Welcome rains fell in parts of the Plains
This past week, widespread precipitation impacted much of the United States, with heavier amounts (exceeding 1 inch) observed from the northern Rockies eastward to the East Coast.
Specifically, much of the High Plains reported 2 to 10 inches of rain, while similar totals (2 to 8 inches) were seen across parts of the South and Midwest. This above-normal precipitation supported drought improvements across large portions of the High Plains, parts of the Midwest, and smaller pockets of the West and South. Conversely, below-normal weekly precipitation occurred in parts of the western U.S., the Midwest, and Southeast, leading to the expansion or intensification of drought and abnormal dryness in western High Plains, eastern West, and parts of the Midwest and Southeast.
Temperatures were above normal across much of the U.S. The southern U.S., from Texas to Mississippi, saw temperatures up to 10 degrees Fahrenheit above normal. In contrast, below-normal temperatures, with departures up to 10 degrees below normal, were observed across much of the West and western High Plains, with the largest departures noted in the Dakotas and interior West.
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
Warmer temperatures dominated the South, with departures ranging up to 10 degrees above normal. However, parts of Texas and Oklahoma observed temperatures near or below normal.
Precipitation varied across the region, with heavier amounts (2 to 8 inches) falling across much of Arkansas, eastern Oklahoma, and small parts of Texas. Unfortunately, not many improvements were made due to rain falling over areas already free of drought and abnormal dryness, but conditions prevent existing drought from expanding or intensifying. Arkansas is free of drought and abnormal dryness.
Midwest
Above-normal temperatures, with departures ranging between 1 to 8 degrees above normal, were observed across most of the Midwest. The largest temperature departures were observed in pockets in northeastern Minnesota. In contrast, temperatures were below normal across much of Minnesota and in parts of Iowa. Precipitation was reported across most of the region, with the greatest amounts (3 to 6 inches) falling in parts of Minnesota, Iowa and Missouri.
This above-normal precipitation led to moderate drought improvements in parts of Minnesota and Missouri with abnormal dryness improvements across western portions of the region.
However, precipitation was below normal in northern parts of Minnesota with rainfall totals at 50% or less. Growing precipitation deficits and degrading conditions (indicated by short-term indicators, streamflow, and soil moisture) resulted in abnormal dryness expanded in northern Minnesota and eastern Indiana.
High Plains
Temperatures varied across the High Plains, with departures ranging up to 8 degrees above normal, while cooler-than-normal temperatures were observed along the western and northern portions of the region.
Heavy precipitation fell across much of the region, with areas from North Dakota to northern Nebraska reporting weekly precipitation totals between 400% to 600% above normal. These beneficial rains (2 to 8 inches above normal) justified widespread moderate to extreme drought improvements in the Dakotas and Nebraska.
Additionally, improvements of moderate to severe drought and abnormal dryness (D0) occurred in northern Wyoming and eastern Kansas, where rainfall amounts were up to 3 inches above normal. Conversely, dry conditions resulted in the expansion of extreme drought (D3) in southwest Nebraska and western Wyoming, while severe and moderate drought expanded in southern Wyoming and Colorado. Abnormal dryness was also expanded in eastern Colorado.
West
Cooler temperatures dominated the West, with departures ranging between 1 to 10 degrees below normal. Much of the interior West experienced temperatures between 4 to 10 degrees below normal. In contrast, above-normal temperatures were observed across the eastern portions of the Southwest and in parts of Montana.
Precipitation varied across the region with beneficial amounts falling in parts of the Southwest. Moderate to extreme drought were improved in eastern New Mexico. Conversely, below-normal precipitation resulted in the expansion of exceptional drought (D4) in southwestern New Mexico and moderate drought in northern Montana this week.
Looking ahead
From May 20 to 24, as the medium-range period begins Tuesday, a surface low-pressure system over the Mid-Mississippi Valley supported by strong upper-level energy will provide ample lift and instability for rain and thunderstorms in the Mississippi and Ohio Valleys.
The low is forecast to track east and spread rain and thunderstorm chances to the Mid-Atlantic in particular on Wednesday, and shifting into the Northeast later week as the low pivots northward. Elsewhere, some weak troughing aloft and frontal systems tracking through the Northwest next week could produce rounds of modest precipitation there. Most precipitation should be rain aside from the highest peaks.
Warm to hot temperatures are likely across the southeastern U.S. as the subtropical upper ridge reaches the region. Southern Texas in particular will remain hot into Tuesday, with temperatures well into the 100s. Meanwhile, a trough will promote below normal temperatures across the northern tier, with highs only reaching the 50s in the north-central Plains on Tuesday. As the trough tracks east, cooler than average temperatures are likely in the eastern third of the U.S. under it, moderating temperatures in the South.
But upper ridging poking into the southwestern U.S. will raise temperatures to above normal there, expanding east across the Four Corners states by Thursday and into the southern Plains late next week. Highs will be well into the 100s in the Desert Southwest with temperatures nearing 100 in parts of Texas eventually.
The Climate Prediction Center’s 6- to 10-day outlook, valid May 25 to 29, favors above-normal precipitation across most of the U.S., with near-normal precipitation favored from southern California to Montana, as well as parts of the Midwest, northern New England, and northwest Alaska.
Below-normal precipitation favored in portions of the Midwest, from northern Minnesota to northern Michigan. Increased probabilities for above-normal temperatures are forecast for much of the West, and along the Gulf, while below-normal temperatures are favored for the central plains.
Rocky Bilotta is with the National Oceanic Atmospheric Administration and National Centers for Environmental Information.
