Thunderstorms developed in central Iowa and moved across eastern Iowa during the late afternoon and evening hours of July 10th. These storms produced damaging winds and heavy rainfall across the area.
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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 DVN wrote it up.
Thunderstorms developed in central Iowa and moved across eastern Iowa during the late afternoon and evening hours of July 10th. These storms produced damaging winds and heavy rainfall across the area. Heavy rain led to flash flooding as the storms moved into the Iowa City metropolitan area.
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 Quad Cities, IA wrote its last area forecast discussion before the first event at Jul 10, 11:53 AM CST, 37 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Quad Cities IA IL Issued by National Weather Service La Crosse WI 1253 PM CDT Wed Jul 10 2024 .KEY MESSAGES... - There is a chance (40-60%) of scattered showers and thunderstorms this afternoon/evening. An isolated severe storm or two will be possible with heavy downpours, gusty winds, and funnel clouds the main threats. - Increasingly humid Friday and into next week. Heat indices well into the 90s and even low 100s are forecast Sunday and Monday. - Moderate to major river flooding continues on the Mississippi River with most sites crested or cresting in the coming days. && .SHORT TERM /THROUGH THURSDAY NIGHT/... Issued at 320 AM CDT Wed Jul 10 2024 MSAS surface analysis and water vapor imagery early this morning show the surface low that was previously tropical depression Beyrl was centered over north central IN. Radar mosaics depict the back edge of the showers finally just to our east. Very weak flow aloft (under 15 kts up to 600mb) and some dry mid levels were seen on our 00z DVN sounding. In contrast just to our south on the 00z ILX sounding showed 30kts of mid level flow and a nearly saturated profile with 1.82" precipitable water! A mild start to the day is expected with temperatures and dewpoints in the mid to upper 60s with clearing skies. Attention then turns to the shortwave diving south out of MN into IA. This wave is currently supporting showers/storms in western MN and eastern SD. This Afternoon/Evening...with a mild start and high sun angle expect instability to build as we warm up today. Forecast soundings and spatial progs show CAPE values in the 1200-1900 J/Kg range with PWs in the 1.3-1.5" range. The limiting factor for organized severe weather remains meager deep layer and low level shear. However, the diving shortwave may be able to augment the kinematics enough that a few severe storms may still be possible. Main threats would be marginally severe wind and heavy downpours in the strongest cells. The 00z HREF 75th percentile 1-hr QPF field has rainfall rates over 0.75"/hr in the strongest storms and with slow movement, I wouldn't rule out a quick 1 inch of rain. In addition, the RAP13 NST progs up to 1.5 and with a very subtle weak boundary across the area may allow for funnel clouds this afternoon/evening. Something later shifts will have to monitor. Regarding timing, the CAM consensus and hi-res ensemble data would see convection develop around 18-19z and last until the 23-00z time frame. Tonight...any storms will quickly dissipate after sunset and loss of heating. Any clearing of clouds may allow for some fog to develop in the weak low level convergent flow, but have left out of the forecast for now. Overnight low temperatures, will only drop into the low to mid 60s. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Issued at 320 AM CDT Wed Jul 10 2024 Thursday...an elevated boundary may allow for some lingering showers to develop in northeast MO, southeast IA, and west central IL early AM. Otherwise, subsidence behind departing shortwave will bring dry conditions for the rest of the day for most. Some models are still hinting at some diurnal showers/storms, but feel this activity may remain just to our south and east. Friday-Saturday...return flow develops as high pressure slides to our east. Model 1000-500mb RH progs suggest that most of the area will be dry Friday even though it will feel quite humid outside. Another wave will top the western ridge and move into the northern Great Plains Saturday. Have maintained low slight chance/chance PoPs Saturday for diurnally driven storms. Highs Friday and Saturday will be in the mid to upper 80s. Sunday-Monday...building western ridge will advect warmer 850mb temps into the region with 850mb temps rising into the 23-26C range. This will boost temps into the 90s and combined with dewpoints in the low 70s (perhaps even higher due to mature corn crop), will push afternoon heat indices into the upper 90s and low 100s. Taking a look at the 00z ensemble data, the probability of 100 degree heat indices or greater has increased into the 50-70% range south of I-80 on Monday. This may require a heat headline if trends continue. The failure mode to this occurring would be convective debris clouds from a southward propagating MCS into our area. It is indeed the time of year for MCS tracks to ruin the forecast temps and subsequent humidity. Something also interesting to note is the CSU machine learning severe weather probabilities are highlighting much of the upper Midwest for a risk of severe weather Sunday and Monday. This will be something to monitor in later forecasts. