A slow-moving cold front resulted in thunderstorms with heavy rainfall (locally more than 3 inches) across the central to southern Great Plains, lower Mississippi Valley, and the Ozarks Region from May 31 to June 2. As this front progressed eastward, locally heavy rain also fell across the Ohio Valley and Northeast.
South
Heavy rainfall (1.5 to 3 inches, locally more) resulted in a 1-category improvement to west-central Oklahoma and northwestern Texas, setting up a tight west to east gradient in Dx categories. In areas such as Custer County in western Oklahoma, that locally received as much as 8 inches of rainfall during the past week, a 2-category improvement was justified. This heavy rainfall extended southward into southeastern New Mexico and western Texas where parts of the Permian Basin, Davis Mountains, and Big Bend received more than 2 inches at the beginning of June.
Farther to the east across parts of central and eastern Texas, along with northwestern Louisiana, increasing short-term precipitation deficits (2 to 4 inches), above-normal temperatures, and higher evapotranspiration rates resulted in a 1-category degradation. This expansion of abnormal dryness (D0) was supported by 30 to 60-day SPEI and these areas stand out on the EDDI product for flash drought. Eastern Texas and northern Louisiana will have to be closely monitored in subsequent weeks as short-term drought could rapidly develop. Locally heavy rain (more than 1 inch) this past week resulted in a slight decrease in D0 for northeastern Louisiana. On June 6, heavy rainfall extended south of the Ohio River which led to a general decrease in the small areas of D0 in Tennessee.
Midwest
Recent heavy rainfall on June 6 resulted in a decrease in abnormal dryness (D0) across Indiana, Kentucky, and southeastern Illinois. However, east-central Illinois missed out on this rainfall and 30 to 60-day SPIs along with soil moisture from NASA SPoRT support the introduction of D0 to that part of Illinois. 30-day deficits of more than 2 inches exist across parts of central to southern Illinois and southeastern Iowa. The lack of anomalous warmth through the beginning of June has limited evapotranspiration rates and significant drying of topsoil.
High Plains
Heavy rainfall (1.5 to 3 inches, locally more) this past week resulted in a 1-category improvement to southeastern and central Kansas. More than 1.5 inches of rainfall this past week, along with soil moisture and long-term SPIs, supported a change from exceptional (D4) to extreme (D3) drought in parts of southwestern Kansas and adjacent southeastern Colorado. Widespread beneficial rainfall, exceeding 1 inch, this past week prompted a 1-class improvement to much of eastern Colorado. Swaths of heavy rainfall (more than 1 inch) also led to improvements of various Dx categories across parts of Nebraska and South Dakota. Much above-normal precipitation during the past 30 to 90 days and soil moisture percentiles supported the elimination of moderate drought (D1) across much of west-central Wyoming.
West
The wet late spring continues to support improving conditions from the Pacific Northwest eastward to the Northern Rockies. Based on multiple indicators including springtime precipitation, soil moisture, and streamflow, a broad 1-class improvement was made to eastern Washington with improving conditions also supported for parts of Oregon. The recent precipitation was enough to shift the long-term SPEIs out of exceptional (D4) drought in much of Klamath and Lake Counties of Oregon. In western Idaho, severe drought (D2) was improved to moderate drought (D1) based in part on the hydrologic response in the Weiser Basin. Southwestern Montana had a 1-class improvement, following recent wetness, soil moisture recharge, and 60-day SPI. Precipitation amounts of 1 to 3 inches along with below-average temperatures resulted in a 1-category improvement to parts of north-central Montana.
Despite the recent cool pattern, 90 to 180-day SPIs supported 1-category degradation to parts of northern Montana. Impacts in this worsening drought area include required supplemental feeding, very dry soils, and dry stock ponds. Based on 90-day SPI and hydrology considerations in the Sevier River basin, extreme (D3) to exceptional (D4) drought was expanded across parts of Utah. Widespread severe to exceptional drought persists throughout much of the Southwest, Great Basin, and California. Hydropower production concerns at reservoirs in California and Nevada continue due to low water levels.
