A storm system pushed a cold front across eastern Iowa during the evening hours of August 10th. 50 inches in diameter across parts of eastern Iowa.
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 DVN wrote it up.
A storm system pushed a cold front across eastern Iowa during the evening hours of August 10th. Showers and thunderstorms developed ahead of this front and produced wind gusts up to 60 MPH and hail up to 1.50 inches in diameter across parts of eastern Iowa. Rainfall mounts ranged from a few hundredths of an inch to isolated reports over one inch.
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 Aug 10, 11:39 AM CST, 1 hour 23 minutes earlier.
Area Forecast Discussion National Weather Service Quad Cities IA IL 1239 PM CDT Thu Aug 10 2017 ...AVIATION UPDATE... .SYNOPSIS... Issued at 330 AM CDT Thu Aug 10 2017 Analysis at 3 AM CDT shows lots of mid clouds ahead of a weak cool front to pass this afternoon. Some isolated showers and storms with best forcing north of the forecast area based on 3 hour pressure rise fall couplets and weak low pressure track. Upstream energy shows more northwest flow to keep region at or below normal and dry for the next several days after frontal passage this afternoon. && .SHORT TERM...(Today and Tonight) ISSUED AT 330 AM CDT Thu Aug 10 2017 Short Term Forecast Confidence Assessment...fair or average. Main issues are: first, how much clearing later today as front approaches, impacts and highs today, third is initiation of convection mid afternoon timing and coverage. Today...trends and analysis shows generally partly sunny skies with southwest winds of 10 to 20 mph by late morning. Highs should reach 80 to 87 from NE to SW. This supports convective temperature reached around 3 PM with convection along and ahead of a slowly weakening front. Local calculations at 4 PM suggest T/TD of 85/65 will result in SBCAPE in 2000+ J/KG. This yields using HELP algorithm for max hail around to just of 1.25" suggested. For winds, the BLEP algorithm suggests 40 up to 55 mph or near threshold for damaging winds. These suggest marginal risk by SPC is reasonable. If surface winds are SW then tornado threat is low to NIL due to limited BL shear and high cloud bases. Coverage of clouds with weakening front and marginal moisture levels of 40% late PM into early evening area reasonable. Area PW values of around 1.25" suggest any storms moving at 25 to 30 MPH may result in localized rain totals of .25 to .75 inches so no significant water impacts. Keep in mind the area does need the significant rains, especially south 1/3 where drought is developing and impacting area crops. Tonight...a broken line of showers and storms should slide east by mid to late evening with some strong storms possibly until mid evening. Then clearing and cooler as drier air moves in with mins by morning upper 50s NW to lower 60s southeast. .LONG TERM...(Friday through next Wednesday) ISSUED AT 330 AM CDT Thu Aug 10 2017 Friday...A post-frontal day as a llvl anticyclone dumps down the upper MS RVR Valley and toward the southwestern GRT LKS. Incoming high pressure gradient and steepening llvl lapse rates to make for a sfc wind increase form the northwest to 10-20 MPH Fri afternoon. The extent of wrap-around stratocu, or ambient renewed CU development still being handled differently by several models, ranging from a mostly cloudy deck acrs at least the northeastern half of the DVN CWA, to mostly sunny skies even in the northeast all day. Will go with a somewhat toned down NAM CU rule that suggests CU of broken deck coverage to develop by midday acrs the northeastern third to half of the DVN CWA, with it then starting to mix out to scattered levels mid to late afternoon with in-building dry subsiding vertical column. Will also keep a dry fcst going with little chance for embedded showers to develop in the enhanced cumulus fields. As for high temps, will side with mid 70s under areas that are impacted more by higher cloud cover, to the lower 80s in the southwest. Clear out and a sfc wind decouple with dry-down mixed sfc DPTs/ongoing dry sfc layer, will make for a seasonably cool night Fri night into early Sat morning with widespread lows well down in the 50s. Some upper 40s possible again in favored cool air drainage locations. Saturday and Sunday...The weekend still looks mainly dry with re- enforcing bouts of high pressure down the western GRT