A low pressure system developed off the Rockies in the Wyoming, Nebraska, South Dakota region and deepened as it moved eastward through South Dakota through the day on the March 6th. Southerly flow had already established itself and was bringing up Gulf of Mexico moisture into the Plains.
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.
A low pressure system developed off the Rockies in the Wyoming, Nebraska, South Dakota region and deepened as it moved eastward through South Dakota through the day on the March 6th. Southerly flow had already established itself and was bringing up Gulf of Mexico moisture into the Plains. A dry line also developed out ahead of the parent cold front, sparking initial storms in eastern Nebraska during the afternoon hours. Storms relatively quickly developed into a linear system, though a few isolated storms developed out ahead of the main line and proceeded to produce severe hail. As the line of storms progressed eastward through Iowa, they produced numerous severe hail and damaging wind reports. Additionally, a few tornadoes developed along the line, producing damage primarily in central and southern Iowa.
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 Mar 6, 4:02 PM CST, 3 minutes earlier.
Area Forecast Discussion National Weather Service Des Moines IA 402 PM CST Mon Mar 6 2017 .SHORT TERM.../Tonight/ Issued at 312 PM CST Mon Mar 6 2017 Confidence: Medium to High Main concerns ongoing wind and severe weather. Strong winds will into the evening hours over the west/central and relax late evening. As front moves east tonight winds will increase over the west and northwest areas through the overnight hours. Severe threat already well spelled out with watch covering the entire area through late evening. Fast moving storms...damaging thunderstorm winds and hail as well as potential for isolated tornadoes due to either quasi linear bowing segments or initially a few discrete cells. Activity over western Iowa may weaken with strong shear this evening with another area of development taking place over Missouri and moving into southeast Iowa around and after 00z...mainly from I35 east. With a fast moving and fluid evolution of storms anticipated... confidence on coverage over the entire area still limited. May be more scattered in nature at times...with one or more lines of storms during the event. Winds briefly drop off a bit late tonight only to increase again on Tuesday over much of the region. .LONG TERM.../Tuesday through Monday/ Issued at 312 PM CST Mon Mar 6 2017 Tuesday the forecast concern revolves around wind. Forecast soundings mix the atmosphere to around 500mb but slightly lower than they did yesterday and winds are just a bit less. Further analysis in BUFKIT shows winds not really reaching high wind warning criteria...though very close. A wind advisory for high end wind speeds was issued for Tuesday afternoon across areas North of a line from Carrol to Waterloo. Strongest winds are expected in the far Northwest and North near the Minnesota border. There are also fire weather concerns, discussed in a separate section below. On Wednesday we will be in strong cold advection in a rather fast Northwest flow aloft. This will bring in colder temps and once again create a strong wind scenario. Given the numerous headlines in place I have opted to not include any mention of strong winds for Wednesday at this point but they are indeed going to have to be addressed in later periods. Beyond Wednesday, the overall pattern has not changed and we remain in a broad NW flow but a Canadian surface high slides down bringing a reinforcing shot of cold air. We are still looking at a couple of weak shortwaves riding through the state Friday afternoon/night and a stronger one Saturday. Yet another wave passes through in the series on Sunday/Sunday night. Given the colder temps, precip...especially at night and early morning...will likely be snow North, rain South and a mix somewhere in between. There is the possibility that accumulating snow will occur across Northern Iowa. This will be the next concern to watch for after the wind/fire threat. && .AVIATION.../For the 18Z TAFS through 18Z Tuesday afternoon/ Issued at 1204 PM CST Mon Mar 6 2017 Several concerns this period. Main the wind through this evening and again on Tuesday. LLWS will also increase by 00z tonight over the region and continue at least through 10z many locations. Second concern will be convection. Sct strong thunderstorms possible from 20z to 03z over the area...with