This Week’s Drought Summary
A couple Pacific weather systems moved across the contiguous U.S. (CONUS) during this U.S. Drought Monitor (USDM) 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 (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) 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.
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.