Summary

March 2, 2018 - This past week was marked by heavy rain across the mid-South and lower Midwest. The excessive rain broke daily precipitation records, caused flooding in many locations, and led to significant improvements to drought. The upper Midwest received significant snowfall as colder than normal temperatures dominated the area. Precipitation also fell in other parts of the country including the northern Plains, Northeast, and much of the West. Dry weather was confined to southern California, the Desert Southwest, and lower Southeast. A stark temperature contrast existed between the western and eastern halves of the country. While the West saw record-breaking cold, the East saw record-breaking warmth. Temperatures in the West were typically between 8 and 12 degrees below normal, though the northern Rockies and High Plains saw departures of more than 20 degrees below normal. In the eastern half of the country, departures ranged from 2 to more than 20 degrees above normal.

Northeast

During the past week, widespread areas of 0.5 to 2-3 inches of precipitation fell over much of the Northeast, with the heaviest amounts falling in western Pennsylvania and West Virginia. The rainfall in Pennsylvania helped to erase the lingering abnormal dryness in the eastern half of the state. Although Maryland has received rainfall, depictions of drought and abnormal dryness remain as groundwater levels have yet to recharge.

Southeast

This week in the Southeast, the heavy rain swath in the central United States brought moderate to heavy rain amounts to parts of Georgia, Alabama, Tennessee, and Virginia, with parts of western Tennessee receiving over 5 inches of rain. The rains in Alabama reduced short-term precipitation deficits and helped streamflow recover, resulting in one-category improvements for parts of northern and central Alabama. In central Georgia, moderate drought expanded as short-term rainfall deficits continued to build and warmer than normal temperatures helped to dry out soil. Warm, dry conditions continued across the Florida Peninsula, where abnormal dryness persisted and expanded in the central and southern Florida Peninsula, respectively.

West

An upper-level trough persisted in the West this week, bringing cool temperatures to all areas and moderate to heavy precipitation to parts of Idaho, western Oregon and Washington, the San Juan and Snowy Ranges in Colorado and Wyoming, and the Sierra Nevada. Abnormal dryness developed in northeastern lower Idaho as seasonal precipitation deficits intensified. Severe drought was introduced southeast Utah as water year precipitation and snow water equivalent are ranked in the lowest percentiles. Urban areas of southern California already in severe drought have continued to experience largely dry conditions; conditions remain at status quo because of the recent rain and lack of widespread water supply issues.

High Plains

Some light to moderate precipitation fell in central and eastern Nebraska and the eastern Dakotas, while heavier precipitation fell in southeast Kansas during the series of major rain/snow events in the central and southern United States. Abnormally dry conditions improved in parts of eastern Nebraska, north-central Nebraska, southeast South Dakota, northeast Colorado, and southwest Nebraska. A small part of the moderate drought in central South Dakota improved to abnormal dryness. Despite ample snowfall amounts in South Dakota in the last week, water content was low and did not provide much relief in the moderate to severe drought conditions. The area of severe drought in the western Dakotas was changed to long-term drought (indicated by the change from “SL” to “L” on the map) as the impacts are limited to lingering groundwater and long-term precipitation deficits.