This U.S. Drought Monitor saw improvements on the map in drought-affected areas of the Southwest, northern Plains, and the Midwest while conditions deteriorated in areas of the Pacific Northwest, eastern Plains of Colorado and Montana, southern Plains, and the South.
In the Pacific Northwest, a combination of factors (below-normal snowpack conditions, short-term dryness, low streamflows) led to expansion of areas of abnormally dry and moderate drought in western portions of Oregon and Washington. Poor snowpack conditions in the northwestern and west-central part Montana led to expansion of areas of extreme drought where some SNOTEL stations were reporting record or near-record low snow-water equivalent levels.
Drier-than-normal conditions during the past 30-to 90-day period in addition to low streamflows, declining soil moisture, and impacts to crops led to expansion of areas of moderate drought and severe drought in Oklahoma and Kansas. Conversely, wetter-than-normal conditions have prevailed during the past 30 to 60 days in portions of the Midwest leading to widespread improvements across drought-affected areas of Iowa, Minnesota, Wisconsin, and Michigan.
Likewise, improvements were made on the map in areas of the Southwest (Arizona and New Mexico) in response to beneficial precipitation received across much of the region since Jan. 1. Elsewhere in the West, below-normal SWE levels have persisted in the mountain ranges of Montana and northeastern Wyoming.
The U.S. Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the U.S. Department of Agriculture and the National Oceanic Atmospheric Administration. (Map courtesy of NDMC.)
South
Light-to-moderate rainfall (up to 4 inches) was observed across isolated areas of the region with the heaviest accumulations logged in eastern Texas, northern Louisiana, southwestern Arkansas, and central Mississippi. Average temperatures were near to slightly above normal in southern portions of Texas and Louisiana, while areas in the northern half of the region were generally cooler-than-normal (1 to 8 degrees Fahrenheit).
On the map, conditions deteriorated in areas of the south Texas plains and Edwards Plateau in response to a combination of factors including short-term dryness (past 30 to 90 days), low streamflows, declining soil moisture levels, and stressed vegetation. Statewide reservoir conditions in Texas were at 73.9% full as of April 24. Lingering low reservoir conditions are being reported in the western half of the state in the San Angelo and San Antonio areas, according to Water Data for Texas.
Dry conditions led to another round of degradations on the map across the northern portion of Oklahoma. According to the latest U.S. Department of Agriculture Oklahoma Crop Progress and Condition report (April 21), the statewide soil moisture (topsoil) condition was rated 46% short to very short.
Midwest
Light-to-moderate precipitation accumulations (generally under 2 inches) were observed in the region with the heaviest accumulations logged in isolated areas of southern Minnesota, southern and northeastern Iowa, southeastern Missouri, southern Illinois, and southwestern Indiana.
Average temperatures for the week were below normal (2 to 6 degrees Fahrenheit) across the western half of the region with the greatest anomalies observed in eastern Iowa and central Illinois. In the eastern portion of the region, the average temperature hovered within a few degrees of normal.
Improvements were made in drought-affected areas of southern Minnesota, eastern and northern Iowa, northern Missouri, Wisconsin, southern Illinois, and northern Michigan. Despite improving conditions, two areas of extreme drought remains in the northeastern part of Iowa due to the lingering impacts of the longer-term drought situation with 12-month precipitation deficits ranging from 12 to 16 inches.
According to the latest USDA Iowa Crop Progress and Condition report (issued April 22), the statewide soil moisture (topsoil) condition was rated 37% short to very short and 60% adequate. In southern Missouri, areas of drought expanded on the map where dry conditions have prevailed in the shorter term (past 30 to 90 days) and have led to a significant decline in streamflow levels with numerous rivers and creeks reporting very low flows during the past week.
High Plains
On this week’s map, one-category degradations were made in Kansas where precipitation has been below normal during the past 90-day period with the greatest departures (4 to 5 inches) observed in south-central and eastern Kansas. Stream gages on numerous creeks and rivers in central and eastern Kansas were reporting much below-normal flows, according to the U.S. Geological Survey. In terms of impact, the USDA reported April 21 that 26% of the winter wheat crop in Kansas was rated in poor to very poor condition.
Average temperatures across the Plains states have been well above normal levels (ranging from 4 to 8 degrees Fahrenheit) during the past 90 days with the greatest anomalies observed in far eastern portions of the region.
In North Dakota Climate Division 6 (east central division), the December to March period was the second warmest on record with an +11.6 degrees Fahrenheit anomaly, according to National Oceanic Atmospheric Administration and National Centers for Environmental Information. Shorter-term improvements in drought-related conditions led to reductions in areas of abnormally dry and moderate drought in northeastern Nebraska and northwestern South Dakota.
For the week, average temperatures were below normal (2 to 10+ degrees Fahrenheit) with the greatest departures observed in western portions of the Dakotas and Nebraska as well as along the eastern plains of Wyoming and Montana.
The region was generally dry during the past week except for a few areas that benefitted from isolated shower activity in northeastern Kansas, north central and northeastern Nebraska, and southwestern South Dakota.
West
Improvements were made across areas of central and southeastern Arizona and in southern New Mexico in response to a re-assessment of overall conditions looking at numerous drought metrics at various time scales.
Since Jan. 1, much of Arizona as well as western and northern portions of New Mexico have observed precipitation levels ranging from normal to well above normal. In contrast, below-normal precipitation has prevailed across much of eastern New Mexico.
Looking ahead
The National Weather Service’s Weather Prediction Center 7-Day Quantitative Precipitation Forecast calls for moderate-to-heavy precipitation accumulations ranging from 2 to 5+ inches across eastern portions of the southern and central Plains and lower Midwest. Lighter accumulations (< 2 inches) are expected in areas of the central and northern Rockies and Upper Midwest.
The NWS Climate Prediction Center’s six-to 10-day outlooks call for a moderate-to-high probability of above-normal temperatures across most of the conterminous U.S. where cooler-than-normal temperatures are expected.
In terms of precipitation, below-normal precipitation is expected across the eastern tier of the conterminous U.S. as well as out west in western Colorado, Utah, and southern Nevada. Elsewhere, there is a high probability of above-normal precipitation across the Pacific Northwest, Northern California, eastern New Mexico, Texas, the Plains states, and the Upper Midwest.
David Simeral is with the Western Regional Climate Center.