LKS, shunting baroclinic storm track from acrs the central/southern plains to the lower to mid MS RVR Valley regions. Just some passing bouts of high debris clouds spilling in from the west at times, along with below normal temps in the 70s to low 80s. Overnight lows continue down in the 50s as long as the cirrus is thin enough...decent diurnal swings in ongoing dry sfc layer/drought conditions. For now will ignore the new 00z ECMWF that is advertising a band of elevated showers moving eastward acrs the southern third to quarter of the CWA Sunday into Sunday evening, secondary precip action as compared to a more organized system pushing acrs the deep Ozarks. Monday through next Wednesday...Latest run medium range solutions suggest a varying strength acrs much of the central CONUS early to mid next week, which is essentially a continued dry pattern for the local area. Temp regime will look to moderate back to normal levels for that time of August by next Tue and Wed, especially high temps during the daytime. The drought will thus look to worsen with time next week. ..12.. && .AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon) ISSUED AT 1235 PM CDT Thu Aug 10 2017 Cold front to move through eastern Iowa and northern Illinois through 03z/11. TSRA are expected to develop along and ahead of the front with the potential for a period of MVFR/IFR conditions. Outside of the SHRA/TSRA expect VFR conditions. After 06z/11 there is a potential for MVFR cigs to move into eastern Iowa and possibly northern Illinois in the wrap around clouds from the departing storm system. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && SYNOPSIS...Nichols SHORT TERM...Nichols LONG TERM...12 AVIATION...08
Hazardous Weather Outlook National Weather Service Quad Cities IA IL 406 AM CDT Thu Aug 10 2017 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-110915- 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- 406 AM CDT Thu Aug 10 2017 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 This afternoon...scattered thunderstorms are expected to develop around 4 PM ahead of a weak cool front, mostly along and east of the Mississippi River. The strongest storms may approach severe levels with hail 1 inch or more the main risk, with gusty winds of 40 to 55 mph with isolated 60 mph possible a secondary risk. These storms should move east of the region by mid evening. The Storm Prediction Center has the outlook area under a marginal risk for severe storms this afternoon. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed in spotty locations, mostly between 4 and 8 PM this afternoon. Please report any severe weather or near severe weather to this NWS forecast office. Nichols/12
Special Weather Statement National Weather Service Quad Cities IA/IL 1243 PM CDT THU AUG 10 2017 IAC011-095-101830- Benton-Iowa- 1243 PM CDT THU AUG 10 2017 ...A STRONG THUNDERSTORM WILL AFFECT BENTON AND NORTHERN IOWA COUNTIES UNTIL 130 PM CDT... At 1242 PM CDT, a strong thunderstorm was located near Belle Plaine, or 10 miles southeast of Toledo, moving east at 40 mph. Winds in excess of 30 mph and dime size hail are possible with this storm. Locations impacted include... Marengo, Williamsburg, Belle Plaine, Atkins, Walford, Shellsburg, Newhall, Blairstown, Van Horne, Keystone, Norway, Ladora, Luzerne, Amana, Conroy, Middle Amana, Upper South Amana, East Amana, Hannen Lake Park and Koszta. This includes Interstate 80 in Iowa between mile markers 218 and 229. Frequent cloud to ground lightning is occurring with this storm. Lightning can strike 10 miles away from a thunderstorm. Seek a safe shelter inside a building or vehicle. This storm may intensify, so be certain to monitor local radio stations and available television stations for additional information and possible warnings from the National Weather Service. LAT...LON 4213 9230 4213 9184 4164 9183 4174 9230 TIME...MOT...LOC 1742Z 282DEG 33KT 4191 9240 RP KINNEY
Special Weather Statement
National Weather Service Quad Cities IA/IL
136 PM CDT THU AUG 10 2017
IAC095-103-101915-
Johnson-Iowa-
136 PM CDT THU AUG 10 2017
...A STRONG THUNDERSTORM WILL AFFECT JOHNSON AND NORTHEASTERN IOWA
COUNTIES UNTIL 215 PM CDT...
At 136 PM CDT, a strong thunderstorm was located near Amana, or 10
miles southeast of Marengo, moving east at 30 mph.
Winds in excess of 40 mph and half inch hail are possible with this
storm.
Locations impacted include...
