Iowa remained entrenched in the relative ring of fire weather pattern. Morning convection lingered across southern Minnesota and northern Iowa through the morning, before generally subsiding.
Every event with a place to put it. 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.
Iowa remained entrenched in the relative ring of fire weather pattern. Morning convection lingered across southern Minnesota and northern Iowa through the morning, before generally subsiding. By the early afternoon though, ingredients for severe weather were well in place with a shortwave moving through the parent flow, MUCAPE values in excess of 2000-3000 J/kg, effective shear around 40 kts, and 1-3 km SRH around 200-300 m2/s2. All in all, it suggested a day with the potential for supercellular storms with all modes of severe weather possible. By the evening, as much as true with multiple funnel cloud or brief tornado touchdown reports, numerous hail reports, a couple of wind reports, and heavy rain in excess of 2 to 3 inches.
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 9, 3:14 AM CST, 1 hour 43 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 414 AM CDT Sat Jun 9 2018 .SHORT TERM.../Today through Tonight/ Issued at 414 AM CDT Sat Jun 9 2018 Rest of This Morning... Eyes will remain on the MCS nearing the Nebraska/Iowa border at 08z. Outflow boundary continues to surge ahead of the main convection. Numerous reports of 60 to 70 mph winds as this line rolled through central to eastern Nebraska. Mesoscale analysis shows best instability towards the southeast... from southeastern Nebraska into northwestern Missouri. Per SPC mesoanalysis, MLCAPE values nearing 3000 J/KG in this region... relaxing to 2000 J/KG from the Des Moines metro to Fort Dodge. Intuitively, would expect the strongest parts of this line to want to surge southeastward, towards Kansas City more so than surging eastward towards the Des Moines metro...and this solution is verified by the CAMS output. The northwestern segment of this MCS should continue to bow out northeastward and may clip the western/northwestern tier of counties in the DMX CWA. It does appear these storms should continue to remain "uncapped", but instability does look to deteriorate through 14z... which is climatologically favored. Ultimately, the best parameters are southwest of the DMX CWA... towards Kansas City, and instability should decrease as the line makes it into Iowa. Thus, am expecting severe weather to miss the DMX CWA. Worth mentioning is the fact the 07z Sat HRRR is developing a wake low behind this system. By around 13z, the HRRR places this wake low in northeastern Nebraska, and by 15z, the wake low is progged to be near Crawford county... and weakening. Will have to watch Nebraska obs for the next few hours to see if this outcome pans out... good news is we would have a few hours of "heads up" if it does occur, so we should be able to adequately issue a SPS and/or High Wind Warning with lead time. This Afternoon/Evening Into Tonight... First, will have to see how this morning's MCS evolves and progress through Iowa during the morning hours. If outflow surges through Iowa, atmosphere could be "gunked" over and maximum instability would not be realized. Regardless, thunderstorms and moderate to heavy rainfall potential exists over eastern/northeastern Iowa especially. WPC has highlighted this area with a Slight Risk. Abundant moisture across all of Iowa as PWATs are in the 1.5 to 1.75 inch range... which is a solid +1 to +2 std dev.. There are even a few pockets nearing 2 inches. Warm cloud depths crush 4km. MUCAPE values are expected to push 1500 to 2500 J/KG throughout this time period. There is very strong low-level moisture flux converge, that is well-phased with a swath of 310k isentropic adiabatic ascent. In terms of evolution, CAMs peg winds veering from the west parallel with the boundary, and support a southern push through Iowa, including the Des Moines metro, sometime Sunday evening. Timing is still touchy, with the NAM family being fast outliers. The HRRR family would push this line through the DSM metro around 01-04z Sun. Damaging winds and large hail would be the primary threats. Interestingly, BUFKIT shows a very impressive, "sickle-shaped" hodograph with this system, so will have to activate tornado potential. LCL heights should be near to under 1000m. Moderate to heavy rainfall potential exists in northeastern Iowa through midnight or so tonight. Obviously this portion of the state is reaching the point of where it cannot handle much more rain. Have held off on issuing and flood/flash flood watch products, opting to defer to the incoming shift as they should have a better handle on QPF. .LONG TERM.../Sunday through Friday/ Issued at 357 AM CDT Sat Jun 9 2018 The active weather pattern is expected to persist through Monday night before high pressure arrives Tuesday and brings a couple of quiet days to the state. Easterly flow from the area of high pressure across the Great Lakes will help keep a boundary across Iowa until Monday night when a cold front passes through the state. This will keep the instability axis across Iowa as well. The instability combined with a few more short waves yet to pass through will lead to additional rounds of thunderstorms. Any storms will carry an attendant severe weather threat though the best combination of instability and shear arrives on Monday. In addition. PWAT values of 1.75 to 2 inches will be common through Monday night along with warm cloud depths around 13 kft. Therefore, the heavy rain threat will persist as well. In addition to some flash flooding potent, will need to continue to monitor the Shell Rock and Cedar River basins as heavy rainfall has just occurred in that region and streams will already be running high. Sunday should be mostly dry though will be