The storm track remained active across much of the contiguous U.S. this week. Much of the Northern Tier states experienced beneficial rainfall and near to below-normal temperatures, predominantly leading to drought improvements from the Pacific Northwest to the Northern Plains. Storm systems and clusters of thunderstorms also resulted in some improvements from the Mississippi Valley to the East Coast.
However, where the heaviest rains did not fall, there was some deterioration and slight expansion of abnormal dryness or drought conditions, particularly in parts of the Southeast and Ohio and Tennessee Valleys. Above-normal temperatures and below-normal precipitation was the main story across much of the southwestern CONUS, extending into Texas, leading to general persistence and degradation of drought conditions.
South
Short-term (30- to 60-day) rainfall deficits continue to mount across parts of the Lower Mississippi and Tennessee Valleys. Coverage of D0 (abnormal dryness) was generally expanded, although coverage is sporadic. Seasonal temperatures in these areas helped keep evapotranspiration rates at bay this week. However, daily soil moisture anomalies continue to become more negative, particularly over the past couple of weeks from northern Louisiana, extending northeastward toward the Tennessee Valley, as several locations have seen continued declines in surface moisture.
Similar to the Carolinas, these areas will need to be watched in the coming weeks, as potentially excessive heat and below-normal precipitation is forecast through the end of the month. Drought deterioration is also warranted across much of Texas, which saw another week of much above-normal temperatures, high winds, and below-normal precipitation. Some of these degradations extended into western Louisiana also. However, in eastern Louisiana, a cluster of thunderstorms provided some relief to abnormally dry (D0) and moderate drought (D1) areas. Improvements are also warranted in western Oklahoma, particularly in areas that received at least 1 inch rainfall surpluses this week. Some 2-category improvements occurred in areas where year-to-date precipitation deficits declined and daily soil moisture estimates improved to near-normal down to 200 cm.
Midwest
The Upper Midwest remained cooler than normal and generally wetter than normal, leading to some improvements in abnormally dry (D0) areas. Conversely, parts of the Corn Belt and Ohio Valley have started to dry out, as precipitation has been hit-or-miss in recent months, pushing short-term deficits to increase further (60-day rainfall deficits of more than 3 inches in many locations). As such, targeted expansion of D0 was warranted in parts of Kentucky, Indiana, Illinois, and Missouri. In addition, root zone soil moisture has fallen below the 20th percentile of the historical distribution (NASA SPoRT) along with nearby 7-day average stream flows, which have fallen below-normal (ranked between 10th to 24th percentiles by the end of the valid period – 6/14).
High Plains
Much of the High Plains Region has seen beneficial rainfall and temperatures averaging near to below-normal over the past 30 days. However, above-normal temperatures finally crept in this week, as temperatures ran more than 3°F above-normal for much of the region. Despite the above-normal temperatures, precipitation was also above-average for many locations, warranting broad 1-category improvements in the drought depiction where more than 1 inch 7-day surpluses were observed and where longer-term deficits were appreciably diminished. Only areas in southwestern Colorado and just east of the Front Range in Wyoming experienced some degradation, as temperature anomalies were highest in those areas (6°F to 9°F above-normal). Also, high winds have helped to exacerbate ongoing drought in those locations.
West
Much of the Northern Tier of the U.S. from the Pacific Northwest to the Northern Plains has seen marked improvements in recent months due to a persistent storm track and near to below-normal temperatures. That same pattern continued this week and continued to eat away at long-term precipitation deficits and indicators, such as groundwater. Additionally, some high-elevation locations have even picked up additional snowpack and stream flows are running near to much above-normal over the past 28 days.
Given the wet conditions in recent months and the continuation of the active storm track, broad improvements are warranted again this week. The only exception is parts of north-central Montana, where precipitation has generally missed many areas near the Golden Triangle in recent months, warranting some slight degradation this week, as precipitation again missed these areas. Elsewhere in the Western Region, despite the much above-normal temperatures, a general status quo depiction was warranted, the exception being Nevada and New Mexico.
Despite some nearby monsoon precipitation in parts of New Mexico and Arizona, accumulations were not enough to change the severe (D2) to exceptional (D4) drought depictions in areas where the rains fell. Given the temperatures were running anywhere from 5°F to 10°F above-average, and coupled with windy conditions, additional degradations were made in parts of western and southern New Mexico. Additionally, CPC soil moisture continues to remain below the 5th percentile much of the region and nearby stream flows are averaging in the bottom 2 percent of the historical distribution.
