Very hot and dry conditions in the second half of August led to rapid expansion of drought conditions in portions of Iowa.
Every event with a place to put it; 8 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.
Very hot and dry conditions in the second half of August led to rapid expansion of drought conditions in portions of Iowa.
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 22, 5:32 AM CST, 1 hour 28 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 632 AM CDT Tue Aug 22 2023 ...Updated for the 12z Aviation Discussion... .DISCUSSION.../Today through Monday/ Issued at 300 AM CDT Tue Aug 22 2023 Key Messages: - Sultry weather continues through Wednesday statewide lingering over southern and eastern Iowa into Thursday - Fleeting rain/storm chances at best Thursday night/Friday - Cooler with more seasonal temperatures next weekend Details: RAP analysis shows the center of the 500mb high pressure near Greenfield this morning with both DVN and OAX recording a 602dm 500mb height on their 00z RAOB. Impressive...and hot! The heat will continue onward with near record to record highs and high minimum temperatures today through possibly Thursday at long-term climate sites. Presently, satellite imagery has shown recently development of low clouds over northwest Iowa with the subtle hints of fog confirmed by reduced surface visibilities over northern Missouri into parts of southern Iowa. Looking back at the last several nights of the 00z HREF low cloud probability and then observations, seems it has had an overall good handle on this concept. Thus, tonight's 00z HREF low cloud probabilities and ceilings less than 3000 feet show increasing likelihood through the predawn hours and have sky cover increasing in this time frame. There is more uncertainty in the fog potential as soundings show moisture trapped beneath the inversion, but largely elevated and would lean more toward stratus. Will have to monitor satellite and surface trends and make adjustments. The clouds and any fog should lift and scatter by mid to late morning with sunshine in full force this afternoon. The 500mb high will sit over Iowa today with 850mb temperatures about 1 to 3 C warmer than yesterday across our forecast area around 27C. So highs will be higher than yesterday. However, for the last two days (Sunday and Monday), many, but not all, locations have been overforecast by on average of 2 degrees. So, while our temperature forecast is increasing, have tapered back on the initial NBM guidance this afternoon. With highs well into the 90s and dewpoints into the 70s to near 80 degrees, heat index values will be above 105 degrees. Thus, the excessive heat warning for the entire area remains valid. As a reminder, all users should be wary of AWOS sites, which can report erroneously high dewpoints and thus inaccurate heat index values. Tonight's 00z HREF once again shows low cloud probabilities from southwest into parts of central into eastern Iowa for tonight. Cloud cover that does develop will dissipate by mid-morning Wednesday. The 500mb high will start to ever so slightly weaken and drift southwestward on Wednesday. Still, 850mb temperatures will remain around 27C. A difference that could make Wednesday the warmest day is that soundings show a deeper boundary layer, which would tap into warmer and drier low level air. This will need to be closely watched as if the deeper mixing does not occur, may need to scale back temperatures similar to what occurs today. By Thursday, a shortwave trough that is currently off the British Columbia coast will be barreling eastward through the southern Canadian prairies headed toward the Great Lakes by the end of the week. This will help to push a cool front into the state by Thursday morning and through the state Thursday night. The front should bring slight relief to northern Iowa and soundings indicate at least mid- level moisture such that some clouds may aid in not as hot of conditions. For areas along and south of mainly US Highway 30, confidence is high enough in around 105 degree heat index combined with the duration of several days of dangerous heat conditions to go forward with an extension of the excessive heat warning. For areas north of there, the uncertainty previous forecast cycles has mentioned remains so have kept a watch to allow for fine tuning of the headlines along with collaboration with neighboring offices. The cooler and drier air will sink into the state Friday into this weekend as temperatures drop back to more seasonal levels by Saturday into Sunday. As for rain and storm chances Thursday night into Friday, they remain quite limited. So, while Iowa will get relief from the heat, the dry conditions will persist and offer no help to the persistent drought conditions over many parts of the state. && .AVIATION.../For the 12Z TAFS through 12Z Wednesday morning/ Issued at 632 AM CDT Tue Aug 22 2023 Over the course of the last two hours, corridors of IFR and MVFR stratus have formed and in some cases this has been in concert with IFR fog restrictions. The exception has so far been ALO, which seems to be east of the current corridor of clouds. Current expectation is for the low clouds over central Iowa to become more widespread before the fog dissipates and clouds lift and scatter by late morning. However, confidence in the exact timing and details is lower than normal. Once passed this morning, VFR conditions will prevail until perhaps late in the period where this cycle may once again play out. && .DMX WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 9 PM CDT Wednesday for IAZ004>007- 015>017-023>027-033>037. Excessive Heat Watch from Wednesday evening through Thursday evening for IAZ004>007-015>017-023>027-033>037. Excessive Heat Warning until 7 PM CDT Thursday for IAZ028-038- 039-044>050-057>062-070>075-081>086-092>097. && DISCUSSION...Ansorge AVIATION...Ansorge
Hazardous Weather Outlook National Weather Service Des Moines IA 303 AM CDT Tue Aug 22 2023 IAZ028-038-039-044>050-057>062-070>075-081>086-092>097-230815- Bremer-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- 303 AM CDT Tue Aug 22 2023 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight An Excessive Heat Warning is in effect for the area. Please refer to the National Weather Service website at weather.gov/desmoines for further details. .DAYS TWO THROUGH SEVEN...Wednesday through Monday The long duration heat event continues through Thursday with dangerous heat index values. An Excessive Heat Warning is in effect for the area through Thursday evening. Please refer to the National Weather Service website at weather.gov/desmoines for further details. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. IAZ004>007-015>017-023>027-033>037-230815- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Pocahontas-Humboldt-Wright-Franklin-Butler-Sac-Calhoun-Webster- Hamilton-Hardin- 303 AM CDT Tue Aug 22 2023 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight An Excessive Heat Warning is in effect for the area. Please refer to the National Weather Service website at weather.gov/desmoines for further details. .DAYS TWO THROUGH SEVEN...Wednesday through Monday The long duration heat event continues through at least Wednesday with dangerous heat index values. An Excessive Heat Warning is in effect for the area through Wednesday evening, with an Excessive Heat Watch in effect Wednesday evening through Thursday evening. Please refer to the National Weather Service website at weather.gov/desmoines for further details. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected.
The national radar mosaic for the moment the first event began.
8 drought. Local standard time, as filed.
Hot and dry conditions worsed in the second half of August leading to a rapid expansion of severe drought in portions of Kossuth County.
Hot and dry conditions worsed in the second half of August leading to a rapid expansion of severe drought in a small portion of Winnebago County.
Hot and dry conditions worsed in the second half of August leading to a rapid expansion of severe to extreme drought in much of Hancock County.
Hot and dry conditions worsed in the second half of August leading to a rapid expansion of severe to extreme drought in Cerro Gordo County.
Hot and dry conditions worsed in the second half of August leading to a rapid expansion of severe drought in Humboldt County.
Hot and dry conditions worsed in the second half of August leading to a rapid expansion of severe drought in portions of Webster County.
Hot and dry conditions worsed in the second half of August leading to a rapid expansion of severe to extreme drought in portions of Wright County.
Hot and dry conditions worsed in the second half of August leading to a rapid expansion of severe to extreme drought in Franklin County.
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: 1123339, 1123340, 1123341, 1123342, 1123343, 1123344, 1123345, 1123346.