#Drought news (July 29, 2021): A robust Southwestern #monsoon2021 circulation delivered drought-easing rainfall but sparked localized flash flooding across large sections of the Four Corners States

Click on a thumbnail graphic to view a gallery of drought data from the US Drought Monitor.

Click here to go to the US Drought Monitor website. Here’s an excerpt:

This Week’s Drought Summary

A robust Southwestern monsoon circulation delivered drought-easing rainfall but sparked localized flash flooding across large sections of the Four Corners States, as well as the southern Great Basin, but critically dry conditions persisted across northern California and the Northwest. In the driest areas, wildfires—some sparked by lightning—dotted the landscape, with containment of some blazes hampered by high temperatures, low humidity levels, erratic winds, and abundant fuels. Farther east, another round of blistering heat across the northern Plains further stressed rangeland, pastures, and a variety of summer crops. The central and southern Plains also experienced some hot weather, although agricultural impacts were tempered by mostly adequate soil moisture reserves. Meanwhile, mostly dry weather covered the Midwest, continuing a trend that had developed in mid-July. Short-term dryness was not yet a concern in the previously well-watered lower Midwest. However, reproductive corn and soybeans in drier areas of the upper Midwest were subjected to increasing levels of stress, especially as temperatures began to rise. Elsewhere, Southeastern rain—which maintained abundant moisture reserves for pastures and summer crops—primarily fell from the Mississippi Delta to the southern Atlantic Coast…

High Plains

Drought’s footprint remained rather limited across Kansas, eastern Colorado, and southern Nebraska. Farther north and west, however, worsening drought impacts were observed across much of Wyoming and the Dakotas. According to the U.S. Department of Agriculture, topsoil moisture on July 25 was rated 87% very short to short in North Dakota, along with 82% in South Dakota and 79% in Wyoming. Rangeland and pastures were rated at least 60% very poor to poor in Wyoming and the Dakotas, led by North Dakota at 85%. On July 25, North Dakota was the national leader in oats rated very poor to poor (56%), along with soybeans (41%) and corn (39%). South Dakota led the nation, among major production states, in sorghum rated very poor to poor (31%). Nationally, the U.S. spring wheat crop was rated just 9% good to excellent and 66% very poor to poor on July 25, the lowest overall condition at this time of year since July 25, 1988, when the crop was categorized as 4% good to excellent and 72% very poor to poor. Harvest was underway for drought-ravaged crops on the High Plains; 3% of the spring wheat had been cut by July 25. Periodic extreme heat on the northern Plains has greatly aggravated drought impacts. During the most recent heat wave, high temperatures in South Dakota on July 27 soared to 108°F in Pierre and 107°F in Rapid City. In the latter location, that represented the highest temperature since August 29, 2012…

Colorado Drought Monitor one week change map ending July 27, 2021.

West

Further expansion of moderate to exceptional drought (D1 to D4) was introduced in parts of California and the Northwest, as agricultural, wildfire, and water-supply impacts continued to mount. Oregon’s third-largest wildfire in modern history, the Bootleg Fire, has burned more than 410,000 acres of timber and brush, but was more than 50% contained. California’s largest active blaze, the Dixie Fire, has scorched nearly 220,000 acres only about 15 miles northeast of the town of Paradise, which was devastated by the Camp Fire in 2018. Washington continued to lead the country in several drought-related agricultural categories, according to the U.S. Department of Agriculture, including topsoil moisture rated very short to short (99% on July 25), as well as very poor to poor ratings for rangeland and pastures (97%) and spring wheat (88%). In addition to Washington, at least two-thirds of the rangeland and pastures were rated very poor to poor on July 25 in Montana (91%), Arizona (82%), Oregon (80%), and Utah (69%). Montana rivaled Washington for agricultural drought severity, with topsoil moisture rated 97% very short to short and a nation-leading 70% of its barley rated very poor to poor. Farther south, however, an active monsoon circulation delivered drought relief in the form of diurnal showers and thunderstorms, some heavy. Up to one category of improvement was introduced in parts of Arizona, New Mexico, southwestern Colorado, and southern sections of Utah and Nevada. In Arizona, Tucson received more rain in 6 days (4.20 inches fell from July 20-25) than during all of 2020, when annual precipitation of 4.17 inches was the lowest on record. Despite the positive effect of monsoonal showers on surface conditions (e.g. improved vegetation health, topsoil moisture, and streamflow), serious long-term, underlying drought persisted, with obvious impacts on groundwater and reservoirs. The surface elevation of Lake Mead, on the Colorado River behind Hoover Dam, fell to a new record low—1,067.59 feet above sea level—on July 23. In Utah, the surface elevation of the Great Salt Lake fell below 4,191.4 feet in late July, breaking the previous record low set in 1963…

South

Arkansas, Louisiana, and Mississippi remained free of dryness and drought, while only small patches of abnormal dryness (D0) and moderate drought (D1) were noted in Oklahoma, Texas, and Tennessee. Most Southern crops continued to fare well amid plentiful rainfall and relatively mild temperatures. On July 25, three-quarters (75%) of the nation’s peanuts were rated in good to excellent condition, according to the U.S. Department of Agriculture, along with 73% of the rice and 61% of the cotton…

Looking Ahead

Cooler air will overspread the northern Plains and upper Midwest, though many drought-affected areas will remain in need of moisture. Large sections of the central and southern Plains will also remain mostly dry, accompanied by some of the hottest weather of the summer. Farther east, periodic showers and thunderstorms will affect the Great Lakes and Northeastern States. Meanwhile, hot, humid weather will linger into the weekend across the South, where an approaching cold front will generate showers and thunderstorms. Elsewhere, the Southwestern monsoon circulation will remain active, with beneficial showers dampening interior sections of the western United States as far north as Wyoming and southern Idaho.

The NWS 6- to 10-day outlook for August 3 – 7 calls for the likelihood of above-normal temperatures in Alaska, southern Florida and from the Pacific Coast to the northern Plains and upper Midwest, while cooler-than-normal conditions will cover much of the southeastern half of the country. Meanwhile, near- or below-normal rainfall across most of the United States should contrast with wetter-than-normal weather in a few areas, including western Alaska, the southern Atlantic region, the southern Plains, and the Northwest.

US Drought Monitor one week change map ending July 27, 2021

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