Causes for Multiyear Droughts in the Missouri River Basin

The history of drought in the Missouri River Basin indicates a preference for short-lived
seasonal-to-annual events, suggesting that factors conducive for multiyear droughts are rare.
However, it is the few long-lived droughts of the 1930s and 1950s that have become cultural
folklore on the Great Plains. These droughts have left a permanent imprint on the region’s
sense of vulnerability because each caused widespread loss in livelihoods and induced mass
human migration. As disruptive as short-lived droughts can be, it is ultimately the much deeper
scars inflicted by multiyear droughts that make them of greatest concern.

In response to the Type 1 FY2020 Modeling, Analysis, Predictions and Projections (MAPP)
Program solicitation, Characterizing and Anticipating U.S. Droughts’ Complex Interactions
(NOAA-OAR-CPO-2020-2006076, 2808167), we propose to analyze physical factors responsible
for prolonged drought in the Missouri River Basin and thereby adduce techniques that can
better inform risk assessments for a first-year drought evolving into a sustained multiyear event
of at least two-years duration. Titled, Causes for Multiyear Droughts in the Missouri River Basin,
the project will utilize a hierarchy of earth system model simulations and a tree ring-based
drought atlas to achieve the following objectives: (A) Characterize droughts of two years or
longer duration, with comparison of model statistics to a tree ring-based drought atlas; (B)
Quantify how, and by how much, sea surface temperature (SST) variability conditions the
probability of sustained drought; (C) Determine to what extent land surface dryness developed
in a first-year drought alters the likelihood for drought in the subsequent year.

The proposed work will clarify whether the monitored states of the ocean and land surface can
offer early warning for the likelihood of first-year droughts becoming multiyear events in
Missouri River Basin, thereby furthering our predictive understanding of the region’s
hydroclimate. An improved predictive understanding can be applied to operational products
like NOAA’s Drought Outlooks, to drought early warning practices in the National Integrated
Drought Information System’s (NIDIS) Missouri River Basin Drought Early Warning System and
to educate and engage the rich network of NIDIS partners, including tribal, federal, state and
local entities.

The proposed work addresses all three priority areas of the MAPP solicitation as follows: (A)
Explain why extreme and prolonged droughts may occur and describe their characteristics
relative to one-year droughts; (B) Examine the predictability of droughts and whether precursor
mechanisms like SST and land surface states condition the likelihood that a first-year drought
becomes a multi-year drought; (C) Inform applications such as new/improved modeling and/or
methodologies for prediction/projection that can advise drought early warning in the NIDIS
Missouri River Basin Drought Early Warning System. The proposed work also addresses the
mission of NOAA and its programs. NOAA’s mission of science, service and stewardship, “to
understand and predict changes in climate and to share [that] knowledge and information with
others” is addressed. Climate Program Office’s long-term climate goals, such as its, “focus on
climate intelligence and climate resilience, in support of NOAA’s goals” is addressed.

Climate Risk Area: Water Resources