The latest U.S. Drought Monitor week, posted Nov. 27, indicated improvement in drought-related conditions across areas of the West, Lower Midwest, Northeast, and the South.

On the map, widespread improvements were made in drought-affected areas across Arizona as well as in other areas of the Desert Southwest including western New Mexico and southern Utah. In California, storms during the past few weeks, in addition to an overall wetter pattern in recent months, have continued to help improve conditions leading to removal of areas of drought in Southern California.

Since Oct. 1, numerous locations in California, southern Nevada, and Arizona have received record to near-record precipitation accumulations including Santa Barbara, California (+8.2-inch departure from normal), Ontario, California (+4.11 inches), Las Vegas, Nevada (+2.08 inches), and Flagstaff, Arizona (+5.71 inches). In the Pacific Northwest, drier-than-normal conditions have prevailed (past 30-days) across areas of the region including central and eastern Oregon, southern Idaho, and southwestern Montana.

Moreover, snowpack conditions across the Pacific Northwest continued to lag behind normal levels. In the Lower Midwest (Missouri) and areas of the South (Texas), widespread improvements were made in response to rainfall events during the past week. In areas of the Upper Midwest (Michigan and Wisconsin), exceptionally dry conditions have prevailed during the past 60-day period with numerous locations observing record to near-record dryness.

In terms of reservoir storage in areas of the West, California’s reservoirs continue to be at or above historical averages for the date (Nov. 24), with the state’s two largest reservoirs (Lake Shasta and Lake Oroville) at 110% and 100% of their averages, respectively. In the Southwest, Lake Powell is currently 29% full and Lake Mead is 32% full, with the total Colorado River system contents at 37% of capacity on Nov. 23 (compared to 42% of capacity at the same time last year), according to the U.S. Bureau of Reclamation.

In Arizona, the Salt River Project is reporting that the Salt River system reservoirs are 54% full, the Verde River system is 68% full, and the total reservoir system is 56% full (compared to 73% full a year ago). New Mexico’s largest reservoir, Elephant Butte, along the Rio Grande River is currently 5% full (12% of average). Washington’s Franklin D. Roosevelt Lake is 94% full (105% of average for the date), Idaho’s American Falls Reservoir on the Snake River is 25% full (64% of average), and Hungry Horse Reservoir in northwestern Montana is 88% full (107% of average).

The U.S. Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the U.S. Department of Agriculture and the National Oceanic Atmospheric Administration. (Map courtesy of NDMC.)

South

Across much of the region, generally dry conditions prevailed, especially in the far southern and western portions of the region, with little or no precipitation observed.

In contrast, light to moderate rainfall (2 to 4+ inches) was observed along a swath extending from central Texas to southwestern Arkansas. The beneficial rainfall led to one-category improvements in areas of Moderate (D1) to Extreme Drought (D3) with most of the improvements focused on areas of central and northeastern Texas. Elsewhere, minor improvements were made on the map in southeastern Oklahoma and southwestern Arkansas.

Average temperatures were well above normal across the region with anomalies ranging from 4 to 16 degrees Fahrenheit above normal. Looking at reservoir conditions in Texas, Water for Texas (Nov. 25) was reporting statewide reservoirs at 74% full, with many reservoirs in the eastern part of the state in very good condition, while numerous reservoirs in the western portion of the state were experiencing continued below-normal levels.

Midwest

Improvements were made in the southern extent of the region in Missouri in response to widespread rainfall (1 to 2.5 inches) across the state.

Average temperatures were above normal across the western and southern extent of the region, with anomalies ranging from 5 to 15 degrees above normal and the greatest departures observed in western Minnesota and southern Missouri.

Temperatures were cooler in the eastern half of the region ranging from 5 degrees above normal to 5 degrees below normal (central and northern Michigan, eastern Ohio). Using the Southeast Regional Climate Center’s Climate Perspectives tool, the past two months have been very dry across much of the region, with record to near-record dryness observed in the several locations: Duluth, Minnesota, (-4.52 inch departure); and St. Louis, Missouri, (-4.3 inches).

High Plains

Minor changes were made in the region, including changes in eastern Kansas, Nebraska, and southwestern South Dakota.

Precipitation across the region was generally light and primarily restricted to eastern and central portions of Kansas as well as in eastern and central South Dakota. In terms of average temperatures, warmer-than-normal temperatures (5 to 15+ degrees above normal) were observed across the region with the greatest anomalies observed in the Dakotas.

West

Out west, recent storms have delivered much-needed precipitation to drought-affected areas of southern Colorado and western New Mexico. Widespread improvements were made in isolated areas of Colorado and New Mexico.

Moreover, the recent storm activity in the southern extent of the region has boosted snowpack conditions in the Nacimiento Mountains (northern New Mexico). Elsewhere, snowpack conditions were poor across most of the Intermountain West and Pacific Northwest. In other parts of the region, some minor degradations were made on the map in northern Colorado and north-central Montana.

Looking ahead

The National Weather Service’s Weather Prediction Center 7-Day Quantitative Precipitation Forecast calls for moderate precipitation accumulations ranging from 2 to 4+ inches (liquid) across areas of the South and areas of the Southeast. Likewise, a significant winter storm is expected to impact the Upper Midwest and Great Lakes regions.

In the West, dry conditions are expected to prevail across California and the Great Basin, while some lighter accumulations are expected across the Intermountain West. In the Pacific Northwest, moderate accumulations are expected across western Washington and some lesser accumulations across areas of the Northern Rockies of Idaho and northwestern Montana. The Climate Prediction Center 6-to-10-day Outlook calls for a moderate-to-high probability of below-normal temperatures across the eastern half of the West, Plains, South, Midwest, and Northeast.

In terms of precipitation, there is a low-to-moderate probability of above-normal precipitation across most of the conterminous U.S. except for northern California and western Oregon where below-normal precipitation is favored.

David Simeral is with the Western Regional Climate Center.