Rains, along with thunderstorms and many downpours soaked Minnesota over a 48-hour period, beginning in the evening of Tuesday September 10th and ending in the evening of Thursday September 12th.
The rains were associated with a slow-moving, large, and rather intense low pressure system that formed in Colorado and made its way through the Northern Plains and Upper Midwest. This complex weather system generated three waves of heavy rain and thunderstorms.
The first wave of storms developed on Tuesday night in southern South Dakota and plowed eastward throughout the night. The storms were perhaps most famous for dropping short-lived but powerful tornadoes in the Sioux Falls, SD area just before midnight, producing the most damage in the city's history. In Minnesota, these storms rattled windows and produced 1-2 inches of rain over the southern third of the state, with an EF-1 tornado also confirmed near Winona just after 6 AM on Wednesday.
The second round of thunderstorms and heavy rain began late Wednesday evening in far southwestern Minnesota, with storms regenerating continuously for several hours near Pipestone, Avoca, and Slayton. The storms and rain did spread over much of the rest of Minnesota on Thursday morning, but by far the heaviest rains and highest totals were found in southwestern areas of the state, where observers and automated gages reported 4 to over 8 inches of rain from the overnight storms alone. Streams in the area surged to record flood levels in response. The 8-inch, 24-hour rainfall totals reported near Slayton and Avoca exceed the 200-year return thresholds for that area, meaning they have an annual probability of occurrence under a half of a percent. Away from these significant rainfall extremes, totals from this second round were generally 1.5 to 3 inches along and around the middle and upper Minnesota River, with totals tapering to an inch or less through the eastern Twin Cities.
The final round thunderstorms erupted on Thursday afternoon over southeastern Minnesota, as more strong thunderstorms trudged from Albert Lea to Rochester, Wabasha, and Winona. The highest rainfall totals were found near Austin, where 3-4 inches were common.
For the entire 48-hour event, rainfall approached 10 inches in the hardest-hit areas of southwestern Minnesota, exceeded three inches over large swaths of central and southern Minnesota, and were greater than one inch over the majority of the state.
Below are rainfall totals gathered by the National Weather Service Sioux Falls office, and severe storm reports gathered by the office in La Crosse. Please note that totals represent 2-day precipitation totals, and that many of the reports are from South Dakota. Although this storm produced some extreme 1-day precipitation totals, the extremes were spatially isolated and covered only small areas. As a result, this storm does not qualify as a "Mega-rain" event.
