A front over the Northwest to the Great Basin brought rain and higher-elevation snow to parts of the region, as well as rain and extreme weather to most of the Plains and Lower Mississippi Valley as the front advanced eastward.
An additional front from southern Plains to the Great Lakes brought severe weather and thunderstorms from Texas to New York. Meanwhile, a sub-tropical upper-level high over Mexico brought record- to near-record warmth to portions of Texas. Temperatures were above normal across the eastern contiguous United States, by as much as 10-plus degrees Fahrenheit above average from parts of the eastern Great Lakes to the Northeast and in parts of Texas.
Precipitation was below normal across much of the southern contiguous U.S. and the Northeast, as well as portions of the Northwest and parts along the East Coast. The most widespread improvements were made to portions of the Midwest and in eastern parts of the High Plains and South. Above-normal precipitation fell in Montana.
Dry conditions continued across the western portions of the southern region, southern High Plains and Southeast, with degradations occurring in parts of the western Plains. Drought and abnormal dryness also expanded or intensified in portions of the northern Rockies.
The U.S. Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the U.S. Department of Agriculture and the National Oceanic Atmospheric Administration. (Map courtesy of NDMC.)
South
Dry conditions continued across the western portions of the South this week, while heavy precipitation fell across eastern portions of the region. Most of Arkansas as well as eastern parts of Oklahoma and Texas received between 1 to 6 inches of rainfall (200% to 800% above normal), resulting in the improvement of moderate drought (and abnormal dryness in Arkansas.
Conversely, conditions continued to deteriorate in parts of eastern Oklahoma and Texas, where precipitation totals were 1 to 4 inches below normal this month. Severe drought and moderate drought were expanded in parts of eastern Oklahoma, while moderate drought was introduced in southern Texas. Abnormal dryness was also expanded into parts of northern and southern Texas.
Temperatures were 2 to 8 degrees above normal across much of the region this week, while parts of southern Texas observed temperatures between 8 to 10 degrees above normal. The expansion and intensification of drought categories were based on short-term SPI/SPEI, reservoir levels, streamflow and soil moisture data.
Midwest
Average temperatures were well above normal across much of the Midwest, while below-normal temperatures were observed in western portions of the region. Northern portions of Minnesota observed temperatures up to 6 degrees below normal this past week.
Much of the Midwest also observed above-normal precipitation this week, especially along the western and southern portions of the region where the heaviest amounts totaled between 2 to 8 inches of rainfall and ranged between 1 to 8 inches (300% to 600%) above normal.
Above-normal precipitation helped to alleviate longer-term precipitation deficits and improved soil moisture and streamflow impacts, resulting in a 1-category improvement across southern Minnesota, eastern Iowa and southern Missouri. Improvements were also made to moderate drought and abnormal dryness in northern Minnesota.
High Plains
Precipitation fell across much of the region this week, which was enough to prevent further degradation but not enough to warrant large improvements. The heaviest rainfall amounts fell across much of North Dakota and along eastern portions of the region, where rainfall totals were up to 600% of normal and ranged between 1 to 4 inches this week.
Severe drought was improved in south-central Kansas, while improvements to moderate drought and abnormal dryness were made in northern Kansas and southeast Nebraska. Abnormal dryness was also removed from northern Wyoming and northeast North Dakota due to heavy precipitation and improvement shown in soil moisture and short-term SPI/SPEI indicators.
Conversely, dry conditions persisted in eastern portions of the High Plains this week. Deteriorating conditions shown in short-term SPI/SPEI, streamflow, soil moisture and snow water equivalent data justified degradations in Colorado and eastern portions of Nebraska and Kansas.
Extreme drought and severe drought were expanded in eastern Kansas, while moderate drought was introduced into southeast Wyoming where precipitation amounts were 50% of normal over the past month. Abnormal dryness was expanded in parts of Colorado, eastern Wyoming and western Nebraska.
West
Much of the West remained as status quo this week, while temperatures were 2 to 10 degrees below normal across most of the region. Precipitation fell across northern portions of the West, with the heaviest amounts falling over parts of western Washington and Montana. Above-normal precipitation (up to 3 inches), along with cooler temperatures (up to 10 degrees below normal), resulted in improvements to extreme drought, severe drought, moderate drought and abnormal dryness across parts of Montana.
Parts of southwest Montana missed out on some of the beneficial rains resulting in the expansion of moderate drought in the area.
Looking ahead
During the May 28 to June 1 period, moisture convergence along a frontal boundary and east of a dryline across Texas and Oklahoma will likely generate scattered to numerous showers and thunderstorms, with the potential for episodes of locally heavy rainfall early to mid-week.
The threat of heavy rainfall will be highest in Texas Tuesday into Wednesday as an upper level shortwave moves over the southern Plains, where the potential exists for storms with rainfall rates approaching 2 inches per hour. The coverage of showers and storms will likely expand north across the central and northern Plains later in the week as an organized frontal system moves into the central U.S. from the Rockies.
Locally heavy rainfall will be possible across portions of the Rockies going into late Friday and early Saturday as the cold front intercepts an increasingly humid airmass. In terms of temperatures, the Gulf Coast region will continue to remain hot and humid on Tuesday before some limited relief arrives by midweek as a cold front drops southward.
However, the heat and humidity will likely continue across Deep South Texas and South Florida with highs running up to 10 degrees above average, and heat indices in the 100- to 110-degree range, especially for southern Texas. Some triple digit heat is also likely for the lower elevations of the Desert Southwest, but very low humidity here will help keep heat indices in check.
The Climate Prediction Center’s six- to10-day outlook (valid June 2 to 6,) favors above-normal precipitation along much of the West Coast, from the southern Plains to the East Coast, and across much of Alaska, with below-normal precipitation across most of the interior West. Increased probabilities for above-normal temperatures are forecast for much of the contiguous U.S.
Rocky Bilotta is with the National Oceanic Atmospheric Administration and National Centers for Environmental Information.