best coverage over the south/northeast sites at KDSM/KOTM/KALO. Hires models suggest pulse storms over western Iowa initially with line taking shape near I35 around 00-01z then moving east through area by 05-06z. With coverage in question...have generally indicated with VCTS but have cat thunder at KOTM where line should be most robust between 00 and 03z. Severe wind gusts possible with line though confidence on at any site remains low at this time. Winds increase again aft 15z Tuesday with strong northwest winds most areas...gusts once again above 40kts north. && .FIRE WEATHER... Issued at 312 PM CST Mon Mar 6 2017 Very strong wind is expected over the state on Tuesday. Trends from soundings are just slightly less from yesterday's run but are still very strong. Areas North of Highway 20 are still going to see the strongest winds with more marginal wind speeds the further South you go. Calls were made to observers and core partners regarding the consideration of a red flag warning. The issue is that the strongest winds are not co-located with the lowest relative humidity values and the RH values across the North are 35 to 45% which are pretty high when considering a red flag warning. Countering that is the fact that these are one hour fuels and the strength of the wind will dry things out fairly quickly. Observers confirmed that fuels near the ground are moist and that there is some green up of cool season grasses as well as some new growth of warm season grasses beginning. Given the time of year and the lack of any activity due to the wind, cooler temps and high end advisory type wind speeds, a fire weather watch was issued. Should winds be stronger and relative humidity values across the North drop further, a red flag warning would need to be issued. I'll leave this for the mid shift to consider when the latest data is available. && .DMX WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch Tuesday afternoon for IAZ004>007-015>017- 023>028-033>039-044>050-059>062-074-075. Wind Advisory until midnight CST tonight for IAZ004>007-015>017- 023>026-033>037-044>049-057>061-070>074-081>085-092>096. Wind Advisory from 11 AM to 6 PM CST Tuesday for IAZ004>007- 015>017-023>028-033>037-044>047. && SHORT TERM...REV LONG TERM...FAB AVIATION...REV FIRE WEATHER...FAB
Hazardous Weather Outlook National Weather Service Des Moines IA 259 PM CST Mon Mar 6 2017 IAZ004>007-015>017-023>026-033>037-044>049-057>061-070>074- 081>084-092>095-072100- Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo- Pocahontas-Humboldt-Wright-Franklin-Sac-Calhoun-Webster-Hamilton- Hardin-Crawford-Carroll-Greene-Boone-Story-Marshall-Audubon- Guthrie-Dallas-Polk-Jasper-Cass-Adair-Madison-Warren-Marion-Adams- Union-Clarke-Lucas-Taylor-Ringgold-Decatur-Wayne- 259 PM CST Mon Mar 6 2017 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight A Wind Advisory is in effect for the area. Please refer to the National Weather Service website at weather.gov/desmoines for further details. Thunderstorms are likely this afternoon and move very quickly northeast. There is a slight risk of severe storms with the main threat from damaging winds. Large hail is also possible along with an isolated tornado. The threat of severe weather will end later this evening. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Very strong winds are expected on Tuesday across much of the area with strongest winds in northern Iowa. This will also produce a very high to extreme fire danger across the area as well during the day on Tuesday. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon and into the evening. IAZ027-028-038-039-050-062-075-072100- Butler-Bremer-Grundy-Black Hawk-Tama-Poweshiek-Mahaska- 259 PM CST Mon Mar 6 2017 This Hazardous Weather Outlook is for portions of central Iowa. .DAY ONE...This afternoon and tonight Thunderstorms will become likely by early evening and move very quickly northeast. There is a slight risk of severe storms with the main threat from damaging winds. Large hail is also possible along with an isolated tornado. The threat of severe weather will end later this evening. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Strong winds are expected on Tuesday across much of the area with strongest winds in northern Iowa. This will also produce a very high to extreme fire danger across the area as well during the day on Tuesday. