Widespread rain has helped ease drought footprint
Above normal precipitation and below normal temperatures resulted in another week of targeted improvements across portions of the Intermountain West, adding to recent precipitation totals that have continued to improve long-term drought conditions.
There is a mix of improving and worsening drought conditions across the Great Plains. Improvements are mainly confined to the western Great Plains, where widespread seven-day rainfall totals exceeded 200% of average for the week, further adding to short-term precipitation surpluses. From the eastern Great Plains to the Eastern Seaboard, seven-day rainfall surpluses are more scattered in nature, leading to only modest improvements in areas seeing the heaviest amounts. In areas that received below normal rainfall this week, drought worsened, as rainfall deficits continue to increase.
Several locations across Louisiana, Mississippi, and Tennessee experienced degradation this week, as the frontal boundary draped across the southern tier states did not result in enough precipitation to stave off degradation for those experiencing antecedent dryness. This is also the case in portions of central Texas and parts of the middle Red River basin, where targeted degradations are also warranted.
However, farther westward across western portions of the Southern Plains, pockets of heavy rainfall continued to add to 60-day precipitation surpluses, particularly for parts of the Texas and Oklahoma Panhandles. Rainfall has been plentiful in these areas in recent weeks and months. For example, Amarillo Texas recently set a new record of 20 days with measurable precipitation during May; the previous record being 15 days. In addition, Lake Meredith, located north of Amarillo has reached 45.8% of its capacity, its highest since 2001, according to Texas Water Development Board data.
A storm system over the Midwest and Great Lakes over the weekend did little to halt widespread degradation of conditions across the Midwest. Although some locations did experience modest improvements, mainly in areas seeing in excess of 2 inches of rainfall, degradation to moderate drought (D1) and expansion of abnormal dryness (D0) is widespread across the Corn Belt, the Lower Peninsula of Michigan, and the Upper Midwest.
High rates of evaporation from soils and vegetation over the past 1 to 2 months have resulted in large losses to soil moisture, with stream flows also dropping significantly across many of these same areas (falling below the 10th percentile of the historical distribution, particularly across the southern Great Lakes and the Corn Belt). There are many reports of browning and stressed vegetation, with several producers already resorting to supplemental feeding for their livestock due to reduced forage. Loss of yield remains a large concern for many.
Although much of the High Plains region received above-normal precipitation this week, the region as a whole is a tale of two halves. Improvement to the drought depiction is warranted across western portions of the central and northern Plains, where seven-day precipitation totals exceeded 200% of average across most areas, adding to precipitation surpluses in recent weeks and improving long-term drought indicators.
Conversely, deteriorating conditions are warranted across eastern parts of the High Plains region where heavy, convective rainfall was not enough to overcome predominantly near and above normal temperatures and high rates of evaporation from the soils and vegetation (known as evapotranspiration). For example, parts of South Dakota reported evapotranspiration rates from crops averaging around 0.25 inches per day, which varied slightly depending on the type of crop, essentially eliminating the effects of beneficial rainfall for several locations.
The Intermountain West is the beneficiary of another week of widespread above normal precipitation for many locations, with large portions of the Four Corners region, the Great Basin, and the southern and central Rockies also experiencing below normal temperatures. Improvements are warranted in locations where long-term drought indicators, such as groundwater, continue to improve. In addition, the above-normal snowpack from the active winter rainy season across much of the West continues to keep stream flows near and above average.
Looking ahead
According to the Weather Prediction Center, over the next six days (June 15 to 20) warm temperatures are forecast to build across central portions of the lower 48 states, with cooler temperatures forecast across much of the Intermountain West and the West Coast leading up to June 20. Generally seasonal temperatures are likely east of the Mississippi River. Rainfall is forecast across a large swath of the lower 48 states from the Pacific Northwest to the Southeast, and northward along the East Coast.
During the next 6 to 10 days (June 20 to 24), the Climate Prediction Center favors below normal temperatures across the western third of the lower 48 states, and across parts of the Mid-Atlantic coast and Appalachians. Above normal temperatures are favored for the Great Plains, Mississippi River Valley, Great Lakes, interior Northeast, and southern Florida. Above normal precipitation is indicated across northwestern and north-central portions of the lower 48 states, and across the Southeast and Mid-Atlantic states. Below normal precipitation is weakly favored across parts of southern Texas and extending into the Four Corners region, parts of the Midwest, and northern New England.
