A couple Pacific weather systems moved across the contiguous U.S. during this U.S. Drought Monitor week. The storm track kept to the northern states, but the systems dragged cold fronts with them that stretched the width of the CONUS, from the Great Lakes to the Gulf of Mexico coast.
The systems spread rain and snow to the coastal Pacific Northwest and parts of the northern Rockies, but they weakened as they moved through a western ridge. This circulation pattern starved them of moisture, so much of the West to Great Plains received little to no precipitation, but the fronts picked up Gulf of Mexico moisture as they moved east, spreading precipitation across the Lower Mississippi to Ohio Valleys, eastern Great Lakes, and Northeast.
Only a few areas received above-normal precipitation for this time of year, including spots in the Pacific Northwest, Ohio Valley, Deep South Texas, and the southern half of Florida. Weekly temperatures averaged near to cooler than normal in the Pacific Northwest, Great Lakes, Ohio Valley, and Mid-Atlantic states. Much of the West, Great Plains, and Southeast were warmer than normal.
Persistent above-normal temperatures in the Plains contributed to excessive evapotranspiration in western portions of the Great Plains as well as parts of the West, as seen in EDDI and ESI indicators. Lack of precipitation, excessive evapotranspiration, and windy conditions further dried soils, again especially in western portions of the Plains, as seen in several soil moisture indicators. Drought indicators such as the Standardized Precipitation Index and Standardized Precipitation Evapotranspiration Index showed dry conditions at long-term time scales in the West to northern Plains, at short-term time scales in the Southeast to Mid-Atlantic and Lower Mississippi Valley regions, and both short- and long-term time scales from the Southwest to southern and central Plains. Precipitation over the last 4 weeks lessened drought intensity slightly in parts of the West, but continued dryness expanded or intensified drought in parts of the Plains, Deep South, Southeast, and Mid-Atlantic states.
South
Half an inch to locally an inch of rain fell over Mississippi, Tennessee, eastern parts of Arkansas, and parts of Louisiana. Half an inch to locally over 2 inches was observed over Deep South Texas. Other than those areas, most of the South received no precipitation this week. Drying soils, high evapotranspiration, and worsening SPI and SPEI drought indicators prompted expansion of D0-D3 in western parts of Oklahoma and Texas, while D0-D1 expanded in eastern portions of Texas and Oklahoma to western parts of Mississippi. The rains in Deep South Texas eliminated moderate drought and contracted abnormal dryness along the southern Rio Grande River.
Midwest
Half an inch to locally 1.5 inches of precipitation occurred across the Ohio Valley, with the heaviest amounts in Kentucky. Eastern portions of the Great Lakes received half an inch of precipitation. But western portions of the region were dry, with little to no precipitation falling. Abnormal dryness expanded in western Illinois near St. Louis; otherwise, no change in drought status occurred in the Midwest.
High Plains
Except for half an inch or more of precipitation over the mountains of northern Colorado and northwest Wyoming, a tenth of an inch to no precipitation was observed across the High Plains region. Drying soils, high evapotranspiration, and worsening SPI and SPEI drought indicators led to expansion of D3 in northeast and southeast Colorado and southwest Kansas, and D0-D2 in eastern portions of Colorado and western portions of Kansas. Decreasing soil moisture, lack of snow, and dry long-term SPI/SPEI indicators prompted expansion of D3 in north central Wyoming and D1 and D2 in southeast Wyoming.
West
Half an inch to locally 2 inches of precipitation fell along coastal areas of Oregon and Washington, with half an inch over eastern Washington to northern Idaho. Less than half an inch occurred further south to northern portions of California and the Great Basin. Areas further south received no precipitation this week. Dry soils, high evapotranspiration, and severely dry SPI and SPEI values prompted expansion of D4 in northern Montana.
