We usually do a comparison of the current map with the map four weeks earlier. Today, instead of the second map, we'll go with the monitor's discussion of the American West and Southwest instead.
From the University of Nebraska - Lincoln, Apr. 8:
As the wet season begins to wind down in the West, widespread extreme (D3) to exceptional (D4) drought continues across much of the Southwest. Another week of warm, dry weather didn’t help. High temperatures ranged from 4 degrees above normal in the Northwest to 15 degrees above normal in the Southwest while little to no precipitation fell across much of the region. Where exceptions occurred, in the Pacific Northwest and the Northern Rockies, totals generally weren’t enough to overcome shortages. In eastern Washington, abnormal dryness (D0) and moderate drought (D1) expanded as precipitation deficits continued to increase, drying out soils. Conditions also deteriorated in Oregon.
Most notably, D3 expanded and D4 was introduced in south central Oregon in response to record low water-year-to-date total precipitation, streamflow and soil moisture. It’s worth noting that since the U.S. Drought Monitor began in 2000, this is only the second time that D4 has occurred in the state (last occurrence in summer and fall of 2003). In California, the April 1 snow survey showed that snow water content in the Sierra Nevada Mountains was at 59% of average and the state, as a whole, received about 50% of its average precipitation for the water year. Two consecutive dry years have left reservoirs about half full. These precipitation deficits, combined with high temperatures, have reduced streamflow, dried out soils, and stressed vegetation.
Changes to this week’s map include an expansion of D3 in northern California and western Nevada and an expansion of D2 (severe drought) and D3 in southern California. D1 expanded in northwest Wyoming and southeast Montana to reflect below normal precipitation over the water year and its effect on soil moisture and streamflow. Eastern Montana also saw deteriorating conditions with an expansion of D2 and D3. Here, the lack of precipitation over the last 2 to 3 months has dried out soils and stressed vegetation. USDA reports that, as of April 4, 76% of the state’s topsoil was rated short to very short indicating that soil moisture supplies are significantly less than what is required for normal crop growth development....
....MUCH MORE