dependent on a potential overnight MCS evolution. A few storms could bubble in vicinity of the surface boundary though better chances should arrive Sunday night as better forcing arrives. Temperatures on Sunday remain a bit tricky with potential cloud debris lingering along with uncertainty regarding the extent of the easterly flow from the Great Lakes high pressure. The current forecast temperature range across Iowa may not be enough yet. Temperatures could range from the 70s northeast to low to mid 90s southwest. As alluded to earlier, the best chance for widespread precipitation arrives mid to late Monday afternoon and into the overnight as the surface boundary and upper level short wave arrive. Storms will have the potential for large hail and damaging winds given the strong instability, good DCAPE and high 0-3 km theta-e differences. An attendant heavy rain threat will remain. Tuesday and Wednesday will be mostly quiet and pleasant as high pressure moves into the state and the upper flow becomes zonal. The flow will transition back to ridging then southwest by the end of the week and this will bring a return to more active weather. && .AVIATION.../For the 06Z TAFS through 06Z Saturday night/ Issued at 1150 PM CDT Fri Jun 8 2018 Difficult TAF forecast. Prevailing conditions still expected to be VFR however storms late tonight then again Sat afternoon and evening may drift into KFOD, KMCW and KALO which may produce wind gusts and high end MVFR cigs. && .HYDROLOGY... Issued at 357 AM CDT Sat Jun 9 2018 As mentioned in the Long Term Section, the Winnebago, Shell Rock and Cedar River basins all had heavy rainfall over portions of basins in the past 24 hours. Potential remains for another round or two of heavy rainfall. With streams already running high, additional rainfall would likely cause additional flooding. One location to watch now is Greene along the Shell Rock as it sits below the Winnebago and Shell Rock confluence. Iowa Flood Center Gage near Marble Rock shows that the stream height has now exceeded the early May high water levels. Additional rises will likely continue into this morning. Obviously any additional heavy rainfall would have impacts on the community. The Shell Rock below Greene does tend to attenuate before reaching Clarksville and also has Flood Creek entering just southeast of Packard. Part of Flood Creek's Basin was impacted by heavy rain in Floyd county so still some uncertainty how much water is coming down stream there. Another heavy rain event across the upper Shell Rock could have big impacts. For now the Cedar Basin is will be reliant on another round of heavy rain or two before impacts occur outside of agricultural flooding. Will be collaboration with the NCRFC today and addition will consider the need for a conference call with local Emergency Managers. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM...Kotenberg LONG TERM...Donavon AVIATION...FAB HYDROLOGY...Donavon
Hazardous Weather Outlook National Weather Service Des Moines IA 441 AM CDT Sat Jun 9 2018 IAZ004>007-015-016-023>026-033>038-044>050-057>062-070>075- 081>086-092>097-100945- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Pocahontas- Humboldt-Wright-Franklin-Sac-Calhoun-Webster-Hamilton-Hardin- Grundy-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- 441 AM CDT Sat Jun 9 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight Strong to perhaps severe storms along with locally heavy rainfall will be possible from this afternoon through tonight. .DAYS TWO THROUGH SEVEN...Sunday through Friday A few thunderstorms will be possible Sunday morning then again Sunday night. Locally heavy rainfall will be possible. A more organized threat for severe weather is possible later Monday afternoon into Monday night along with locally heavy rainfall. Additional thunderstorms are possible late Wednesday through next Friday, but predictability of severe weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed at times through Monday night. IAZ017-100945- Cerro Gordo- 441 AM CDT Sat Jun 9 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight An Areal Flood Warning is in effect for much of the county with a River Flood Warning for the Winnebago River at Mason City. Please refer to our website at weather.gov/desmoines for further details. Strong to perhaps severe storms along with locally heavy rainfall will be possible from this afternoon through tonight. .DAYS TWO THROUGH SEVEN...Sunday through Friday A few thunderstorms will be possible Sunday morning then again Sunday night. Locally heavy rainfall will be possible. A more organized threat for severe weather is possible later Monday afternoon into Monday night along with locally heavy rainfall. Additional thunderstorms are possible late Wednesday through next Friday, but predictability of severe weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed at times through Monday night. IAZ027-028-039-100945- Butler-Bremer-Black Hawk- 441 AM CDT Sat Jun 9 2018 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...Today and tonight Expect rises along the Shell Rock and Cedar River basins along with some flooding in the Greene area. Additional heavy rainfall could lead to increased flooding along these streams. Strong to perhaps severe storms along with locally heavy rainfall will be possible from this afternoon through tonight. .DAYS TWO THROUGH SEVEN...Sunday through Friday A few thunderstorms will be possible Sunday morning then again Sunday night. Locally heavy rainfall will be possible. A more organized threat for severe weather is possible later Monday afternoon into Monday night along with locally heavy rainfall. Additional thunderstorms are possible late Wednesday through next Friday, but predictability of severe weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed at times through Monday night.
