August 2022 Hydrologic and Precipitation Summary

August 2022 Hydrologic & Precipitation Summary

Summary:

During August 2022, it was primarily wetter-than-normal across The Upper Mississippi River Valley. Rain totals ranged from 3.33” at La Crescent Dam (COOP) to 9.87” at Medford, WI (COOP). The greatest 1-day rainfall was 4.02" near Black River Falls, WI (CoCoRaHS). This rain fell from 7 AM on August 27 to 7 AM on August 28.

Rainfall anomalies ranged from 2” drier-than-normal to 4” wetter-than-normal across the Upper Mississippi River Valley. Medford, WI had their 2nd wettest August (9.87”). Only 1941 was wetter with 10.74". Both Caledonia, MN (9.38” – their wettest August was 18.96" in 2007) and Genoa Dam 8, WI (8.26” – their wettest August was 19.80" in 2007) had their 6th wettest August. Finally, New Hampton, IA had their 10th wettest August (8.31” – their wettest August was 18.60" in 2021). No areas were among their 10 driest.

Flood Conditions:

During the evening of August 27, from 2 to just over 3 inches of rain fell across southeast Winneshiek County and southwest Allamakee counties in northeast Iowa. This prompted a Flash Flood Warning. The highest rainfall total was 3.15” near Waukon, IA (CoCoRaHS). This was the only Flash Flood Warning for the month. The August long-term average (1986-2022) is two.

River Conditions:

During August, there was no river flooding in the La Crosse Hydrologic Service Area (HSA).

The Mississippi River at La Crosse, WI had an average 7 AM stage of 5.28 feet during the month. This was 0.07 feet below the 1937-2022 long-term average of 5.35 feet. The highest stage was 5.88 feet on August 31 and the lowest stage was 4.81 feet on August 2. This site has not been at or above flood stage (12 feet) since April 13, 2020. This ongoing stretch of 871 days is the 11th longest without reaching the flood stage. It is the longest since a 1,108-day stretch from April 22, 2011, to May 3, 2014 (the 9th longest stretch). The longest stretch was a 3,986-day stretch from May 12, 1954, to April 9, 1965.

Drought:

At the beginning of August 2022, abnormally dry (D0) conditions covered 2.3% of the La Crosse Hydrologic Service Area. Moderate drought (D1) developed in Wabasha County in southeast Minnesota and in Buffalo, Jackson, and Trempealeau counties in west-central and central Wisconsin by mid-month. This was also when the maximum moderate drought extent occurred at 5.2% of the La Crosse HSA. By the end of the month, only 0.4% of the moderate drought remained (northwest Buffalo County) and 4.8% of the HSA was abnormally dry.

Precipitation