Serious drought worsens in western parts of High Plains

Hurricane Sally, Tropical Storm Beta make landfall in South

Category 2 Hurricane Sally made landfall on Sept. 16 near Gulf Shores, Alabama, around 4:45 a.m. CDT, with sustained winds near 105 mph. Torrential rainfall across southern Alabama and western Florida sparked major to record flooding, while wind-related damage and power outages were common. Once inland over the Southeast, Sally quickly weakened but continued to produce heavy rain, extending as far north as southern Virginia.

Mostly dry weather covered the remainder of the country, except for showers in the Pacific Northwest and heavy rain in the western Gulf Coast region associated with the arrival of Tropical Storm Beta along the middle Texas coast. Beta, the 23rd named storm of the Atlantic hurricane season—behind only 28 tropical cyclones in 2005—made landfall at 10 p.m. CDT on Sept. 21 near Port O’Connor, Texas, with sustained winds near 45 mph. Meanwhile, drought remained entrenched across much of the western half of the country and parts of the Northeast. In the latter region, growing season-ending freezes (starting Sept. 19) may limit re-growth of drought-stressed pastures, even if widespread precipitation returns during autumn. Western wildfires continued to degrade air quality across a vast area, with approximately six dozen fires in various stages of containment by Sept. 22.

High Plains

Western portions of the High Plains continued to experience serious drought impacts, including severely stressed rangeland and limited soil moisture for the germination and establishment of recently planted winter wheat. On Sept. 20, according to USDA, topsoil moisture was rated at least one-half very short to short in Colorado (68%), Wyoming (65%), Nebraska (52%), and South Dakota (51%). On the same date, Wyoming led the region with rangeland and pastures rated 71% very poor to poor, followed by Colorado at 51%. Colorado led the nation—among major production states—in very poor to poor ratings for corn (35%). Most of the region’s weekly changes indicated worsening drought, amid mostly dry weather and above-normal temperatures.

South

Tropical Storm Beta made landfall on Sept. 21 along the middle Texas coast, resulting in eradication of dryness (D0) and moderate drought (D1) in the western Gulf Coast region. Torrential rain fell mainly north of Beta’s center of circulation, including parts of the Houston metropolitan area. Numerous reports of at least 10 inches of rain were received from Harris County, Texas, where Houston’s William P. Hobby Airport netted 12.24 inches from Sept. 20-22. Farther inland, additional improvements were introduced across central Texas in the wake of last week’s heavy rain, as drought impacts further faded. Meanwhile, a pesky area of dryness (D0) and moderate drought (D1) remained centered over Mississippi, with some further intensification noted. On Sept. 20, USDA topsoil moisture in Mississippi was rated 56% very short to short. Sept. 1-22 rainfall totals in Mississippi included 0.10 inch (5% of normal in Vicksburg and 0.22 inch (9%) in Meridian. (Sept. 23-24 rainfall in Mississippi and neighboring states associated with the remnants of Beta fell too late to be considered for this week’s report.) Elsewhere, ongoing dry weather in western sections of Texas and Oklahoma led to some modest expansion of dryness (D0) and moderate to extreme drought (D1 to D3). For the year to date through Sept. 22, precipitation in Midland, Texas, has totaled just 6.84 inches (62% of normal). Dalhart, Texas, is faring about as poorly, with 8.81 inches (60% of normal) falling from Jan. 1 – Sept. 22. The Vegetation Health Index (VHI) indicates that rangeland and pastures are significantly stressed across large sections of the southern High Plains, including much of western Texas.

Midwest

Mostly tranquil weather prevailed in the wake of the previous week’s significant precipitation event. However, recent rain bypassed a large area stretching from east-central Missouri into southwestern Ohio. A new area of short-term moderate drought (D1) was introduced in west-central Indiana, while dryness (D0) was broadly expanded where little rain has fallen for more than a month. Sept. 1-22 rainfall totaled just 0.04 inch (2% of normal) in Indianapolis, Indiana, and 0.50 inch (22%) in Saint Louis, Missouri. An area farther north, mainly in eastern Minnesota and northwestern Wisconsin, is also being monitored for the need to introduce abnormally dry conditions. Meanwhile, patchy dryness (D0) and moderate drought (D1) conditions exist in northern Minnesota, where Duluth reported a Jan. 1 – Sept. 22 precipitation sum of 14.62 inches (61% of normal).

West

Much-needed precipitation began to overspread the Pacific Northwest, signaling the change in seasons that should eventually deliver drought relief. For now, though, the Northwestern precipitation merely stabilized conditions in some areas and aided wildfire containment efforts. The Northwestern rain led to a daily-record sum of 1.14 inches on Sept. 18 in smoke-plagued Eugene, Oregon. The National Weather Service office in Seattle, Washington, reported a record-setting total (1.35 inches) for Sept. 19. However, the remainder of the West remained mostly dry. Ground reports and the Vegetation Health Index (VHI) continued to indicate severe stress on native vegetation, as well as rangeland. Very poor to poor ratings were indicated by USDA on Sept. 20 on at least 40% of rangeland and pastures in every Western State except Idaho, led by Oregon (84% very poor to poor). On the same date, topsoil moisture was at least 60% very short to short in every Western State except Arizona, led by New Mexico (91% very short to short). Water Year 2020 (Oct. 1, 2019 – Sept. 30, 2020) will soon end, with preliminary summaries indicating a dire drought situation in much of the region and some areas continuing to observe drought expansion or intensification. More than six dozen wildfires remained active across the West, with the greatest concentration of fires (and poor air quality) persisting in the Pacific Coast States. The latest wildfires to surpass 100,000 acres of vegetation burned were both in California: Bobcat Fire, northeast of Pasadena, less than 20% contained, and the August Complex West Zone, near Covelo, about 40% contained.