Dry and hot weather story for the Southern Plains

Dry weather continued this week across much of the central U.S., especially from the southern Great Plains to the Mississippi River Valley and Corn Belt.

Flash drought conditions were occurring across a large area spanning from Texas northeastward to Oklahoma and southern Kansas, southern Missouri, Arkansas, northern Mississippi and portions of far western Tennessee. Due to the drier- and warmer-than-normal weather in most of these areas, drought and abnormal dryness expanded and intensified in many areas, as widespread adverse impacts to agriculture continued and fire danger continued to grow in some areas.

Hot and dry weather continued near the borders of the Dakotas with Minnesota, leading to worsening drought conditions. Widespread improvements occurred in some areas from Wyoming and the plains of eastern Colorado northeast into the Nebraska Sandhills and southern South Dakota, where either heavy rainfall this week improved conditions or conditions were reassessed following recent heavier rains.

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

Widespread expansion or worsening of ongoing drought or abnormal dryness occurred across the South, especially in parts of Texas, eastern Oklahoma and portions of Arkansas. Heavier rains, locally over 2 inches, fell in southeast Louisiana and southwest Mississippi. Otherwise, weather conditions were mostly drier, with many areas receiving less than a half inch of rainfall and some receiving none.

Temperatures were warmer than normal across most of the region, especially in Oklahoma and the northern half of Texas, where temperatures were 6 to 10 degrees Fahrenheit hotter than normal. This continued a very hot August across much of Oklahoma.

Degradations in drought conditions were especially prevalent in southwestern and northern Texas, deep south Texas and eastern Oklahoma, as ongoing hot and dry weather worsened conditions in areas already suffering a myriad of drought impacts.

Burn bans were enacted across much of western OklahomaStreamflow across much of central and western Oklahoma and northern Texas was quite low, along with low soil moisture and intense short-term precipitation deficits.

Midwest

Dry weather occurred across much of the southern half of the Midwest region this week. This led to widespread degradation of conditions in Missouri, especially in the south-central and southwest part of the state. Fire danger and drought impact to agriculture and other vegetation continued to worsen in southwest Missouri and neighboring Arkansas, leading to degrading conditions across much of this area.

Drought conditions also worsened in west-central Minnesota, where short- and long-term precipitation deficits mounted. Temperatures in the eastern half of the region were generally within 2 to 4 degrees of normal, while much of Minnesota, Iowa and western Missouri were 2 to 6 degrees warmer than normal. Scattered rains fell across parts of the Upper Midwest, locally exceeding 2 inches but mostly depositing a half inch or less of rain.

High Plains

A swath of 0.5 to 2 inches of rain fell from parts of western Nebraska and western Kansas into portions of Colorado and Wyoming. Scattered similar rain amounts also fell in portions of east-central and northern South Dakota, as well as in parts of central and western North Dakota.

The impacts of recent rainfall in southern South Dakota and the Nebraska Sandhills were re-evaluated this week, and widespread improvements were made as soil moisture and streamflow locally improved, while short-term rainfall deficits were alleviated. Long-term precipitation deficits and their impacts continued across much of this region, and abnormal dryness and long-term moderate drought remained.

Scattered improvements to drought also occurred from southern and eastern Wyoming into the western Dakotas and much of eastern Colorado. Short-term precipitation deficits improved in these areas, with some improvement in soil moisture and streamflow, leading to improvements in drought conditions.

Streamflow remains low across portions of the western High Plains region given the poor high elevation snows and warm temperatures during the water year. Temperatures across the region were hotter than normal, especially in Kansas, where temperatures ranged mostly from 6 to 10 degrees above normal, resulting in high atmospheric demand for moisture in southeast Kansas.

West

Locally heavy rains from the North American Monsoon fell in parts of Arizona, Utah and the Rocky Mountains in Colorado. Parts of Colorado to the west of the Front Range saw conditions improve given recent rainfall, though widespread short- and long-term drought remained across central and western Colorado.

In a few areas in south-central and southwest Colorado that missed out on heavier rains, long-term precipitation deficits grew even worse. Temperatures from 4 to 6 degrees above normal also kept atmospheric thirst high, and extreme and exceptional drought locally expanded. Short-term precipitation deficits and poor streamflow in some areas led to drought degradation in parts of northwest Montana. Moderate drought locally expanded in north-central Montana where short-term rainfall deficits grew and soil moisture declined in a few areas.

Recent precipitation in southwest Montana led to improvements in mid- to long-term precipitation deficits and overall conditions, and moderate drought coverage decreased.

Looking ahead

Through the evening of Sept. 7, the National Weather Service Weather Prediction Center is forecasting dry weather to continue across much of the central and south-central U.S., especially from southeast Nebraska through Oklahoma, Arkansas and western north Texas into southwest Texas and eastern New Mexico and Colorado.

Heavier precipitation amounts through Monday evening will likely be confined to parts of the southeastern and northern Lower 48. Heavy rain is forecasted, or occurring on Wednesday afternoon, in east-central and southeast Texas, while the remnants of Tropical Storm Edouard pass through.

Heavier precipitation amounts, mostly in the 0.75- to 2-inch range, are also forecast in parts of the Pacific Northwest, northern Idaho, northern parts of Montana and North Dakota, and from Minnesota southeastward across Wisconsin and the lower Great Lakes into Pennsylvania and New York.

The National Weather Service Climate Prediction Center’s 6- to 10-day outlooks, covering Sept. 8 to12, favors warmer-than-normal temperatures across much of the central and eastern U.S. The highest confidence for above-normal temperatures is centered around Kansas City and the mid-lower Missouri River Valley southward to the central and western Gulf Coast.

Near-normal temperatures are favored in the western half of the West, with below-normal temperatures slightly favored in western Nevada and adjacent parts of California and Oregon. Above-normal precipitation is favored across much of the Great Plains and western U.S., especially from the Continental Divide into the Great Basin and in northern Minnesota and environs.

Curtis Riganti is with National Drought Mitigation Center.