Northwest Iowa — Saturday, August 5th was a rainy and stormy day, and by nightfall, the area had seen tornados and torrential rainfall.
A Flash Flood Watch started off the reports from the National Weather Service at 12:15 Saturday afternoon. It was issued for north central Cherokee, northeastern Lyon, central O`Brien, and western Osceola counties. It said doppler radar had been indicating thunderstorms producing heavy rain and rain rates could reach two to four inches per hour.
The next report was a mid-storm rain report that three and a half inches of rain had fallen in Sanborn already, as of 2:00 p.m.
Next, was a weather report of a different type — a tornado warning for central Sioux County and specifically the city of Sioux Center at 2:09 p.m. It said a severe thunderstorm capable of producing a tornado was located over Maurice, moving north at 15 miles per hour. That warning was to have gone until 2:45, but at 2:39, the weather service extended it until 3:15. People took shelter in the Sioux Center area, with shoppers at the local Walmart sheltered in place in the rear restrooms of the building until the warning was over.
At 3:00, the Storm Prediction Center issued a tornado watch for portions of western Iowa, southwest Minnesota, northeast Nebraska, and southeast South Dakota. That would be the last we heard of tornadoes in the four northwesternmost counties of Iowa, as after that, the main issue would be all the heavy rain and the aftermath that would cause.
A flash flood warning was issued for south central Lyon County and central Sioux County at 3:18 p.m. It warned of flash flooding in Sioux Center, Orange City, Rock Valley, and Maurice.
At 3:40 p.m., Highway 75 was reported blocked between B46 and B30 at the south and north ends of Sioux Center due to standing water.
At 3:49 p.m., the Sioux County Sheriff’s Office reported some streets in Rock Valley were impassable due to flash flooding. At that very same time, they also said no travel was advised in Sioux Center due to the flooding, and reported vehicles stuck in flooded streets.
The next report received by the weather service was a mid-storm report that 4.59 inches of rain had fallen so far in Hull.
At 4:41, a flash flood warning was issued for southeastern Lyon and northeastern Sioux counties due to heavy rain having fallen and heavy rain expected to continue at two to four inches per hour. It mentioned that Hull, Boyden, and Doon could be affected.
The weather service took a report at 5:15 p.m. of street flooding in Boyden after the town had received approximately seven inches of rain up until that point.
Then, at 5:20, came another flash flood warning — this one for eastern Lyon, all of O’Brien, western Osceola and northeastern Sioux counties. It mentioned flash flooding would be experienced in Sheldon, Sibley, Hartley, Sanborn, Primghar, Sutherland, Little Rock, Ashton, Melvin, Matlock and Calumet.
At 5:38, they took a report that Highway 18 was closed in both directions near Boyden between K64 and L14, due to standing water on the roadway.
At 5:49, the weather service extended the flash flood warning for south central Lyon and central Sioux counties until 7:30, and again mentioned flash flooding was occurring in Sioux Center, Orange City, Rock Valley, and Maurice. An eyewitness report noted many streams in Sioux Center in flood condition, with West Side Park completely underwater.
The weather service sent out a severe thunderstorm warning at 6:39 p.m. for northwestern Cherokee and southwestern O’Brien counties for a storm near Granville moving east at 20 miles per hour. They mentioned the main threat of this system was 60-mile-per-hour wind gusts and said it would be near Paullina and Larrabee.
The final event was the issuance of a flood warning for Sioux County, issued at 7:27 p.m., which was to go until 10:30 p.m. for streams continuing to rise due to excess runoff from earlier rainfall. It mentioned between four and nine inches of rain had already fallen, with one to two more inches predicted.
Some 24-hour rain reports received by the National Weather Service:
Sioux Center 10.0″
1S Sioux Center 9.02″
2S Sioux Center 8.88″
1W Boyden 8.38″
2E Hull 7.87″
5W Sioux Center 6.17″
Hull 5.62″
Paullina 3.28″
Sanborn 3.26″
Primghar 3.54″
Sheldon 2.22″
Other reports:
Ashton 5.25″
Ashton 5.05″
George 4.5″
Matlock 3.11″
East Sheldon 3.1″
Rock Rapids 1.07″, plus another inch by Sunday morning.
Feel free to text rain amounts and storm damage reports to 712-324-2597.
