West Drought Summary
Beneficial precipitation, with locally heavy high-elevation snow, continued across the Four Corners region into the first week of the New Year. Based on recent precipitation, near to above-average precipitation during the past 6 months, and SPI values near normal, abnormal dryness was removed from southeast Arizona with a slight reduction in the coverage of D1 and D2 where recent amounts were heaviest. Small areas of improvement also were made across southwest Colorado. Cortez in Montezuma County has received about an inch above normal precipitation since the beginning of the water year, supporting an upgrade from D4 to D3. In the San Luis Valley, recent precipitation prompted an improvement from D3 to D2. These areas of improvement are limited to the lower elevations since snowpack remains slightly below normal at the higher elevations. During the past week, local precipitation amounts exceeded 1 inch (liquid equivalent) in Unitah County, Utah where D3 was improved to D2. Farther to the north and east, little to no precipitation and above-average temperatures resulted in an increase in D1 across Adams and El Paso counties of north-central Colorado and an expansion of D0 from north-central Colorado into southern Wyoming. Abnormal dryness (DO) was removed from north-central Montana in early December. However, it has remained dry since that time and D0 may need to be reintroduced in the coming weeks.
Onshore flow continued to bring widespread rain and high-elevation snow to the West Coast during the first week of the New Year. However, ACIS indicates that precipitation has averaged below normal during the past 30 days across a majority of the Pacific Northwest and California. Santa Barbara and Ventura counties received another round of heavy precipitation (locally more than 2 inches) this past week, producing mud slides in burn-scarred hillsides. An increase in water storage on Cachuma Reservoir was noted. Based on recent precipitation and 12 to 24-month SPIs, a decrease in the coverage of D3 was made to these counties in southern California. According to SNOTEL, basin snow water content (SWE) remains below 75 percent of normal across the southern Cascades where D2 to D3 is designated. Recent heavy precipitation and only small precipitation deficits at 60 days prompted removal of abnormal dryness across parts of western Washington.
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