Rain and Flooding, September 10-12, 2019

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 Harmodon 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