Nationwide
[inline_image file=”fa29b60ba4cd6dfe574ba8b0f761ff7c.png” caption=”20220503_usdm.png”]
This U.S. Drought Monitor (USDM) week was marked by ongoing active weather across areas of the conterminous U.S., including the Pacific Northwest, Northern Rockies, Plains, Lower Midwest, and isolated areas of the South and Southeast.
[inline_image file=”35cd1c6017de4f29ed900a72c0a5128d.png” caption=”Pasture May 5 2022.PNG”]
The most severe weather was observed across the Central Plains and areas of the Midwest, where numerous tornadoes touched down in areas including eastern Kansas, southeastern Nebraska, and northern Illinois. Widespread heavy rainfall accumulations were observed, ranging from 2 to 7 inches, with the heaviest accumulations in eastern Nebraska. The rainfall events provided much-needed moisture to the region-boosting soil moisture levels across parched areas from Kansas to South Dakota.
In the West, fast-moving storm systems delivered late-season high-elevation snowfall to the Cascades of northern Oregon and Washington, the Northern and Central Rockies, and areas of the northern Great Basin. The highest snowfall totals (8 to 12+ inches) were observed in the Salmon River Mountains of Idaho, the Ruby Mountains of northeastern Nevada, and the Wind River Range of Wyoming. In California and the Southwest, conditions were dry during the past week, with strong winds observed across the region.
The windy, dry conditions exacerbated fire-weather conditions in Arizona and New Mexico, where several large early-season wildfires are impacting the region. In northern New Mexico, the Hermits Peak Fire, situated east of Santa Fe in the Sangre de Cristo Mountains, has burned 147,909 acres and is only 20 percent contained (May 4), according to the National Interagency Coordination Center.
On the water-resource front, the Colorado River Basin water situation continues to deteriorate due to the long-term impacts of drought, with water levels at Lake Powell and Lake Mead currently at 24 percent full and 31 percent full, respectively. With Lake Powell’s water surface elevation currently at 3,522 feet, it is quickly approaching the 3,490-foot threshold level at which Glen Canyon Dam can continue to generate hydropower. The U.S. Bureau of Reclamation (USBR) announced (May 3) two urgent drought response actions to help bolster water levels at Lake Powell. The plan includes additional upstream releases from the Flaming Gorge Reservoir (~500,000 acre-feet [kaf] of water) as well as reducing Glen Canyon Dam’s annual release volume from 7.48-million acre-feet to 7 million acre-feet.
In terms of this week’s map, short-term precipitation led to targeted improvements in the Pacific Northwest, Central Plains, South, and the Southeast, while degradations were registered in the Southwest, Texas, Southeast, and the Mid-Atlantic.
The West
[inline_image file=”0f3a67c2d589de67eeb6649f77ac38f1.png” caption=”20220503_west_text.png”]
Out West, several storm systems moved through the northern tier of the region, bringing light to moderate snowfall accumulations to the higher elevations of the Cascades, northern Great Basin, and the Central and Northern Rockies, as well as light rainfall to coastal areas and low-lying inland valleys of Idaho, Oregon, and Washington.
Improvements were made in areas of Moderate Drought (D1), Severe Drought (D2), Extreme Drought (D3), and Exceptional Drought (D4) in Oregon in response to a combination of factors, including normal to above-normal SWE, recent storm events, and improved soil moisture levels and streamflows. Likewise, improving conditions in northern Wyoming led to the removal of areas of Extreme Drought (D3) in the Big Horn Mountains, where the current SWE is 108 percent of the median.
Elsewhere, conditions deteriorated on the map in northwestern Arizona and across much of New Mexico. Looking at snowpack data across the West at a regional scale (2-digit HUC), the NRCS SNOTEL network (May 3) reported the following median SWE levels: Pacific Northwest 111 percent, Missouri 99 percent, Souris-Red-Rainy 116 percent, California 60 percent, Great Basin 62 percent, Upper Colorado 76 percent, Arkansas-White-Red 50 percent, Lower Colorado 36 percent, and the Rio Grande 33 percent. According to NRCS National Water and Climate Center’s reservoir summary report (April 1), statewide reservoir storage levels were below average in all western states, with the exception of Washington state.
In California, the state’s two largest reservoirs are at critically low levels moving into the dry season, with Shasta Lake currently at 40 percent of total capacity on May 3 and Lake Oroville at 55 percent of capacity. In Southern California, the Metropolitan Water District of Southern California announced (April 27) that one-third of its users will be subject to restrictions limiting outdoor watering to one day per week to reduce water usage.
The High Plains
[inline_image file=”7d2a0988021f4cb9a011e205134278c0.png” caption=”20220503_high_plains_text.png”]
On this week’s map, widespread improvements were made in South Dakota, Nebraska, and Kansas in response to significant rainfall accumulations that helped to improve soil moisture levels and boosted streamflow levels.
Rainfall totals for the week ranged from 2 to 8+ inches, with the highest totals observed in central South Dakota, eastern and central Nebraska, and northern Kansas. However, some drought-stricken areas of the region, including extreme southeastern South Dakota, northeastern Nebraska, and central Kansas, largely missed out on this week’s storms.
In the eastern plains of Montana, improving conditions (precipitation, soil moisture) led to a reduction in areas of Severe Drought (D2) and Extreme Drought (D3). However, it should be noted that recent improvements in eastern Montana are not uniform and many areas are still coping with the impacts (agricultural) of the longer-term drought situation. Average temperatures were below normal across the northern half of the region, with negative departures ranging from 2 to 10+ deg F below average and the greatest departures observed in eastern portions of the Dakotas. In the southern half of the region, average temperatures were 2 to 8 deg F above normal.
The South
[inline_image file=”b2d783534502ed7949579c8494edd238.png” caption=”20220503_south_text.png”]
In the South, conditions on the map were a mixed bag of improvements and degradations.
In southern Louisiana, isolated areas of light-to-moderate rainfall (2 to 4 inches) improved areas of Moderate Drought (D1), Severe Drought (D2), and Extreme Drought (D3), as well as eliminated pockets of Moderate Drought (D1) in northern Louisiana and southern Arkansas. In areas of Texas (Panhandle, north-central, west-central, Trans-Pecos), isolated bands of heavy rainfall (2 to 4 inches) helped improve drought-affected areas. Conversely, the combination of above-normal temperatures, dry soils, and increased evaporative demand led to degradation in areas of the Panhandle, southeastern Texas, and the Trans-Pecos.
In the Panhandle of Oklahoma, small areas of Exceptional Drought (D4) expanded in response to short-term rainfall deficits. Reports in this area include very poor rangeland conditions and local ranchers relying on supplemental feed for cattle. According to the latest USDA Oklahoma Crop Progress and Conditions report (May 2), wheat crop conditions were rated 51 percent poor to very poor, and soil moisture was 63 percent short to very short. For the week, average temperatures were mostly above normal (2 to 8+ deg F), with the greatest positive anomalies observed across Texas and western Oklahoma. — UNL Drought Monitor
[inline_image file=”7610244a07395f9addbb2decfa77c07b.png” caption=”season_drought (16).png”]
[inline_image file=”0147abb3becd123576cfba33be852c8c.png” caption=”610prcp.new (32).gif”]
[inline_image file=”168af743ff4de179f67867c87a6ed29d.png” caption=”610temp.new (34).gif”]