Special Weather Statement
National Weather Service Des Moines IA
425 AM CDT SAT JUN 9 2018
IAZ044-045-057-058-070-071-081-092-091015-
Guthrie IA-Audubon IA-Adams IA-Adair IA-Carroll IA-Crawford IA-
Taylor IA-Cass IA-
425 AM CDT SAT JUN 9 2018
...Line of Thunderstorms May Produce Winds to 50 mph...
At 424 AM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 8 miles east of Ute to Farragut. Movement was
east at 65 mph.
Wind gusts up to 50 mph will be possible with these storms.
Locations impacted include...
Carroll, Denison, Atlantic, Audubon, Corning, Bedford, Manning, Coon
Rapids, Glidden, Dunlap, Griswold, Lake Icaria, Anita, Schleswig,
Exira, Adair, Manilla, Elk Horn, Dow City and Charter Oak.
LAT...LON 4058 9492 4116 9493 4116 9516 4150 9515
4151 9504 4160 9504 4160 9509 4186 9509
4186 9561 4220 9562 4219 9465 4057 9466
TIME...MOT...LOC 0924Z 290DEG 56KT 4209 9555 4070 9550
KotenbergThe Des Moines radar (KDMX), 149 km away, was scanning. The volume nearest the first event began at 10:56 UTC.
11 hail, 4 funnel cloud, 3 heavy rain, 3 flash flood, 2 flood, 1 thunderstorm wind. Local standard time, as filed.
Flooding continued along the Shell Rock River with all campgrounds near Clarksville closed including Henry Woods State Park and Shell Rock Park due to flooding. A few businesses along the river were impacted as well.
CoCoRaHS observer recorded heavy rainfall of 2.22 inches over the last 24 hours.
Coop observer recorded heavy rainfall of 2.72 inches over the last 24 hours.
Coop observer recorded heavy rainfall of 3.70 inches over the last 24 hours.
Public reported a funnel cloud along Highway 9 between Buffalo Center and Thompson.
Public reported a funnel cloud.
Trained spotter reported up to 2.5 inch diameter hail.
Public reported up to 2 inch diameter hail.
Public reported a funnel cloud.
Public reported ping pong ball sized hail.
Mason City ASOS, near Clear Lake, recorded a 71 mph wind gust.
Public reported penny sized hail.
Trained spotter reported several roads in town reportedly under 1 to 2 feet of water.
Trained spotter reported culverts are overwhelmed with water already covering half of the outside lines on Highway 65 at this location.
Trained spotter reported several quick funnels with a rapidly rotating wall cloud.
Emergency manager reported penny sized hail.
KWWL relayed a public report of quarter sized hail.
Iowa DOT reported US Highway 65 closure due to water over the roadway near mile marker 200.
CoCoRaHS observer reported golf ball sized hail.
Public reported nickel to quarter sized hail.
Trained spotter reported nickel sized hail accompanied by heavy rain.
Trained spotter reported mostly pea to nickel sized hail with a few to the size of quarters.
Public reported nickel sized hail.
Law enforcement reported flooding of various streets in and around Mason City, with creeks at bankfull or flooding areas in and around the city as well.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2018Every state in 2018This day in weather historyWarnings in Iowa, June 2018
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: 767236, 761839, 761840, 761841, 761807, 761808, 761810, 761811, 761812, 761813, 761814, 761815, 761817, 761823, 761826, 761828, 761829, 761830, 761831, 761834, 761835, 761836, 761837, 767251.