Drought news: Temperatures were well above average this past week across the West #drought

Click on a thumbnail graphic to view a gallery of drought data from the US Drought Monitor. Here’s an excerpt:

Summary

This U.S. Drought Monitor week saw improvements along the West Coast as a series of strong Pacific storms produced substantial rainfall accumulations in northern California and western portions of Oregon and Washington. The storms were the first significant precipitation event to affect California since mid-December. Since the moisture associated with these storms was subtropical in origin, the vast majority of the precipitation fell as rain while snowfall was restricted to the higher elevations. Overall, the storms had little impact on the well-below-normal snowpack conditions across the Sierra Nevada and Cascades ranges. Elsewhere in the West, mountain snowpack conditions are currently below normal across the Great Basin and Southwest as well as in parts of the Intermountain West and Central Rockies. Reservoir storage remains below normal in Arizona, California, Nevada, New Mexico, Oregon, and Utah in contrast to slightly above average conditions in Colorado, Idaho, Montana, Washington, and Wyoming. Temperatures during the past week were well above normal in the western half of the conterminous U.S. with record high temperatures observed across the West and Central Plains. In contrast, the Northeast remained in a cold, snowy pattern with areas of Massachusetts, New York, New Hampshire, and Vermont receiving more than a foot of new snowfall…

The Plains

Across the northern and southern Plains states, temperatures were well above normal for the period. During the weekend, record high temperatures were observed in Kansas and South Dakota. In western Kansas, temperatures soared into the high 70s and low 80s, while portions of South Dakota reached the mid-60s. On this week’s map, changes included expansion of Abnormally Dry (D0) into western South Dakota in response to above normal temperatures and precipitation deficits during the past 30 days. In southeastern Kansas, some minor expansion in an area of Moderate Drought (D1) occurred in response to warmer temperatures and deterioration in local stock pond levels…

The West

During the past week, a series of strong Pacific storms came ashore late last week and continued throughout the weekend. This storm system – which tapped a conveyor-belt of warm, moist air from the subtropics – delivered widespread, heavy rainfall to northern California and the western portions of Oregon and Washington. In northern California, liquid precipitation accumulations ranged from three-to-fifteen inches, with the highest accumulations centered over the mountains of northwestern and north-central California as well as further south in the Santa Cruz and Santa Lucia ranges. In the northern half of the Sierra Nevada Range, rainfall accumulations ranged from three-to-ten inches, and the greatest accumulations occurred on the western slope between 2000 and 7000 feet in elevation. Snow levels were generally high (above 8000 feet) throughout the storms, and the cumulative effect of the snowfall received did not have a significant impact on the poor snowpack conditions across the range. According to the California Department of Water Resources, California’s snowpack (snow water equivalent) is currently at 27% of normal. On a more positive note, runoff associated with the event provided the addition of approximately 500,000 acre feet of inflow to the four major reservoirs (Folsom, Oroville, Shasta, and Trinity) in northern California. In response to the storm, a one-category improvement was made to areas of Extreme Drought (D3) in northwestern California as well as in the Santa Cruz Mountains (between San Francisco and Santa Cruz) and in the northern half of the Santa Lucia Range along the Central Coast. No changes were made on the map in the Sierra Nevada Range because snowpack conditions remain well below normal. In the Pacific Northwest, the same series of storms brought heavy rains (four-to-eight inches) to western portions of Oregon and Washington leading to one-category improvements in southwestern Oregon. According to the National Resource Conservation Service (NRCS) SNOTEL network, the snowpack in the Cascades of Oregon and Washington remains well below normal for this time year with snow water equivalent (SWE) percentages ranging from 7 to 64% of normal with the lowest values being observed in Oregon. Overall, the past week was unseasonably warm (three to fifteen degrees above normal) across the entire West with record high temperatures observed in California, Colorado, Idaho, Nevada, Utah, Washington, and Wyoming…

Looking Ahead

The NWS HPC 7-Day Quantitative Precipitation Forecast (QPF) calls for light precipitation accumulations (generally less than one inch) across the eastern half of the country while portions of the central and southern Rockies are forecasted to receive between one and two inches of liquid accumulation. The 6–10 day outlooks call for a high probability of above-normal temperatures across the West while below-normal temperatures are forecasted for the eastern half of the country. A high probability of above-normal precipitation is forecasted across eastern portions of the West, Plains, South, Southeast, and the Mid-Atlantic regions while below-normal precipitation is expected in the Pacific Northwest, northern California, Great Basin, and the Upper Midwest.

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