A PV anomaly entering the region and associated surface boundary interactions, with increasing forcing overhead and favorable deep layer shear, resulted in scattered on and off showers and thunderstorms throughout much of the day. This resulted in a handful of severe wind reports and isolated wind damage, particularly in Clarke and Marshall counties with gusts generally ranging between 60 to 70…
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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.
A PV anomaly entering the region and associated surface boundary interactions, with increasing forcing overhead and favorable deep layer shear, resulted in scattered on and off showers and thunderstorms throughout much of the day. This resulted in a handful of severe wind reports and isolated wind damage, particularly in Clarke and Marshall counties with gusts generally ranging between 60 to 70 mph.
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 Jul 10, 11:42 AM CST, 37 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Des Moines IA 1242 PM CDT Wed Jul 10 2024 ...Updated for the 18z Aviation Discussion... .KEY MESSAGES... - Scattered thunderstorms today. Marginally severe storms possible. A few funnel clouds also possible - Quiet Thursday and Friday. - Heat returns on Sunday with heat indicies in the 100-105 range over parts of the area. && .DISCUSSION... Issued at 401 AM CDT Wed Jul 10 2024 The remnants of Beryl have are now near the southern tip of Lake Michigan with the last impacts over Iowa now are just some lingering clouds over the far eastern portion of the state. Another system with a robust PV anomaly consisting of a short wave cluster, is moving southeast through western Minnesota and eastern South Dakota with showers and a few thunderstorms descending south/southeast towards northwest Iowa. This system will continue to move into and across Iowa today and will be accompanied by attendant thunderstorm chances. A few features of note today. Convective temperatures are relatively low and in the upper 70s to low 80s in large part due to cooler temperatures a loft. These temperatures should be well within reach given that the mid level clouds do not fill in more than what has already occurred. This means that convection should be easily triggered given the kinematic forcing passing through. A few landspout funnels are possible today with a couple slow moving boundaries with little flow near it along with good stretching potential and surface vorticity in vicinity of the boundary. One boundary should be over northeast to north central Iowa this afternoon. That region will be a very low deep layer shear area where the potential for any organized activity is low but it may be the more favored region for any landspout funnels. The other boundary will be over central into west central/southwest Iowa. This region will have a bit more deep layer shear with some speed and directional shear available. Several CAMs are suggesting wind gusts and outflow with some of these storms. In addition, marginally severe hail could occur. The activity will linger into this evening then ending from north to south. A couple relatively quiet days will follow to end the work week as high pressure ridge is the main weather influence. Thursday will have light winds with conditions becoming more breezy on Friday as the wind turns more southerly. A large upper level high will be entering the intermountain west this weekend and will lead to warm advection into the state. The warmest air will arrive Saturday night and into Sunday and as this occurs, expected an Elevated Mixed Layer to develop and become more pronounced. The NBM temperatures on Saturday are near the 75th percentile and for Sunday it is over the 90th percentile with highs in the low to mid 90s. The NBMs track record through June has been way too optimistic in forecasting potential heat events and often has been several degrees too warm in the day 3-5 timeframe. This looks like another potential period of the NBM being too warm. Dew points will be on the increase and in the upper 60s and 70s. The Iowa corn crop should be entering peak evapotranspiration soon and given the relatively wet top soil, it should be efficient. This will pump a lot of water into the air which requires more energy to heat and thus likely leading to lower high temperatures. Finally, the ECMWF and GFS ensemble highs for Sunday are 4-7 degrees cooler than deterministic MOS guidance for Sunday. Therefore, have cooled highs a bit for Sunday. It is still a potential day with near headline criteria heat indicies fueled by higher dew points despite potential lower temperatures. Will the warmer weather persist into Monday is in question, pending on how quickly that western upper high and the associated westerlies into Iowa buckled as a system moves into the Midwest. Beyond that, upper ridging to the west could be setting up a ring of fire with storms running the lee side of the ridge, which often turns into damaging wind events somewhere. Finally of note is potential Canadian fire smoke moving into Iowa during periods of northwest flow aloft. Today is one day as a patch of smoke moves over Iowa. More chances of smoke filtered skies may arrive next week with that potential upper ridge to the west. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1241 PM CDT Wed Jul 10 2024 Scattered showers/storms over the area through about 01z with higher chances at ALO/FOD/DSM/OTM. Upper level wave tracking south with sfc trough expected to move south of the region aft 06z. Main challenge timing/coverage but some storms will lower cigs to MVFR with vsby 2-5sm possible with brief heavy downpours. Patchy fog also expected 10-13z. Aft 13z, remainder of period fairly benign. /rev && .DMX WATCHES/WARNINGS/ADVISORIES... None. && DISCUSSION...Donavon AVIATION...REV
Hazardous Weather Outlook National Weather Service Des Moines IA 343 AM CDT Wed Jul 10 2024 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097-111100- 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- 343 AM CDT Wed Jul 10 2024 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight Scattered thunderstorms are expected today. A few marginally severe storms are possible with gusty winds and small hail. Locally heavy downpours remain possible as well. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Heat builds into the weekend and early next week with heat index values approaching or exceeding 100 by Sunday and Monday. .SPOTTER INFORMATION STATEMENT... Spotter activation is unlikely at this time.
The Des Moines radar (KDMX), 80 km away, was scanning. The volume nearest the first event began at 18:17 UTC.
3 thunderstorm wind. Local standard time, as filed.
Measured wind gust of 62mph, with 1 to 2 inch limbs broken off trees. Nearly an inch of rain in 30 minutes.
Tower blown down at dispatch office in Clarke county. Numerous trees in Osceola of 14-16 diameter also damaged. Estimated winds of 60 to 70 mph.
No damage has been reported with this wind gust.
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: 1199521, 1199523, 1199524.