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed later this afternoon and into the evening. IAZ085-096-072100- Monroe-Appanoose- 259 PM CST Mon Mar 6 2017 This Hazardous Weather Outlook is for portions of southeast Iowa. .DAY ONE...This afternoon and tonight A Wind Advisory is in effect for the area. Please refer to the National Weather Service website at weather.gov/desmoines for further details. Thunderstorms will become likely by early evening and move very quickly northeast. There is an enhanced risk of severe storms with the main threat from damaging winds. Large hail is also possible along with tornados. The threat of severe weather will end late this evening. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Very strong winds are expected on Tuesday across much of the area with strongest winds in northern Iowa. This will also produce a very high to extreme fire danger across the area as well during the day on Tuesday. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed late this afternoon and into the evening. IAZ086-097-072100- Wapello-Davis- 259 PM CST Mon Mar 6 2017 This Hazardous Weather Outlook is for portions of southeast Iowa. .DAY ONE...This afternoon and tonight Thunderstorms will become likely by early evening and move very quickly northeast. There is an enhanced risk of severe storms with the main threat from damaging winds. Large hail is also possible along with tornados. The threat of severe weather will end later this evening. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Strong winds are expected on Tuesday across much of the area with strongest winds in northern Iowa. This will also produce a very high to extreme fire danger across the area as well during the day on Tuesday. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed late this afternoon and into the evening. REV
Special Weather Statement National Weather Service Des Moines IA 1111 AM CST Mon Mar 6 2017 IAZ033-034-044>046-057-058-070-071-081-082-092-093-062300- Sac-Calhoun-Crawford-Carroll-Greene-Audubon-Guthrie-Cass-Adair- Adams-Union-Taylor-Ringgold- Including the cities of Sac City, Lake View, Odebolt, Wall Lake, Schaller, Early, Rockwell City, Manson, Lake City, Pomeroy, Denison, Carroll, Jefferson, Audubon, Exira, Guthrie Center, Panora, Bayard, Casey, Atlantic, Greenfield, Stuart, Adair, Fontanelle, Corning, Creston, Bedford, Lenox, New Market, and Mount Ayr 1111 AM CST Mon Mar 6 2017 ...Elevated Fire Risk This Afternoon... Strong south southwest winds and lowering relative humidity this afternoon will combine for an elevated fire risk this afternoon. Between 1 and 5 pm relative humidity values will drop to near 30 to 35 percent. Grass fires that develop today are likely to spread quickly over the area during this time. Burning of any kind is highly discouraged today due to the conditions. In addition...Tuesday will be another day of dry conditions and strong northwest winds over much of the state. Additional statements may be issued later today regarding the elevated fire danger threat tomorrow. REV
The Des Moines radar (KDMX), 170 km away, was scanning. The volume nearest the first event began at 22:05 UTC.
43 thunderstorm wind, 27 hail, 13 tornado. Local standard time, as filed.
Picture submitted to broadcast media and shown on social media, relayed by COOP observer.
Trained spotter reported wind driven hail broke multiple window screens at the residence.
Spotter reported broken storm windows along with a few medium to large tree branches down.
Trained spotter reported 52 kt winds along with pea to dime sized hail.
Trained spotter reported golf ball sized hail between Fort Dodge and Barnum.
Trained spotter/Coop observer reported up to quarter sized hail.
Public reported pea to quarter sized hail for about 5 minutes. Delayed report.
Public reported between quarter and golf ball sized hail. Report via social media.
Report via social media.
Public reported quarter sized hail.
Public reported up to 2 inch sized hail. Report relayed by media on twitter.
Report via social media.
Public reported golf ball sized hail. Report relayed by KAAL via social media. Time and location estimated by radar. Delayed report.
Trained spotter reported pea to penny sized hail.
Trained spotter reported wind gusts to 60 mph along with nickel sized hail.
Local Fire Department reported nearly golf ball sized hail.
Trained spotter reported two inch branches blown over along with tine blown off metal buildings and doors blown off of a grain elevator.
The RWIS station at Rockwell City recorded a gust.
Trained spotter reported lots of quarter sized hail.
Trained spotter reported ongoing quarter sized hail.
Trained spotter reported nickel sized hail.
