La Niña gives way to dry spring

Although weakening has begun for La Niña, a phenomenon marked by cool equatorial waters over the central and eastern Pacific Ocean, influence over North American weather patterns should continue well into spring. For example, La Niña-driven storm tracks are expected to remain active across the Pacific Northwest and the Lower Midwest, respectively, leading to above-normal spring precipitation in those regions. In contrast, much of the nation’s southwestern quadrant, an area that extends across the central and southern Great Plains, should experience drier-than-normal spring weather. With drought already in place across large sections of the Great Plains and Southwest, La Niña’s “parting gift” of a dry spring could result in additional stress on rangeland, pastures and winter wheat, as well as ongoing water supply issues in areas dependent on snowpack or reservoir storage.

Following a very wet December across much of the western United States, a drier pattern has taken hold in early 2022. Western spring runoff expectations, initially favorable as the new year began, have faded amid the protracted spell of mild, dry weather. Heading toward spring, storage in California’s 154 primary intrastate reservoirs stood at just over 17 million acre-feet, lower than a year ago and roughly three-quarters of average for this time of year. Similar storage issues exist in many other parts of the West, extending from Oregon and California to the central and southern Rockies.

National drought coverage remains at historically high levels. In fact, drought coverage in the lower 48 states has continuously exceeded 40% since September 2020, according to the U.S. Drought Monitor. Additionally, U.S. drought coverage has been above 50% since late November 2021, marking the longest such streak since June 2012-April 2013. As mentioned earlier, one manifestation of drought has been adverse impacts on winter wheat; according to a mid-winter report from the U.S. Department of Agriculture, at least one-quarter of the wheat was rated in very poor to poor condition in several states, including Texas (71%), Montana (65%), Oklahoma (43%), Colorado (40%) and Kansas (31%).