Public Information Statement National Weather Service Sioux Falls SD 1157 AM CDT Thu Sep 12 2019 ...TWO DAY PRECIPITATION REPORTS ENDING THURSDAY MORNING... Location Amount 6 NNE Coleman 11.00 in Avoca 10.92 in North Branch Pipestone Creek 10.80 in Pipestone Creek 10.65 in 6 E Sinia 10.00 in 1 W Mitchell 9.49 in Skunk Creek 9.24 in Edgerton 0.5 W 9.08 in Edgerton 0.2 WSW 8.86 in Chester 2n 8.81 in Pipestone Creek 8.41 in Emery 10.8 S 8.14 in Madison 5.0 SE 7.67 in Mitchell 6.2 S 7.61 in Mitchell 3.4 SSE 7.59 in Brookings 10 SE 7.20 in Redstone RAWS 7.12 in Pipestone Raws 7.10 in Mitchell Municipal Airport 7.09 in Willow Creek 7.02 in Parkston 6.5 WSW 6.78 in Montrose 2.4 E 6.78 in Skunk Creek 6.74 in Rock River 6.71 in Split Rock Creek 6.58 in Burke 2.4 NE 6.55 in Howard 5.3 W 6.53 in White Lake 6.49 in Mitchell 6.41 in Redwood River 6.39 in Redwood River 6.38 in 5 N Mt Vernon 6.35 in Aurora 0.3 NE 6.32 in Academy 2 NE 6.31 in 4 W Tripp 6.22 in Brookings 0.5 E 6.19 in Flandreau 6.15 in Mitchell 7.3 S 6.15 in Brookings 8.1 S 6.03 in Brookings 1.4 SW 5.96 in Oldham 0.9 E 5.77 in Stickney 3.8 SW 5.68 in Burke 4.2 SW 5.65 in Luverne 5.54 in Marshall 0.6 S 5.53 in Lake Andes 2.4 N 5.51 in Dimock 10.2 W 5.32 in Sioux Falls Western Avenue 5.21 in Gregory 8.7 N 5.17 in Oldham 1.9 ENE 5.13 in Wall Lake Precipitation 5.13 in James River 5.11 in Brookings 0.2 SSW 4.95 in Aurora 7.5 N 4.94 in Eros Data Center 4.91 in Brookings 2 NE 4.74 in Lakefield 7.8 N 4.68 in White 1.7 SSW 4.59 in Hurley 0.2 S 4.59 in Howard 10.3 NNE 4.54 in Brookings Municipal Airport 4.53 in Garretson 4.2 SSE 4.35 in Marshall Municipal Airport 4.17 in Sioux Falls NWS 4.08 in Astoria 2.2 SSE 3.93 in Sioux Falls 3.3 E 3.69 in Sioux Falls 3.9 SW 3.66 in E.fork Vermillion Rvr 3.66 in Sioux Falls Airport 3.64 in Perry Creek 3.62 in White 0.4 WNW 3.62 in Marion 4.8 NNW 3.59 in Ocheyedan River 3.56 in Sioux Falls 4.5 SSW 3.53 in Tea 1.1 NNW 3.53 in Kimball 3.9 ENE 3.49 in Worthington 2 NNE 3.48 in Rock River 3.44 in Renner 4.1 NW 3.42 in Brookings 5.3 N 3.31 in Sioux Falls 3ese 3.27 in Kingsley 0.5 S 3.27 in Sioux Falls 5.0 SE ARPT 3.27 in Bruce 5.3 W 3.20 in Millnerville 3.19 in Lakefield 2 NE 3.11 in Sioux Falls 4.0 SE 3.10 in L. Sioux River 2.95 in Sioux Falls Harmondon Park 2.89 in W Fork Ditch 2.86 in Sioux City Perry Creek 2.84 in Arthur 3.7 SSW 2.80 in Rock River 2.80 in Worthington Airport 2.79 in Pukwana 1.9 S 2.75 in Spencer Municipal Airport 2.72 in Lake Park 0.2 N 2.69 in Jefferson 2.1 WNW 2.65 in Spirit Lake 2.59 in Sioux Gateway Airport 2.56 in Sioux Falls Oak View Library 2.56 in Bruce 0.2 SSW 2.53 in Cleghorn 4.4 N 2.38 in Lake Park 3.2 SSE 2.37 in Sioux Center 2.6 N 2.36 in De Smet 0.2 SSE 2.36 in Sibley 2.33 in Huron 6.8 NNE 2.25 in Floyd River 2.19 in Floyd River 2.16 in Cherokee 2.16 in Hitchcock 7.5 WSW 2.07 in Huron Regional Airport 2.05 in Emerson 1.95 in Forestburg 0.1 NE 1.95 in Chamberlain 0.3 W 1.93 in North Cliff-Big Sioux R 1.93 in Chamberlain 7.5 NNE 1.89 in Little Sioux River 1.76 in Vermillion 1.4 SE 1.55 in Jackson Airport 1.50 in Alta 0.3 SE 1.48 in Cherokee Municipal Airport 1.46 in Windom Municipal Airport 1.34 in Yankton 2 E 1.21 in Gayville 1.8 SSW 1.07 in Des Moines River 0.95 in Observations are collected from a variety of sources with varying equipment and exposures. We thank all volunteer weather observers for their dedication. Not all data listed are considered official. PRELIMINARY LOCAL STORM REPORT...SUMMARY NATIONAL WEATHER SERVICE LA CROSSE WI 714 PM CDT THU SEP 12 2019 ..