Public reported quarter to half dollar sized hail via social media.
Trained spotter reported dime to quarter sized hail covering the ground.
Public reported quarter sized hail via social media.
Weak tornado caught on video by storm chasers. Tornado stayed in rural areas of Webster County south of Harcourt with little damage.
Video evidence submitted by a firefighter showed a tornado touchdown approximately 3 miles west northwest of Dayton with dust and debris being lifted into the air. Tornado significantly damaged a hog confinement facility along with damaging power lines.
Public reported up to golf ball sized hail.
Mesonet station in Webster City recorded a 60 mph wind gust.
Trained spotter reported a semi blown on its side on Highway 20 near Webster City. Time estimated via radar.
Public reported that thunderstorm winds took out power in Webster City. Reported via social media.
KLMJ Radio in Hampton reported damage to a machine shed, greenhouse, and trees between Rowan and Latimer along Highway 3. Time estimated by radar.
Emergency manager reported power lines down in town.
Law enforcement reported wind gusts to 60 mph or more.
Public reported tree and farm out building damage, including roof sections missing. Time estimated by radar.
Trained spotter reported nickel sized hail along with estimated wind gusts to 60 mph.
Tornado began near the Des Moines River just west of Ledges State Park. This tornado tracked northeast for several miles producing mainly EF0 damage. The tornado likely had intermittent contact with the ground, especially near Jordon to the Boone/Story County line. The tornado continued into Story County.
Law enforcement relayed public report of up to quarter sized hail.
Creston AWOS recorded a strong wind gust.
Retired NWS Employee reported pea sized hail, small branches down, and wind gusts to 60 mph.
Trained spotter reported nickel to quarter sized hail.
Tornado continued from Boone County into Story County. The tornado produced tree and shed damage southwest of Gilbert before downing power lines just west of Gilbert. Additional tree and outbuilding damage occurred as the tornado raced northeast with an intermittent track.
NWS employee estimated 50-60 mph wind gusts at NWS office in Des Moines.
Ames ASOS recorded wind gust to 67 mph.
Public reported 50 to 60 mph wind gusts along with pea size hail.
Law enforcement reported power poles leaning due to wind about a half mile north of the Story-Hardin County line on S27. This is a delayed report and time estimated by radar.
Tornado developed south of Hubbard and moved quickly northeast. Tree and power line damage occurred along it's path with some outbuilding damage to the southeast of Hubbard.
Coop observer reported minor tree damage and damage to local street signs.
Trained spotter reported up to nickel sized hail.
Public reported up to penny sized hail, via social media.
Trained spotter estimated wind gusts to 60 mph along with dime sized hail.
Trained spotter reported nickel sized hail.
Law enforcement relayed public report that power out in New Providence due to very strong winds along with pea to nickel sized hail.
Law enforcement reported power lines and trees down. This is a delayed report and time estimated by radar.
Estimated 60 mph winds with pea size hail too. Report via social media.
Emergency manager reported wind gusts to 60 mph along with nickel sized hail. The city of Ackworth was also reported to have lost power.
Emergency manager reported up to quarter sized hail.
Emergency manager reported power poles down and a cattle building damaged near D35 and T19.
Trained spotter reported a downed power pole over Highway 92 blocking westbound traffic. Damage done by straight line winds and time estimated by radar.
Law enforcement reported two utility poles downed about a quarter miles east and south of E Ave. This is a delayed reported and time estimated by radar.
Law enforcement reported outbuildings damaged. This is a delayed report.
Law enforcement reported a barn moved off of its foundation and heavily damaged. This is a delayed report and time estimated by radar.
Tornado developed southwest of Milo and moved quickly northeast. It destroyed a small outbuilding shortly after developing. It then destroyed another garage tossing it several hundred yards before settling on the other side of the road in a neighbors yard. Additional tree damage occurred before encountering another residence where significant roof and window damage occurred. The tornado then continued in mainly rural areas southeast of Milo with only tree damage prior to lifting.
