U.S. Drought Monitor discussion for Thursday, August 28.
On August 21, Hurricane Erin passed about 200 miles east of North Carolina’s Outer Banks, with minimal weather impacts aside from gusty winds along portions of the Atlantic Seaboard. A peak northerly wind gust to 43 mph was clocked on Cape Hatteras, North Carolina. More broadly, Erin resulted in an extended period of Atlantic coastal impacts, such as life-threatening surf and higher-than-normal tides. Meanwhile, patchy downpours maintained adequate to locally excessive soil moisture in much of the upper Midwest, while locally heavy showers dotted the central and southern Plains and the lower Southeast. However, mostly dry weather in many other areas across the central and eastern U.S. led to declining topsoil moisture reserves, especially where combined with late-summer heat. Cooler air arrived, however, late in the drought-monitoring period, starting in the North and soon reaching all areas east of the Rockies but the northern High Plains and the Deep South. Meanwhile in the West, hot, mostly dry weather prevailed until late in the period, when shower activity increased and began to spread northward..
A generally cool weather pattern will persist in most areas of the country for the remainder of the month. However, heat will gradually return across the West, with temperatures in parts of the Desert Southwest topping 110°F by the last day of August. East of the Rockies, anomalous warmth should be limited to the northern High Plains and the Deep South, mainly from southern Texas to southern Florida. Meanwhile, much of West will experience a drying trend, although late-month downpours in portions of the central and southern Rockies could lead to flash flooding and debris flows, especially on burn-scarred hillsides. Heavy, late-month rainfall (locally 2 to 4 inches or more) may also affect an area stretching from the mid-South to the southern Atlantic Coast. In contrast, little or no rain will fall during the next 5 days from the middle Mississippi Valley into the middle Atlantic States.
The NWS 6- to 10-day outlook for September 2 – 6 calls for the likelihood of below-normal temperatures in the central and eastern U.S., aside from warmer-than-normal weather in northern Maine, peninsular Florida, and the western Gulf Coast region. In contrast, late-summer warmth will dominate the West, except in the central and southern Rockies. Meanwhile, near- or above-normal precipitation across most of the country should contrast with drier-than-normal conditions in parts of the Pacific Northwest.
High Plains region.
The High Plains region experienced a mix of drought improvement and deterioration. The region’s most significant drought exists across western sections of Colorado and Wyoming. On August 24, statewide topsoil moisture—as reported by the U.S. Department of Agriculture—was rated 70% very short to short in Wyoming. During the drought-monitoring period, the most significant drought improvement occurred in central Colorado, although there were also targeted improvements in Kansas, Nebraska, and South Dakota.
Midwest region.
Continuing a recent theme, drier-than-normal weather in the southern and eastern Corn Belt generally contrasted with locally heavy showers (and ample soil moisture reserves) farther north and west. By August 24, the U.S. Department of Agriculture rated statewide topsoil moisture at least one-half very short to short in Kentucky (66%), Michigan (55%), and Ohio (51%). Statewide values were above 40% very short to short in Illinois and Indiana. Despite a turn toward cooler weather, coverage of abnormal dryness (D0) and moderate drought (D1) broadly increased from Missouri into the Ohio Valley and lower Great Lakes region.
Northeast region.
Aside from a band of rain across parts of New York and Pennsylvania into southern New England, mostly dry weather prevailed. Consequently, moderate to severe drought (D1 to D2) worsened across northern New England, extending into northern New York. On the other side of the rain band, abnormal dryness (D0) expanded in West Virginia and environs. On August 24, topsoil moisture in agricultural areas was rated at least 55% very short to short in all six New England States, as well as New York, according to the U.S. Department of Agriculture.
South region.
Flash-drought conditions across the mid-South contrasted with the arrival of heavy rain in Oklahoma and neighboring areas. On August 24, prior to the heavy rain, statewide topsoil moisture was rated 60% very short to short in Texas, along with 53% in Oklahoma. Portions of central and northwestern Oklahoma received 3 to 6 inches of rain during the drought-monitoring period. Meanwhile, topsoil moisture was rated more than one-half very short to short on August 24 in Arkansas (92%), Tennessee (63%), and Mississippi (53%). Aside from eastern Tennessee, southern Mississippi, and west-central Arkansas, where some heavy rain fell, conditions generally worsened across those three states, with broad expansion of abnormal dryness (D0) and moderate to severe drought (D1 to D2).
Southeast region.
Showery weather allowed for mostly improving conditions in a region with an already small drought footprint. As the monitoring period began, drought covered just over 3 percent of the Southeastern region. Some of the heaviest rain fell from Florida’s Gulf Coast northward to coastal South Carolina. Downtown Charleston, South Carolina, received 8.05 inches of rain on August 22-23.
West region.
A hot weather pattern gradually yielded to increasingly cloudy and showery weather. In most areas, however, showers were insufficient to result in significant drought relief, except in central Colorado and environs. Still, there were several episodes of significant weather, including a thunderstorm-fueled haboob on August 25 in Phoenix, Arizona, where high winds (clocked to 70 mph at Sky Harbor International Airport) and near-zero visibility in blowing dust led to travel and electrical disruptions. By August 26, at the end of the drought-monitoring period, shower activity began to shift farther north and east. In the Northwest, where hot, dry weather prevailed for much of the period, there was some drought expansion, with two previously separate areas of severe drought (D2) merging across eastern Washington. Some of the worst agricultural conditions in the country have been noted in recent weeks across Washington, with the U.S. Department of Agriculture reporting that 47% of the state’s rangeland and pastures were rated in very poor to poor condition on August 24. On the same date, Washington led the U.S. with 57% of its barley and 53% of its spring wheat rated very poor to poor.