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON... ..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.... ..REMARKS.. 0309 PM FLOOD AUSTIN 43.67N 92.97W 09/12/2019 MOWER MN LAW ENFORCEMENT EXTENSIVE STREET FLOODING IN TOWN WITH STRANDED MOTORISTS AND WATER ON PARTS OF I-90. 0310 PM HEAVY RAIN 2 NW LYLE 43.53N 92.97W 09/12/2019 M2.50 INCH MOWER MN TRAINED SPOTTER SINCE 130 PM. 0327 PM FLOOD AUSTIN 43.67N 92.97W 09/12/2019 MOWER MN LAW ENFORCEMENT INTERSTATE 90 BETWEEN HWY 218 AND HWY 56 CLOSED DUE TO HIGH WATER. 0346 PM TSTM WND GST 3 SW CHESTER 43.46N 92.41W 09/12/2019 M54 MPH HOWARD IA STORM CHASER VIA SPOTTERNETWORK.ORG. 0410 PM TSTM WND GST 4 S GREENLEAFTON 43.52N 92.22W 09/12/2019 M70 MPH FILLMORE MN TRAINED SPOTTER 0437 PM LIGHTNING ROLLINGSTONE 44.10N 91.82W 09/12/2019 WINONA MN EMERGENCY MNGR HOUSE FIRE REPORTED BY LIGHTNING. 0454 PM TORNADO 3 SSE OSSIAN 43.11N 91.74W 09/12/2019 WINNESHIEK IA EMERGENCY MNGR POSSIBLE TORNADO DAMAGE ABOUT 2.5 MILES SOUTH SOUTHEAST OF OSSIAN. 0454 PM HEAVY RAIN LIME SPRINGS 43.45N 92.28W 09/12/2019 M2.40 INCH HOWARD IA BROADCAST MEDIA FELL IN 45 MINUTES. RELAYED VIA MEDIA. 0455 PM TORNADO 2 SW OSSIAN 43.13N 91.79W 09/12/2019 WINNESHIEK IA FIRE DEPT/RESCUE JUST SPOTTED ALONG HWY W14. 0500 PM FLOOD 3 ENE SARATOGA 43.39N 92.36W 09/12/2019 HOWARD IA PUBLIC GRAVEL ROADS WASHED OUT AND WATER OVER GRAVEL ROADS ON KENT AVENUE EAST OF SARATOGA. 0509 PM TSTM WND DMG 3 SW ALTA VISTA 43.16N 92.46W 09/12/2019 CHICKASAW IA TRAINED SPOTTER TRAINED SPOTTER REPORTED TOPS OF TREES BLOWN DOWN ON ROADWAY SEVEN MILES EAST OF COLWELL. 0520 PM HEAVY RAIN AUSTIN 43.67N 92.97W 09/12/2019 M3.16 INCH MOWER MN PUBLIC RAINFALL SINCE 7AM THURSDAY. 0534 PM HEAVY RAIN ST. ANSGAR 43.38N 92.92W 09/12/2019 M3.97 INCH MITCHELL IA CO-OP OBSERVER 0544 PM HEAVY RAIN 8 W CHATFIELD 43.84N 92.35W 09/12/2019 M3.10 INCH FILLMORE MN AMATEUR RADIO 0551 PM FLOOD ROSE CREEK 43.60N 92.83W 09/12/2019 MOWER MN BROADCAST MEDIA WATER OVER ROAD IN VARIOUS SPOTS. 0555 PM FLOOD LA CROSSE 43.81N 91.25W 09/12/2019 LA CROSSE WI LAW ENFORCEMENT STREET FLOODING REPORTED AROUND TOWN. 0604 PM TSTM WND GST CLAYTON CENTER 42.88N 91.32W 09/12/2019 E60 MPH CLAYTON IA 911 CALL CENTER 0619 PM HEAVY RAIN 8 ENE DECORAH 43.34N 91.64W 09/12/2019 M2.42 INCH WINNESHIEK IA PUBLIC FELL WITHIN ONE HOUR. FIELD AND DITCH FLOODING. 0644 PM HEAVY RAIN 1 SE PRAIRIE DU CHIEN 43.03N 91.13W 09/12/2019 M1.85 INCH CRAWFORD WI TRAINED SPOTTER ONE HOUR RAINFALL TOTAL. 0653 PM FLASH FLOOD WOODMAN 43.09N 90.80W 09/12/2019 GRANT WI EMERGENCY MNGR WASHOUTS AND MUDSLIDES REPORTED. 0653 PM FLASH FLOOD BLOOMINGTON 42.89N 90.93W 09/12/2019 GRANT WI EMERGENCY MNGR WATER OVER ROADS IN BLOOMINGTON AREA.
Modified September 13, 2019