NWS storm survey confirmed a tornado touchdown approximately 5 miles west of Knoxville. An outbuilding was heavily damaged in this area and significant roof damage occurred to a residence. This is consistent with winds of 90 to 100 mph - or EF1 damage.
Lamoni ASOS recorded a 77 mph wind gust.
NWS storm survey confirmed another tornado touchdown approximately 4 miles northwest of Knoxville. Roof damage occurred to a few residences with large sections of shingles removed along with tree damage. This is consistent with winds of 85 to 95 mph - or EF1 damage.
Emergency manager reported structure damage in Marion County. Location and time radar estimated.
Marshalltown ASOS recorded strong wind gust.
Marshalltown ASOS recorded a 64 mph wind gust.
NWS storm survey found the last tornado in a series from the same storm in northeast Marion county. The tornado touchdown and moved quickly northeast producing mainly tree damage. However, one barn was shifted off its foundation with several other open air structures being destroyed altogether. Damage was rated high end EF0.
Waterloo ASOS recorded a 59 mph wind gust.
Public reported wind gusts to 60 mph.
Gust recorded at the Pella Iowa RWIS station.
Public reported nickel sized hail, via social media.
NWS storm survey confirmed a tornado touched down about six miles southwest of Seymour in Wayne County where several trees sustained major damage and several farmsteads were damaged. The tornado then tracked northeast through rural sections of Wayne County and produced sporadic tree damage. The tornado then moved into the south side of Seymour and produced significant damage to |several homes and structures with the partial collapse of walls and roof structures and widespread tree damage. A brick school building also sustained major damage to its roof and walls. After doing additional damage to residences to the northeast of the school, it exited Seymour and crossed into Appanoose County.
Trained spotter reported power out one mile west of Seymour along with very strong winds and heavy rainfall.
Tornado crossed into Appanoose county from Wayne county. After crossing into Appanoose county, the tornado damaged a residence along 110th Avenue with several|trees being topped and buildings damaged. The tornado continued across mainly rural areas of western Appanoose county before crossing IA Highway 2 where minor|damage occurred to a farmstead. The tornado appeared to dissipate shortly after crossing Highway 2.
Emergency manager reported power lines down, house damage, and a barn blown down.
Trained spotter reported wind gusts to 60 plus MPH and quarter sized hail.
Tornado developed just east of Cincinnati and moved rapidly to the northeast. The tornado damaged many trees along its path as well as a few different outbuildings with top wind speeds of 90mph - of EF1 damage.
NWS storm survey confirmed a tornado touchdown on the south side of Centerville just after 830 pm. The tornado produced significant damage to a manufacturing facility with a partial collapse of walls and roof structures. The tornado tracked very quickly northeast damaging an outbuilding and taking a large section of a roof off a residence along Highway 2. Damage was also found to several outbuildings at a farmstead south of Udell with a camper being tipped on its side. The worst damage occurred near Centerville where damage was consistent with winds of 115 to 125 mph - or EF2 damage. Damage to the east was not quite as intense generally EF0 or EF1 damage. It should be noted that the tornado may not have been continuous along the the entire 10 mile path...as the damage appeared to be more intermittent.
Ottumwa ASOS recorded 69 mph wind gusts.
Law enforcement reported several trees down throughout town along with a roof off of a house on S. Madison Ave and a metal shed destroyed on 50th Street. This is a delayed report and time estimated from radar.
Public reported a large pine tree uprooted.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2017Every state in 2017This day in weather historyThe tornado archive for Iowa, 2017Warnings in Iowa, March 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: 685998, 674623, 674625, 674628, 674624, 674627, 674629, 674630, 687637, 674635, 674638, 687638, 674640, 674641, 674642, 674643, 674645, 687642, 674644, 674646, 674647, 674648, 674649, 674650, 676728, 676729, 675028, 675029, 675044, 675045, 675046, 675047, 675048, 675050, 675049, 676730, 675052, 687644, 675051, 675053, and more.