Heavy to excessive rainfall brought relief to parts of the Midwest and High Plains last week, but unusually hot weather and low humidity continue to worsen conditions across large sections of both regions, according to the latest U.S. Drought Monitor. The U.S. Drought Monitor is produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the U.S. Department of Agriculture, the National Oceanic and Atmospheric Administration and NASA.
The contrasting conditions created a patchwork of improvements and deterioration across the central United States, with some areas receiving enough rain to end drought designations entirely while others slipped deeper into severe conditions.
Midwest sees widespread improvements
Moderate to heavy rains fell across much of the Midwest, with most locations receiving at least 0.5 inch of precipitation. Several areas experienced heavy to excessive rainfall exceeding 2 inches, including northwestern and southern Minnesota, southern and eastern Iowa, southern Wisconsin, much of northern Illinois, central Indiana and parts of western Ohio.
The most significant rainfall occurred in a band stretching from Kandiyohi and Chippewa counties in interior southern Minnesota southeastward through portions of Renville, McLeod, Sibley and Le Sueur counties, where widespread amounts of 5 to 7 inches were recorded.
These rains removed all dryness and drought from some areas and brought broad improvements to northwestern Minnesota, southeastern Wisconsin, northern Illinois, parts of central and northwestern Indiana, and southeastern Kentucky.
However, heavier rains missed some locations, allowing drought to intensify in east-central and west-central Michigan, northern Wisconsin, part of central and northwestern Iowa, and the northern and southern tiers of Missouri. These areas recorded just 10% to 50% of normal rain for the past 30 days, while 90-day totals near or under half of normal were observed through northern Wisconsin, parts of central and northern Minnesota, and scattered patches across Lower Michigan, Missouri, Illinois and parts of northern Indiana and Ohio.
Rainfall deficits of 4 to 8 inches over 90 days now cover much of northern Wisconsin and adjacent Michigan, along with other scattered areas across the region.
High Plains face extreme conditions
Conditions varied dramatically across the High Plains. Heavy rains of 2 to 5 inches, with isolated higher amounts, fell on northeastern South Dakota, much of northern and eastern Nebraska, and northeastern Kansas. Eastern South Dakota, central through eastern Nebraska, southeastern Colorado and western Wyoming saw significant improvements.
But the western portions of the region faced deteriorating conditions driven by unusual heat and low humidity. In North Dakota, central and western South Dakota, and western Nebraska, temperatures averaged 4 to 8 degrees Fahrenheit above normal for the past 30 days. Some spots in the western Dakotas and adjacent parts of Wyoming and Nebraska reported 30-day average temperatures 8 to 10 degrees above normal, including several days with highs exceeding 100 degrees.
Making matters worse, relative humidity has been unusually low. Many areas across eastern Wyoming, western South Dakota and adjacent Nebraska reported four-week relative humidity averaging among the driest 10% of historic observations for the time period. A few isolated spots were as dry as the lower 2% of historical observations.
Most of North Dakota, the western half of South Dakota, and parts of northeastern Wyoming, western Nebraska and northeastern Colorado saw conditions deteriorate. Southern Kansas adjacent to Oklahoma also worsened.
A new patch of exceptional drought, the worst classification, was introduced in northwestern Nebraska and another in part of the Denver metro area. Existing areas of exceptional drought remained in the Nebraska Panhandle, east-central Colorado, south-central and interior western Colorado. Most of Wyoming and Colorado remain in extreme drought, as do western reaches of Nebraska and South Dakota.
In contrast, dryness has been entirely removed from large parts of southeastern Nebraska, eastern Kansas and the east-central Dakotas.
Looking ahead
Forecasters expect little heavy rainfall across the continental United States through Aug. 10, with most areas from the central Great Plains westward anticipating little or no precipitation. Temperatures are expected to stay near to above normal, especially over the Great Plains westward, where areas outside the Pacific Northwest and immediate West Coast may see temperatures 5 to 11 degrees above normal.
