A thermal ridge across much of the midwest brought the first round of summer-like temperatures to the area in early June. By late in the day a shortwave moving across the northern plains flattened the nose of the ridge a pulled a cool front across northern Iowa.
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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 thermal ridge across much of the midwest brought the first round of summer-like temperatures to the area in early June. By late in the day a shortwave moving across the northern plains flattened the nose of the ridge a pulled a cool front across northern Iowa. Convection developed along this boundary in the evening in the form of gusty winds across northern Iowa. Convection then diminished overnight as the front continued to sink south across the state. By early morning the front had made it to central Iowa where storms restrengthened, dropping large hail and producing gusty winds. By mid-morning the front had pushed south of the 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 Des Moines, IA wrote its last area forecast discussion before the first event at Jun 2, 2:01 PM CST, 3 hours 7 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 301 PM CDT Tue Jun 2 2020 .DISCUSSION.../Tonight through Tuesday/ Issued at 301 PM CDT Tue Jun 2 2020 Synoptic Overview: Broad ridge spreads across most of the central U.S. with the axis sliding across the Missouri River Valley this afternoon. Sharp short- wave trough is moving through the Dakotas this morning with surface thermal boundary placed across the Interstate 90 corridor through the northern Plains into the upper Midwest. This feature will be the focus for a severe weather threat later today. Today: On the south side of the boundary, H85 WAA will be strong today, which along with mostly clear skies will allow temperatures to jump into the lower to mid 90s through most of the CWA. Northern Iowa may actually see warmer temperatures than southern Iowa this afternoon. Expect to see moisture pooling just ahead of the boundary, which will keep dewpoints in the mid to upper 60s across northern portions of the forecast area later this afternoon. The amplified ridge across the central CONUS will begin to flatten as CVA ramps up ahead ahead of the short-wave, promoting H5 height falls across the northern Plains and upper Midwest. This will also force the surface boundary southward throughout the afternoon. This will be the feature to watch with respect to the convection and severe weather potential later this afternoon and into the evening. CAM guidance has not been providing the best consistency for convection and severe weather potential across the northern portions of the forecast area for later this afternoon through the evening. The last few cycles of the operational HRRR have backed off of intense convection over the forecast area, focusing the threat mainly in SE Minnesota and western Wisconsin this evening. However, not completely sold on this operational HRRR trend. 12z NSSL-WRF and NMM attempt to develop a cluster of multi-cells across northern Iowa after 2z this evening (and the 18z HRRRv4 has done this as well). A look at CAM soundings across the northern forecast area shows decent capping, which could potentially limit updraft development. However, these CAM soundings are generally under estimating dewpoint temperatures, by 8-10F in some of the extreme cases. Further, the boundary layer across the north has had plenty of time to destabilize. Given that several of the CAMs are coming in too low with dewpoint temperatures, the surface based CAPE values are likely closer to the maximum of the HREF members rather than the mean, which would place values closer to 4000 J/kg this afternoon. Adjusting the dewpoints in CAM soundings also yields similar CAPE values. Thus, the capping inversion noted in these soundings may not be as much of an issue if this instability continues to develop this afternoon, especially in the presence of strong convergence with the synoptic boundary in place and an outflow boundary noted on GOES satellite imagery moving southeastward from the remnant convection over the Dakotas this morning. As for the severe threat, the more favorable shear environment for Iowa does not come into play until after 01z, where 0-6 km bulk shear will be around 35-40 kts. Coupled with rather steep low and mid-level lapse rates (assuming mixing remains robust this afternoon), updrafts may be sustained over a considerable depth, thus looking for hail to be the primary threat with storms over Iowa. Damaging wind gusts up to 70 MPH could come into play, with DCAPE values between 1000-1500 J/kg. Lapse rates look to remain near dry adiabatic up to around 800 mb. If a rogue supercell thunderstorm is able to develop, an isolated tornado could be possible. But throughout this afternoon, the low-level shear environment just does not seem to be materializing for it. HREF mean 0-1 km SRH values barely touch 100 m^2 s^-2 close to time of CI. This may be very reliant on storm scale processes sharply modifying the near storm environment. Additionally, LCLs at their lowest will be around 1500 m, with several point soundings showing over 2000 m. Thus, will be looking mainly at a hail and wind threat. Due to the cap that is in place, bust potential still remains medium on the severe threat this afternoon. SE Minnesota and and western Wisconsin will have the