Nationwide
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This U.S. Drought Monitor week saw widespread improvements across areas of the Midwest and eastern portions of the Central and Northern Plains states in response to beneficial rainfall. Rainfall accumulation in these areas ranged from 2 to 12+ inches leading to one-category improvements across areas of the Dakotas, Nebraska, Kansas, Iowa, Minnesota, and Wisconsin.
In the South, Hurricane Ida made landfall along the Gulf Coast of Louisiana on Sunday as a Category 4 hurricane with maximum sustained winds of 150 mph. The hurricane caused extensive infrastructure damage, including widespread power outages in Louisiana and Mississippi, impacting more than 1 million homes and businesses as well as stranding residents amongst the floodwaters.
In the West, dry conditions persisted across most of the region, with approximately 90 percent of the region currently categorized as “in drought.” In California, two major wildfires (Dixie and Caldor fires) continued to intensify and expand due to the dry and windy conditions. In El Dorado County, California, the Caldor Fire continued to rapidly spread this week, leading to the evacuation of residents in communities on the southern end of the Lake Tahoe Basin—including the City of South Lake Tahoe.
In addition to impacting fire conditions, the ongoing drought in California continues to strain the state’s water resources. This is reflected in the reservoir levels of California’s two largest reservoirs, Lake Shasta and Lake Oroville, which are currently at 43 percent and 34 percent of historical averages, respectively.
In the Southwest, Lake Powell is currently 31 percent full and Lake Mead is 35 percent full. The total Lower Colorado system is at 40 percent full, according to the U.S. Bureau of Reclamation, compared to 50 percent full at the same time last year.
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The West
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Currently, ~90 percent of the West region (including Colorado and Wyoming) is categorized as “in drought” on the map, with 54 percent in Extreme Drought (D3) or Exceptional Drought (D4).
Some improvements were made in New Mexico and Utah on this week’s map in response to the cumulative impact of this summer’s active monsoon and its associated short-term improvements to vegetative health, soil moisture, and streamflow activity. Elsewhere, degradations were made on the map in the eastern plains of Montana, southeastern Wyoming, southern Idaho, and central Oregon.
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In Northern California, dry and windy conditions led to further expansion and intensification of the Dixie and Caldor fires during the past week. According to CalFire, the Dixie Fire is now the second-largest wildfire in California history, while Caldor Fire is now the 15th largest. According to the National Interagency Coordination Center’s Incident Management Situation Report (Sept 1), the Dixie Fire had burned 819,956 acres (49 percent contained) and the Caldor Fire totals 199,632 acres (18 percent contained). During the past week, the Caldor Fire spread rapidly eastward up the Highway 50 corridor and into the Lake Tahoe Basin, leading to an evacuation of the largest town in the basin—South Lake Tahoe.
On a positive note, this summer’s monsoonal rains have led to some modest reservoir inflows in the Salt and Verde River system reservoirs in Arizona, where the total reservoir system was at 71 percent full (85 percent full one year ago) as of August 31. For the week, rainfall activity (accumulations generally <2 inches) across the region was restricted to isolated areas of Arizona and New Mexico and central and eastern Montana.
Average temperatures during the past week were slightly above normal (1 to 8 deg F degrees) across the southern half of the region, while cooler-than-normal temperatures were observed in northern portions ranging from 1 to 8 deg F below normal. According to NOAA National Centers for Environmental Information, Arizona experienced its 2nd wettest July on record as well as its 3rd wettest May-July period on record.
The High Plains
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On this week’s map, areas of the region—including eastern portions of the Dakotas, Nebraska, and Kansas—saw widespread improvements in drought-stricken areas experiencing Exceptional Drought (D4), Extreme Drought (D3), Severe Drought (D2), and Moderate Drought (D1).
The improvements were made in response to heavy rainfall during the past week (ranging from 2 to 5 inches) and minor improvements to soil moisture levels in some areas. Conversely, western portions of the Dakotas have continued to experience rainfall and soil moisture deficits which have severely impacted crops as well as pasture and rangeland conditions.
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According to the latest (August 29) USDA North Dakota Crop Progress and Condition report, pasture and range conditions across the state were rated 61 percent very poor and 24 percent poor, while stock water supplies were rated 58 percent very short and 31 percent short.
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According to the most recent (August 29) USDA South Dakota Crop Progress and Condition report, pasture and range conditions across the state were rated 48 percent very poor and 36 percent poor, while corn condition was rated 16 percent very poor and 29 percent poor.
In terms of NOAA NCEI’s climatological rankings, North Dakota observed its 11th driest (-3.11-inch anomaly) May-July period as well as its 3rd driest (-7.40-inch anomaly) August-July period on record. Similarly, South Dakota had its driest (-3.17-inch anomaly) May-July on record as well as its 7th driest (-5.45-inch anomaly) August-July period on record. — UNL Drought Monitor
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