Billion-dollar rain? Storms soaked Minnesota's driest cropland Tuesday night

You’ve probably heard the phrase million-dollar rain. That might be conservative for the value of the rainfall zone across southern Minnesota Tuesday night.

The swath of heavy rainfall from the derecho storm that blew through southern Minnesota Tuesday evening fell on some of the driest farm fields in our state. Some of the rainfall was too heavy in places —Albert Lea picked up a flash flooding 5 inches in just a couple of hours.

But a big swath of southern Minnesota got beneficial rains in the 1 to 2-inch range. And a lot of thirsty corn and bean field acreage drank up the soaking at a critical time for farmers.

Trending dry

Most of southern Minnesota has been trending dry this summer. Last week’s U.S. Drought Monitor shows abnormally dry soil conditions from the Twin Cities area southward to the Iowa border. And a sliver of moderate drought had emerged along Interstate 90 near the Iowa border.

Now, look at the spatial distribution of Tuesday’s rainfall zone. You can see the swath of heavy rainfall that covered the southern rows of counties in Minnesota. Basically, most areas from Mankato southward into Iowa got significant rainfall last night. A well-timed swath of 1 to 3 inches fell in that zone.

Here are some select rainfall totals from Tuesday evening across southern Minnesota. The 5 inches that fell in Albert Lea is too much (flooding) rain.

But many locations picked up a more beneficial 1 to 3 inches last night. Keep in mind that summer convective rainfall totals are often highly variable over short distances.

• Albert Lea, 5.1 inches

• Austin, 2.78 inches

• Blue Earth, 2.1 inches

• Comfrey, 2.3 inches

• Austin, 2.17 inches

• Worthington, 1.75 inches

• St. James, 1.73 inches

• Rochester, 1.05 inches

Still dry farther north

Areas north of the heavy rain zone missed out on the most significant rainfall. For example, the U.S. Highway 212 corridor from western Minnesota eastward into the Twin Cities saw less rainfall. It’s still dry in that zone and more rainfall is needed for crops, lawns, lakes, and rivers.

Less wind

Southern Minnesota farmers are lucky that the highest winds blew across South Dakota Tuesday. Check out the corn blow-down in some areas of South Dakota.

Rainfall coverage looks spotty through Saturday. A wider chance for thunderstorms looks possible Saturday night or Sunday.

Stay tuned.