An atmospheric river led to heavy rain and high-elevation snow across the West with the largest amounts throughout California on Dec. 30 and 31. Preceding this AR, enhanced onshore flow also resulted in widespread rain and high-elevation snow from the West Coast eastward to the Continental Divide.
A winter storm affected southern South Dakota and western to central Nebraska where 6 to 18 inches of snowfall occurred on Jan. 2. Mostly dry weather prevailed along most of the East Coast and southern Great Plains. Following the Arctic air outbreak during late December, a rapid warming trend began during the final days of 2022. Five-day temperatures (Dec. 27, 2022, to Jan. 2, 2023) averaged more than 10 degrees F above normal across the central and eastern U.S.
South
Widespread heavy rainfall (2 to 6 inches) resulted in a broad 1-category improvement to the lower Mississippi Valley and eastern Texas, which makes much of these areas drought-free. Degradations made to central and southern Texas were based on SPI at various time scales and 28-day streamflow. Following a dry week, much of Oklahoma and northwestern Texas remain designated with severe (D2) to exceptional (D4) drought.
Midwest
Widespread precipitation (1 to 3 inches) this past week led to a broad 1-category improvement across the middle Mississippi and Ohio River Valley. This recent heavier precipitation nearly eliminated 60-day precipitation deficits throughout Kentucky along with much of Illinois and Missouri. Ninety-day precipitation deficits are largest (more than 4 inches) across parts of Indiana and Ohio where broader moderate (D1) drought continues. Despite an increase in precipitation across Iowa during December, longer-term indicators continue to support D1+ drought. Since southern Minnesota received heavier precipitation after 7am ET Jan. 3, this region will be evaluated for potential changes next week.
High Plains
Based on heavy precipitation (1 to 3 inches, liquid equivalent) this past week along with above-normal snowpack, a 1-category improvement was made to western Colorado. Beneficial precipitation also prompted improving drought conditions across north-central and northeastern Colorado. A decrease in the spatial coverage of extreme (D3) drought was made to central Nebraska. Twelve-month SPI and the long-term blend support the continued widespread severe (D2) to exceptional (D4) drought coverage for the central Plains. Norfolk, Nebraska, with a period of record dating back to 1888, had its driest year on record in 2022.