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1242 PM CDT Wed Jul 10 2024 Aviation concerns over the next 24 hours focus on thunderstorms this afternoon and fog early Thursday morning. Probability appears to be great enough (50% or greater) to introduce TEMPO groups at each site. Similarly, with near surface moisture from showers and thunderstorms a good bet and winds becoming near calm late tonight, have gone with a short period of MVFR fog at each site as sunrise approaches. && .HYDROLOGY... Issued at 124 PM CDT Mon Jul 8 2024 Precipitation in the next few days, especially in Iowa, is expected to be dry or very light. Thus, routed flow will continue on all of our rivers. The Mississippi River is currently cresting at major levels upstream of Camanche, IA, and near crest through Illinois City. The crest may take 1 to as much as 3 days to pass. From Le Claire to Burlington, the respective crests will commence within the next 1 to 2 days. Keokuk is now forecast to crest within Moderate Flood category beginning Friday. Gregory Landing is forecast to remain near 19.5 feet through the week. Tributary Rivers: The Cedar River at Cedar Rapids crested below flood stage and will fall over the next several days. On the Cedar River at Conesville, minor flooding will continue. It will see a secondary crest near 14.4 feet Wednesday night into Thursday. The Wapsipinicon River at Dewitt is forecast to remain in moderate flooding category through late on Friday. The Iowa River at Oakville is seeing high water levels due to backwater affects from the Mississippi River. It is forecast to remain near 11.4 or 11.5 feet through midweek and then rise to near 12.1 feet late Thursday into Friday. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && SHORT TERM...Gross LONG TERM...Gross AVIATION...ARX/77 HYDROLOGY...Gunkel
Hazardous Weather Outlook National Weather Service Quad Cities IA IL 839 AM CDT Wed Jul 10 2024 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-111100- Buchanan-Delaware-Dubuque-Benton-Linn-Jones-Jackson-Iowa-Johnson- Cedar-Clinton-Muscatine-Scott-Keokuk-Washington-Louisa-Jefferson- Henry IA-Des Moines-Van Buren-Lee-Jo Daviess-Stephenson-Carroll- Whiteside-Rock Island-Henry IL-Bureau-Putnam-Mercer-Henderson- Warren-Hancock-McDonough-Scotland-Clark- 839 AM CDT Wed Jul 10 2024 This Hazardous Weather Outlook is for portions of north central Illinois...northwest Illinois...west central Illinois...east central Iowa...northeast Iowa...southeast Iowa and northeast Missouri. .DAY ONE...TODAY AND TONIGHT Scattered thunderstorms are expected this afternoon and evening. An isolated severe storm is possible with gusty winds, hail, heavy rain, and lightning the main threats. In addition, funnel clouds may occur this afternoon and evening. There is a Marginal Risk, or level 1 out of 5, for severe storms this afternoon and evening generally along and west of the Mississippi River. Area rivers are experiencing flooding. Please see the latest Flood Statements and Flood Warnings for details. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY Thunderstorms are possible Thursday and Saturday. Severe weather is not anticipated. Hot and humid conditions will be seen Sunday and Monday. Afternoon heat index values in the upper 90s to low 100s are expected. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon and evening. GENERAL STORM MOTION OF THE DAY: Toward the southeast at 20 mph. Gross/12
Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
741 AM CDT Wed Jul 10 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0152 PM Tstm Wnd Dmg Argyle 40.53N 91.57W
07/07/2024 Lee IA Public
Mobile home roof partially removed. Carport
and shed destroyed. Tree limbs down. Public
report via social media.
&&
RP KinneySpecial Weather Statement
National Weather Service Quad Cities IA/IL
Issued by National Weather Service La Crosse WI
111 PM CDT Wed Jul 10 2024
IAZ040-101900-
Buchanan IA-
111 PM CDT Wed Jul 10 2024
...A strong thunderstorm will impact portions of Buchanan County
through 200 PM CDT
...
At 111 PM CDT, Doppler radar was tracking a strong thunderstorm over
Independence, moving southeast at 20 mph.
HAZARD...Winds in excess of 40 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could cause minor tree limb damage and blow
around unsecured objects. Minor damage to outdoor objects
is possible.
Locations impacted include...
Independence, Winthrop, Quasqueton, Rowley, Monti, Buchanan County
Fairgrounds, Winthrop Golf Course, Otterville, Wapsipinicon Golf
Course, and Independence Airport.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4250 9161 4247 9161 4247 9160 4233 9160
4230 9161 4230 9193 4242 9204 4259 9193
TIME...MOT...LOC 1811Z 296DEG 16KT 4246 9185
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH
EMSThe Quad Cities radar (KDVN), 144 km away, was scanning. The volume nearest the first event began at 18:29 UTC.
2 flash flood, 1 thunderstorm wind. Local standard time, as filed.
A trained spotter estimated 40 to 50 MPH winds with 6 to 8 inch diameter branches down.
Dispatch Center reported knee depth water on 20th Avenue. The time of the event was estimated using radar.
Dispatch Center reported knee deep water on Johnson Street in downtown Iowa City. The time of the event was estimated using radar.
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, July 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: 1200300, 1200298, 1200299.