the hottest part of the day in an air conditioned room, stay out of the sun, wear light and loose clothing, and move strenuous work to early morning or evening. Check on relatives and neighbors, particularly anyone living alone without air conditioning. Never leave a child or a pet in a parked vehicle, even briefly. The Weather Service also passes along the Occupational Safety and Health Administration guidance to schedule frequent rest breaks in shade or air conditioning for outdoor work. Anyone overcome by heat should be moved somewhere cool and shaded, and the Weather Service treats heat stroke as an emergency call to 911.
If water is still standing on roads in central Iowa this morning, the National Weather Service's Turn Around, Don't Drown rule is the one to hold to. Do not drive into water across a road, and do not assume a familiar crossing is safe because you have driven it a hundred times.
Infrastructure
The most consequential item in this region is not a weather product. On September 1 the Federal Emergency Management Agency issued five major disaster declarations for severe storms, straight line winds, tornadoes, and flooding, and four of the five are in this region: DR-4943 and DR-4940 in Kansas, DR-4942 in Iowa, and DR-4939 in Missouri. A fifth, DR-4941 in South Dakota, is covered in the Mountain brief.
The important detail is which kind of assistance each one carries, because they are not the same. The Kansas, Iowa, and Missouri declarations carry Public Assistance only. Public Assistance funds debris removal and repair of roads, bridges, utilities, and public buildings. It is paid to state and local government, not to households. The South Dakota declaration is the only one of the five that also carries Individual Assistance, which is the category that pays households directly for temporary housing, home repair, and certain uninsured losses.
So if you were flooded in Iowa, Kansas, or Missouri in the incident period covered by these declarations, the declaration itself does not open a household application. That is worth knowing before you spend an evening on it. What can still help is your county emergency management office, your state's own disaster assistance programs, and the Small Business Administration disaster loan program, which sometimes operates where Individual Assistance does not. County designations and assistance types are listed at fema.gov.
No large wildfires are burning in the region in the National Interagency Fire Center's September 8 situation report.
No power outage events or water system notices are reported across the four states.
Public Health
The National Weather Service office in St. Louis has an air quality alert covering St. Charles, Franklin, St. Louis, St. Louis City, and Jefferson counties in Missouri, along with the Illinois side of the metro. Early September alerts here are typically ground level ozone, which builds on hot, sunny, still afternoons.
Move hard outdoor exercise to early morning today. If someone in the household uses a rescue inhaler, today is a good day to confirm where it is and that it has not expired.
No other air quality alerts are active in the region.
The Centers for Disease Control and Prevention Health Alert Network archive index could not be read again this morning, so we are not able to confirm either way whether a new national health advisory has posted. The most recent notice we could open directly was issued August 11 and is written for clinicians rather than households. If you want to check for yourself, the archive lives at emergency.cdc.gov/han.
Watch Item
The Weather Prediction Center's day 2 excessive rainfall outlook, valid Wednesday morning through Thursday morning, moves the slight risk southeast onto far southeast Kansas around Emporia, El Dorado, and Olathe, and central and southern Missouri around Boonville, Waynesville, Joplin, and Farmington. Short range models give a 55 to 75 percent chance of more than three inches somewhere in that area, and a 50 to 60 percent chance of an inch of rain in an hour sustained over three to five hours.
The center kept it at slight rather than raising it because the storms are expected to keep moving. That is the variable to watch. If storm motion slows, the same rain becomes a flash flood problem, and the Kansas City and Springfield areas are the ones to keep an eye on Wednesday evening.
The other thread is drought, which sits directly underneath this rain. The U.S. Drought Monitor map valid September 1 describes flash drought expanding through the southern Great Plains, the Mississippi Valley, and the Corn Belt, naming Kansas and Missouri specifically. Hardened ground sheds water rather than absorbing it, which is part of why the same counties can hold a drought designation and a flash flood warning in the same week. It is also why the September 1 disaster declarations and the drought map overlap almost exactly.
Seasonally, this is the last stretch of easy outdoor work before the weather turns here. Gutters, downspout extensions, and grading water away from a foundation are the three that pay off in the next flooding rain.
Explore Today
Why training storms turn an ordinary rain into a flash flood.
What federal assistance covers, what it does not, and where else to look.
How heat illness builds, who is most exposed, and what actually helps.