Hot and dry weather dominated over the southern Plains this week, while the northern tier of the U.S. as well as the Southeast saw some precipitation, this week's Drought Monitor report, released Thursday, says.
Drought monitor author Richard Heim of NOAA says cool fronts also brought thunderstorms to the central Plains, while drought remained in the West and continues to tighten on the Pacific Northwest.
About 38.9% of the contiguous U.S. is in some form of drought or dryness currently, compared to 36% last week and 47.5% one year ago. About 2.8% is in the most extreme rating, compared to 2.8% last week and 3.9% one year ago.
Northeast, Mid-Atlantic, Southeast
In the Northeast and Mid-Atlantic region, areas received 1-2 inches of rain, with locally more than three inches, while other parts received little to no precipitation. With temperatures averaging below normal, no change was made to the drought depiction there.
In parts of the Southeast, rainfall was widespread. As of July 27, 62% of the topsoil and 45% of the subsoil in Louisiana was rated short or very short of moisture. D0 was extended into northwestern Louisiana, to reflect dryness for the last 30-60 days; across southern Louisiana, which has precipitation deficits out to the last 90 days; and into southwest Mississippi, where deficits extended even further back in time.
July 27 USDA National Ag Statistics Service reports indicated 38% of the topsoil and 39% of the subsoil short or very short of moisture in North Carolina, with 37% of the pasture and rangeland rated in poor to very poor condition. Conditions were worse in South Carolina, where 73% of the topsoil and 67% of the subsoil were short or very short of moisture, and 35% of the corn crop was rated in poor or very poor condition.
Low streams, drying soil moisture, and spotty rainfall prompted the expansion of abnormal dryness and moderate drought in west central South Carolina and the Upstate.
Northern and Central Plains and Midwest
Storms moving along cool fronts in the Northern and Central Plains and Midwest dropped two inches of rain in some areas, with locally over four inches, mostly in drought-free regions.
D0 was added in Minnesota, northern parts of Michigan, and northeast Wisconsin, however, to reflect recent dryness as well as longer-term deficits.
Showers and thunderstorms gave parts of Nebraska and Kansas over one inch of rain, while neighboring counties received little rain.
July 27 USDA NASS reports indicated that 30% of the topsoil and 26% of the subsoil in Nebraska was rated short or very short of moisture, and 35% of winter wheat was rated in poor to very poor condition, a result of dryness earlier in its growing season.
In Kansas, 24% of topsoil and 25% of subsoil was rated short or very short of moisture. While most crops in Nebraska were weathering the recent dry spell well, sandier soils were beginning to show signs of stress.
D0 expanded into central Kansas and southwestern to central Nebraska, and D0 ovals were added to parts of the Nebraska panhandle and southeast Nebraska.
Southern Plains, Southwest
In the Southern Plains, hot and dry weather continued across parts of eastern and southern Texas, increasing evaporation and the risk of wildfires.
July 27 USDA NASS reports indicated rapid drying of topsoil and subsoil moisture in eastern and southern Texas and the Trans-Pecos.
In the Northeast district, 54% of the topsoil and 47% of the subsoil were rated short or very short of moisture. The values were 57% and 49%, respectively, for the Southeast district, 63% and 37% for the Upper Coast district, 66% and 57% for the South district, and 48% and 56% for the Trans-Pecos district.
As a result, D0 was expanded across parts of eastern Texas, spots of D0 were added in southern Texas, and an oval of D1 introduced in northeast Texas. But most crops across the state were rated in fair to good condition, except 33% of oats and 20% of wheat were rated in poor to very poor condition.
In New Mexico, 52% of the topsoil and 39% of the subsoil was rated short or very short of moisture, but recent rainfall aided crop development, with most crops in fair to good condition.
West and Northwest
Frontal rains and leftover moisture from Hurricane Dolores brought above-normal precipitation to parts of California, Nevada, Montana, and the Pacific Northwest this week.
The heavier rainfall amounts ranged from half an inch to 2 inches, with less than half an inch common. This is the dry season for the Far West, so even minor amounts of rain equate to well above normal.
While the rains in southern California during the past couple weeks have caused local flooding and inhibited wildfire development, reservoirs saw no increase in storage.
The lack of mountain snowpack has contributed to record and near-record low streamflows across much of the Pacific Northwest, with tinder-dry conditions resulting in the closing of the forests in northern Idaho.
According to July 27 USDA NASS reports, topsoil and subsoil moisture continued to decline, with topsoil short or very short of moisture across 80% of Oregon, 65% of Washington, and 52% of Idaho, and subsoil short or very short of moisture across 80% of Oregon, 65% of Washington, and 46% of Idaho.
Pasture and range conditions were rated poor to very poor across 47% of Oregon, 41% of Washington, and 14% of Idaho, which were slight increases compared to the previous week.
Crop harvesting continued, and while most crops were in fair to good condition across the region, 32% of the winter wheat crop in Oregon was rated in poor to very poor condition.
The stream and soil moisture conditions prompted expansion of D3 across the Idaho panhandle and into eastern Washington, and the introduction of D3 and fill-in of D2 along coastal Oregon and Washington.
Warm stream temperatures due to low flows and hot weather caused fish trauma and disease, and fish kills, which prompted the closing of streams to all fishing along the Washington Cascades. D3 was added to the Washington Cascades to reflect these impacts as well as agricultural and water supply impacts.
In Idaho, the Salmon Falls Tract was shut down for the season on July 19th with an allotment that was estimated to be between the 6th and 10th of the 1910-2015 historic record, and a shutdown date that was much earlier than normal.
This shutdown cuts off irrigation water which will have a serious impact on agriculture in the region for the remainder of the season.
Source: Richard Heim, NOAA/NCEI - The U.S. Drought Monitor is produced through a partnership between the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration.