Rain has helped ease drought concerns
The latest U.S. Drought Monitor issued July 24 saw improvement in drought-related conditions across areas of the Southeast, South, Midwest, central and northern Plains, Intermountain West, and Desert Southwest, where short-term precipitation accumulations (past 30-day period) have helped to improve drought-related conditions.
For the week, the most significant rainfall accumulations were observed across northern Kansas and areas of the Midwest including Missouri, Iowa, Illinois, and Indiana where accumulations ranged from 3 to 10+ inches, with the highest accumulations observed in northeastern Kansas.
On the map, improving conditions over the past 30 to 60 days led to reduction in areas of drought in the Plains states, Kansas to North Dakota, as well as across drought-affected areas across the Midwest. In the South, drought conditions continued to improve in Texas, including in the Trans-Pecos region in western Texas where short and mid-term composite drought indicators are showing improving conditions in terms of precipitation, soil moisture, and vegetation health.
In the West, conditions were generally dry regionally, however, some isolated monsoon thunderstorms provided a much-needed boost in moisture (2 to 3 inch accumulations during the past week) to drought-affected areas of east-central and southeastern Arizona as well as lesser accumulations observed in central and northern Arizona.
In terms of reservoir storage in the West, California’s reservoirs continue to be at or above historical averages for the date (July 22), with the state’s two largest reservoirs, Lake Shasta and Lake Oroville, at 105% and 117% of average, respectively. In the Southwest, the U.S. Bureau of Reclamation is reporting (July 21) Lake Powell at 31% full (47% of average for the date), Lake Mead at 31% full (52%), and the total Colorado system (July 20) at 39% of capacity (compared to 45% of capacity the same time last year).
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
Improvements were made in the Hill Country and Trans-Pecos regions of Texas in response to improving conditions during the past 30 to 90 days. In these regions, targeted improvements were made in all drought categories (D1-D4). The western extent of the region, including much of Texas and Oklahoma, experienced temperatures ranging from 1 to 5 degrees Fahrenheit below normal.
Texas reservoirs are reported to be 80% full, with many in the eastern part of the state in good condition (over 90% full), while numerous others in the western portion of the state continue to experience below-normal levels, according to Water Data for Texas (July 23). In terms of streamflow activity (July 23), the U.S. Geological Survey is reporting well above normal streamflows (>90th percentile) across areas of central and eastern Texas and eastern Oklahoma while areas of the Texas Gulf Coast and South Texas Plains are experiencing below normal levels (1st to 24th percentile range).
Midwest
Widespread improvements were made across the region in response to beneficial rainfall observed this week as well as during the past 30-day period.
Storms during the past week delivered accumulations ranging from 1 to 6 inches, with the heaviest amounts observed in isolated areas of Missouri. On the map, improvements were made in Minnesota and Iowa. For the week, average temperatures were below normal (2 to 12 degrees) across the northern tier of the region, while the southern extent saw positive anomalies ranging from 1 to 6 degrees above normal.
High Plains
Improvements were made in the region, namely in central northern Kansas, southeastern Nebraska and South Dakota, where shorter-term precipitation (past 30 to 60 days) was normal to above normal. Additionally, these areas were showing improvements in other drought indicators including soil moisture, streamflow activity, and crop-related vegetation health indices.
Conversely, conditions degraded on the map in areas of central South Dakota as well as in northern North Dakota, where dry conditions have prevailed during the past 30 to 60 days.
Light-to-heavy rainfall accumulations (ranging from 1 to 10 inches) were observed, with the heaviest amounts impacting northern Kansas and southeastern Nebraska. Below-normal average temperatures (ranging from 1 to 8 degrees) were logged across most of the entire region.
West
Out West, generally dry conditions prevailed over much of the region with the exception of isolated areas of the Four Corners states, which observed monsoon-related thunderstorm activity with accumulations ranging from 1 to 4 inches.
Isolated areas of the Pacific Northwest and eastern Plains of Montana and Wyoming observed isolated shower activity with accumulations generally of less than 2 inches. On the map, persistent dry conditions led to expansion of areas of drought in western Wyoming, and in eastern and southwestern Montana.
For the week, average temperatures were mainly below normal with anomalies ranging from 2 to 10 degrees and the greatest departures logged were observed in east
Looking ahead
The NWS Weather Prediction Center 7-Day Quantitative Precipitation Forecast calls for relatively dry conditions across the western U.S., areas of the South, and southern Plains. Elsewhere, light-to-moderate accumulations are expected across areas of the central and northern Plains, Northeast, and the Gulf Coast region of the South and Southeast.
The Climate Prediction Center’s 6-10-day outlooks call for a moderate-to-high probability of above-normal temperatures across most of the conterminous U.S. In terms of precipitation, there is a low-to-moderate probability of above-normal precipitation across the Pacific Northwest, northern portions of the Intermountain West, central and northern Plains, Gulf Coast region, and much of the Eastern Seaboard.
David Simeral is with the Western Regional Climate Center.