Iowa City, Coralville, North Liberty, Williamsburg, Solon, Tiffin,
Lone Tree, University Heights, Swisher, Oxford, Hills, Shueyville,
Oakdale, Amana, Lake Macbride State Park, Conroy, Newport, Middle
Amana, Frytown and Windham.
This includes the following highways...
Interstate 80 in Iowa between mile markers 220 and 253.
Interstate 380 between mile markers 1 and 11.
Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
LAT...LON 4186 9197 4186 9137 4142 9137 4142 9142
4145 9150 4147 9151 4148 9150 4150 9151
4150 9152 4151 9153 4151 9164 4167 9202
TIME...MOT...LOC 1836Z 287DEG 25KT 4173 9190
RP KINNEYSpecial Weather Statement
National Weather Service Quad Cities IA/IL
139 PM CDT THU AUG 10 2017
IAC055-061-105-113-101930-
Dubuque-Jones-Delaware-Linn-
139 PM CDT THU AUG 10 2017
...A STRONG THUNDERSTORM WILL AFFECT SOUTHWESTERN DUBUQUE...JONES...
SOUTHEASTERN DELAWARE AND NORTHEASTERN LINN COUNTIES UNTIL 230 PM
CDT...
At 139 PM CDT, a strong thunderstorm was located over Waubeek, or 8
miles west of Anamosa, moving east at 40 mph.
Winds in excess of 40 mph and nickel size hail are possible with this
storm.
Locations impacted include...
Anamosa, Monticello, Cascade, Central City, Springville, Hopkinton,
Onslow, Prairieburg, Center Junction, Waubeek, Stone City, Viola,
Whittier, Langworthy, Canton, Paris, Fillmore, Linn County
Fairgrounds, Pinicon Ridge Park and Monticello Municipal Airport.
Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
LAT...LON 4208 9090 4204 9152 4223 9159 4235 9129
4242 9090
TIME...MOT...LOC 1839Z 256DEG 34KT 4215 9145
RP KINNEYSpecial Weather Statement
National Weather Service Quad Cities IA/IL
159 PM CDT THU AUG 10 2017
ILC085-IAC061-101945-
Jo Daviess-Dubuque-
159 PM CDT THU AUG 10 2017
...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN JO DAVIESS AND
CENTRAL DUBUQUE COUNTIES UNTIL 245 PM CDT...
At 159 PM CDT, a strong thunderstorm was located over Peosta, or 10
miles west of Dubuque, moving east at 35 mph.
Winds in excess of 40 mph and dime size hail are possible with this
storm.
Locations impacted include...
Dubuque, Galena, Asbury, Epworth, East Dubuque, Peosta, Menominee,
Centralia, Sageville, Bankston, Durango, Graf, Dubuque Regional
Airport, Bankston Park, Rockdale, Lattnerville, Dubuque County
Fairgrounds, Center Grove, Camp Little Cloud and Swiss Valley Park.
Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
LAT...LON 4254 9064 4251 9064 4251 9041 4233 9042
4238 9047 4238 9066 4237 9067 4242 9098
4256 9099 4258 9068
TIME...MOT...LOC 1859Z 270DEG 31KT 4247 9089
RP KINNEYThe Quad Cities radar (KDVN), 86 km away, was scanning. The volume nearest the first event began at 19:02 UTC.
9 hail, 5 thunderstorm wind. Local standard time, as filed.
The emergency manager reported a tree down in the center of town. The time of the event was estimated using radar.
A public report of 60 MPH wind gust from a thunderstorm.
The time of the event was estimated using radar.
An amateur radio operator reported trees down near the intersection of County Road G36 and Spruce Avenue.
A trained spotter estimated a thunderstorm wind gust of 40 to 60 MPH. Several small branches were blown down and nickel hail was falling at their location.
An off duty NWS employee relayed a public report of 1.5 inch hail. The time of the event was estimated using radar.
A member of the public reported 2 large tree branches down. 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 2017Every state in 2017This day in weather historyWarnings in Iowa, August 2017
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: 714710, 714682, 714733, 718962, 714683, 714725, 714735, 714684, 714685, 714686, 714687, 714707, 714708, 714732.