environment with slightly less uncertainty. Should deep convection be inhibited late this afternoon, can still expect some elevated showers on the backside of the boundary, with the short-wave moving in from the Northern Plains providing enough convergence to get things going. Wednesday and Beyond: Mid-level flow becomes more zonal through the middle and end of this week. However, several small perturbations will result in modest height falls, providing chances for light showers Wednesday and early Thursday. Temperatures will remain warmer throughout the week as H85 flow quickly returns southerly, leaving the forecast area in in an area of moderate WAA. If precipitation or cloud shield remains expansive, this will limit insolation and high temperatures some throughout the week. Late Thursday into Friday morning, another short-wave trough moves across the Missouri River Valley. This short- wave will be tied better with a surface cyclone and boundary that may bring convection to the forecast area. Ahead of the surface boundary, GFS/NAM attempts paint an area in the western forecast area with surface CAPE over 3000 J/kg, along with around 40 kts of 0- 6 bulk shear, may support a severe threat. This threat is currently highlighted by the SPC Day 3 Slight Risk for severe weather. This instability will be conditional on clearing from previous shower activity. Into the weekend, the synoptic picture becomes interesting. At 500 mb, a closed 5910 m contour high begins to move northeastward off the Mexican Plateau into the southern Plains. Meanwhile, a closed low sits off the Baja Peninsula. The high off the Plateau will act as a block to the closed to low. GFS and ECMWF solutions diverge. GFS depicts a short-wave at H5 that kicks off from the Rockies over the weekend, while the ECMWF amplifies the ridge across central CONUS. Thus for the weekend, will keep limited POPs in the forecast to account for possible action within mid-level southwesterly flow. Temperatures at this time for the weekend will also be kept closed to the mean of the possible solutions, and will pinpoint better as guidance converges to a more consistent solution. && .AVIATION.../For the 18Z TAFS through 18Z Wednesday afternoon/ Issued at 1237 PM CDT Tue Jun 2 2020 Clear skies for this afternoon, with wind gusts up to 25 kts. Later this evening, rain showers and thunderstorms will develop along a cold front that will move southeastward from Minnesota. Main terminal impacts will be at MCW and ALO, although FOD and DSM will see at least rain shower activity with nearby thunderstorms. Rain showers may reduce visibilities between 5 and 6 miles, while ceilings may drop to MVFR at the terminals after the heaviest rain showers have passed. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && DISCUSSION...Krull AVIATION...Krull
Hazardous Weather Outlook National Weather Service Des Moines IA 339 PM CDT Tue Jun 2 2020 IAZ045>050-057>062-070>075-081>086-092>097-032045- 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- 339 PM CDT Tue Jun 2 2020 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight Scattered thunderstorms may occur late this evening into the overnight hours. An isolated strong to severe storm is possible with thunderstorm winds the main threat. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Intermittent thunderstorm chances remain through the period. A few severe storms are possible over far southern Iowa Wednesday. Additional strong storms may occur Thursday and Thursday night. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated. IAZ004>007-015>017-023>028-033>039-044-032045- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun- Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford- 339 PM CDT Tue Jun 2 2020 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight Strong to severe storms are expected to develop near the Iowa and Minnesota border late this evening and then settle south this into the overnight . The greatest threat is very large hail golfball sized or larger and damaging wind gusts of 60 to 70 mph with the strongest winds mainly along the Iowa Minnesota border. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Intermittent thunderstorm chances remain through the period. A few severe storms are possible Thursday and Thursday night. .SPOTTER INFORMATION STATEMENT... Spotter reports may be needed after 6 pm today. REV
The Sioux Falls radar (KFSD), 161 km away, was scanning. The volume nearest the first event began at 23:07 UTC.
5 thunderstorm wind, 3 hail, 1 heavy rain. Local standard time, as filed.
Estherville Airport ASOS reported 72 mph wind gust associated with outflow from storms well to the north.
Strong gusts of 66 mph reported at Estherville Airport ASOS well in advance of approaching thunderstorms.
Mesonet station recorded gust of 74 mph.
Mesonet reported gust of 60 mph.
Trained spotter reported a measured wind gust of 62 mph.
Public report of golf ball sized hail.
Trained spotter report of nickle sized hail.
Trained spotter reported 1.15 inches of rain in 15 minutes along with pea to dime sized hail.
Trained spotter reported quarter sized hail fell between 6:05am and 6:12am with some damage to cars.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2020Every state in 2020This day in weather historyWarnings in Iowa, June 2020
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: 895965, 895966, 895967, 895968, 895969, 895961, 895962, 895964, 895963.