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Accumulated Precipitation (in) Average Temperature: Departure from Mean Date of first 32°F Freeze since 8/1/17 U.S. Drought Monitor: Midwest  

Midwest Weekly Highlights - August 22-31, 2017

Dry for Many, Wet in Western Iowa, Missouri

Dry weather was common for many areas across the Midwest during the last week of August (Figure 1).  Areas in Lower Michigan, Ohio, southern Missouri and southern Illinois had less than a half-inch of rain for the period.  Eastern Iowa, southern Wisconsin and northern Illinois had less than an inch.  In many cases, this was less than half the normal amount (Figure 2).  Wetter weather occurred along the western edges of the region in Iowa, Missouri and Minnesota.  Areas in western Iowa and northern Missouri had more than twice the normal amount.  A persistent thunderstorm on August 29 also dropped 2-4 inches of rain in the Fort Wayne, IN area (Figure 3, Allen County).  This prompted Flash Flood warnings as the rainfall fell in just a few hours.  Most of the thunderstorms during the week were sub-severe in nature, as only a few storm reports were reported (Figure 4).

Cool Temperatures Return

Below-normal temperatures returned to the Midwest in the last week of August (Figure 5).  Only a few areas in extreme northwestern Minnesota had near-normal temperatures, while the rest of the region was multiple degrees below normal.  Missouri and the western U.P. of Michigan were the coolest areas at 4-7°F below normal.  Most of Illinois, Indiana and Lower Michigan were 3-5°F below normal.  Several stations dipped to 32°F or below for the first freeze of the fall season in the arrowhead of Minnesota and western U.P. of Michigan on the morning of August 25 (Figure 6).  This was close to the climatological earliest dates for a first freeze in these areas (Figure 7).

Drought Decreases Slightly in Iowa

Another week of wet weather aided in the reduction of drought in western Iowa in the August 29 U.S. Drought Monitor (Figure 8).  Four to six inches of rain fell across western Iowa during the second half of August (Figure 9).  Western Iowa was the only area of improvement, however.  Moderate to severe drought persisted across south-central Iowa, while moderate drought remained in east-central Missouri and central Illinois.  More than three million people were still estimated to be living in drought affected areas.