Courtesy: State Climatology Office
This post will be updated monthly until drought conditions improve dramatically.
For the second year in a row, significant drought conditions developed in Minnesota during 2022, this time in response to quick-hitting and steep precipitation deficits. Unlike the previous year's drought, which hit northern Minnesota the hardest and peaked during late summer, this one originated in southern Minnesota and escalated during the fall. As of early November 2022, the 2021 drought was the larger and "worse" of the two episodes in all categories, though the 2022 drought was still underway and likely to extend into 2023.
Another major difference was speed of drought onset. The 2021 drought had built slowly since at least mid-2020, and possibly since late in the 2019-20 winter. When June through August 2021 became northern Minnesota's warmest and fourth-driest on record, it only accelerated and worsened a regional drying process that was already well underway.
By contrast, the episode in 2022 qualified as a "flash drought," defined by NOAA and the National Integrated Drought Information System as the rapid onset of drought conditions. Late winter and spring had been very wet, with February through May of 2022 ranking 8th wettest on record, and over 40% wetter than 20th century averages. These wet conditions were especially pronounced in northern Minnesota, which saw significant and historic flooding in the same areas that had seen the highest levels of drought just eight months earlier.
In southern Minnesota, the rains stopped abruptly during May of 2022, and June and July both had just a quarter to a third of normal precipitation in many areas. August had near-normal precipitation and was even wet in some areas, but September became the driest on record in the Twin Cities, and October finished sixth driest. The period from June through October ended 11.52 inches short for the Twin Cities, marking the area's largest five-month deficit on record, when comparing historical precipitation to what would have been "normal" for the time.
The precipitation shortfalls were impressive, but two factors limited the severity of the drought categories during summer and fall: first, the wet spring had provided some "cushioning" against massive water losses, slowing down the onset of dire conditions. Second, the summer was warm but not nearly as warm or hot as 2021. Extremes of heat can speed speed up water loss and intensify moisture stress. Fortunately, this summer's heat was less severe than what Minnesota has experienced historically during dry summers, and did not play a major role in worsening this episode.
Updated Nov 8, 2022